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1. Inclusive e$^+$e$^-$ production in collisions of pions with protons and nuclei in the second resonance region of baryons

Author: Yassine, R. Abou, Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Becker, M., Behnke, C., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Chlad, L., Chudoba, P., Ciepał, I., Deb, S., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Förtsch, J., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Hojeij, F., Holzmann, R., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Lapidus, K., Linev, S., Linz, F., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Molenda, A., Müntz, C., Münzer, R., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parpottas, Y., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Povar, T., Prościnki, P., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Scheib, T., Schild, N., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Spataro, S., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Vazquez-Doce, O., Wagner, V., Weber, A. A., Wendisch, C., Wiebusch, M. G., Wirth, J., Wladyszewska, A, Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: Inclusive e$^+$e$^-$ production has been studied with HADES in $\pi^-$ + p, $\pi^-$ + C and $\pi^- + \mathrm{CH}_2$ reactions, using the GSI pion beam at $\sqrt{s_{\pi p}}$ = 1.49 GeV. Invariant mass and transverse momentum distributions have been measured and reveal contributions from Dalitz decays of $\pi^0$, $\eta$ mesons and baryon resonances. The transverse momentum distributions are very sensitive to the underlying kinematics of the various processes. The baryon contribution exhibits a deviation up to a factor seven from the QED reference expected for the dielectron decay of a hypothetical point-like baryon with the production cross section constrained from the inverse $\gamma$ n$\rightarrow \pi^-$ p reaction. The enhancement is attributed to a strong four-momentum squared dependence of the time-like electromagnetic transition form factors as suggested by Vector Meson Dominance (VMD). Two versions of the VMD, that differ in the photon-baryon coupling, have been applied in simulations and compared to data. VMD1 (or two-component VMD) assumes a coupling via the $\rho$ meson and a direct coupling of the photon, while in VMD2 (or strict VMD) the coupling is only mediated via the $\rho$ meson. The VMD2 model, frequently used in transport calculations for dilepton decays, is found to overestimate the measured dielectron yields, while a good description of the data can be obtained with the VMD1 model assuming no phase difference between the two amplitudes. Similar descriptions have also been obtained using a time-like baryon transition form factor model where the pion cloud plays the major role., Comment: (HADES collaboration)
Published: 2023

2. Investigation of the $\mathbf{\Sigma^{0}}$ Production Mechanism in p(3.5 GeV)+p Collisions

Author: Yassine, R. Abou, Arnold, O., Becker, M., Bergmann, P., Blanco, A., Blum, C., Böhmer, M., Carolino, N., Chlad, L., Chudoba, P., Ciepał, I., Dreyer, J., Esmail, W., Fabbietti, L., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Grunwald, M., Gumberidze, M., Harabasz, S., Höhne, C., Hojeij, F., Holzmann, R., Huck, H., Idzik, M., Kämpfer, B., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Linz, F., Lopes, L., Lorenz, M., Malige, A., Markert, J., Metag, V., Michel, J., Molenda, A., Müntz, C., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parpottas, Y., Parschau, M., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Prozorov, A., Przygoda, W., Ramstein, B., Rathod, N., Ritman, J., Rost, A., Rustamov, A., Salabura, P., Schild, N., Schwab, E., Seck, F., Singh, U., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Wagner, V., Weber, A. A., Wendisch, C., Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: The production of $\Sigma^0$ hyperons in proton proton collisions at a beam kinetic energy of 3.5 GeV impinging on a liquid hydrogen target was investigated using data collected with the HADES setup. The total production cross section is found to be $\mathrm{\sigma (pK^{+}\Sigma^{0}) [\mu b] = 17.7 \pm 1.7 (stat) \pm 1.6 (syst)}$. Differential cross section distributions of the exclusive channel $\mathrm{pp \rightarrow pK^{+}\Sigma^{0}}$ were analyzed in the center-of-mass, Gottfried-Jackson and helicity reference frames for the first time at the excess energy of 556 MeV. The data support the interplay between pion and kaon exchange mechanisms and clearly demonstrate the contribution of interfering nucleon resonances decaying to $\mathrm{K^{+}\Sigma^{0}}$. The Bonn-Gatchina partial wave analysis was employed to analyse the data. Due to the limited statistics, it was not possible to obtain an unambiguous determination of the relative contribution of intermediate nucleon resonances to the final state. However nucleon resonances with masses around 1.710 $\mathrm{GeV/c^{2}}$ ($\mathrm{N^{*}(1710)}$) and 1.900 $\mathrm{GeV/c^{2}}$ ($\mathrm{N^{*}(1900)}$ or $\mathrm{\Delta^{*}(1900)}$) are preferred by the fit.
Published: 2023

3. Production of hydrogen isotopes and charged pions in p (3.5 GeV) + Nb reactions

Author: Yassine, R. Abou, Arnold, O., Becker, M., Bergmann, P., Blanco, A., Blume, C., Böhmer, M., Carolino, N., Chlad, L., Chudoba, P., Ciepał, I., Dreyer, J., Esmail, W. A., Fabbietti, L., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Grunwald, M., Gumberidze, M., Harabasz, S., Höhne, C., Hojeij, F., Holzmann, R., Huck, H., Idzik, M., Kämpfer, B., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Lopes, L., Lorenz, M., Malige, A., Markert, J., Metag, V., Michel, J., Molenda, A., Müntz, C., Naumann, L., Nowakowski, K., Otto, J. -H., Parpottas, Y., Parschau, M., Pechenov, V., Pechenova, O., Pietraszko, J., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Rost, A., Rustamov, A., Salabura, P., Schild, N., Schwab, E., Seck, F., Singh, U., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Wagner, V., Weber, A. A., Wendisch, C., Zbroszczyk, H. P., Zherebtsova, E., Zumbruch, P., Kamys, B., and Sharma, S.
Subjects: Nuclear Experiment
Abstract: The double differential production cross sections, $d^2\sigma/d\Omega dE$, for hydrogen isotopes and charged pions in the reaction of p + Nb at 3.5 GeV proton beam energy have been measured by the High Acceptance DiElectron Spectrometer (HADES). Thanks to the high acceptance of HADES at forward emission angles and usage of its magnetic field, the measured energy range of hydrogen isotopes could be significantly extended in comparison to the relatively scarce experimental data available in the literature. The data provide information about the development of the intranuclear cascade in the proton-nucleus collisions. They can as well be utilized to study the rate of energy/momentum dissipation in the nuclear systems and the mechanism of elementary and composite particle production in excited nuclear matter at normal density. Data of this type are important also for technological and medical applications. Our results are compared to models developed to describe the processes relevant to nuclear spallation (INCL++) or oriented to probe either the elementary hadronic processes in nuclear matter or the behavior of compressed nuclear matter (GiBUU).
Published: 2023

4. Hadron Production and Propagation in Pion-Induced Reactions on Nuclei

Author: Yassine, R. Abou, Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Becker, M., Behnke, C., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Chlad, L., Chudoba, P., Ciepał, I., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Förtsc, J., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Hojeij, F., Holzmann, R., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Lapidus, K., Linev, S., Linz, F., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Molenda, A., Müntz, C., Münzer, R., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parpottas, Y., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Povar, T., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Scheib, T., Schild, N., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Spataro, S., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Vazquez-Doce, O., Wagner, V., Weber, A. A., Wendisch, C., Wiebusch, M. G., Wirth, J., Zbroszczyk, H. P., Zherebtsova, E., Zumbruch, P., Curceanu, C., Piscicchia, K., and Scordo, A.
Subjects: Nuclear Experiment
Abstract: Hadron production ($\pi^\pm$, proton, $\Lambda$, $K_S^0$, $K^\pm$) in $\pi^- + \mathrm{C}$ and $\pi^- + \mathrm{W}$ collisions is investigated at an incident pion beam momentum of $1.7~\mathrm{GeV}/c$. This comprehensive set of data measured with HADES at SIS18/GSI significantly extends the existing world data on hadron production in pion induced reactions and provides a new reference for models that are commonly used for the interpretation of heavy-ion collisions. The measured inclusive differential production cross-sections are compared with state-of-the-art transport model (GiBUU, SMASH) calculations. The (semi-) exclusive channel $\pi^- + A \rightarrow \Lambda + K_S^0 +X$, in which the kinematics of the strange hadrons are correlated, is also investigated and compared to a model calculation. Agreement and remaining tensions between data and the current version of the considered transport models are discussed.
Published: 2023

5. Proton, deuteron and triton flow measurements in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV

Author: HADES collaboration, Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chlad, L., Ciepal, I., Deveaux, C., Dreyer, J., Epple, E., Fabbietti, L., Filip, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Greifenhagen, R., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Kämpfer, B., Kardan, B., Koenig, I., Koenig, W., Kohls, M., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kugler, A., Kunz, T., Lalik, R., Lapidus, K., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K., Parpottas, Y., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Przygoda, W., Pysz, K., Ramos, S., Ramstein, B., Rathod, N., Rodriguez-Ramos, P., Rosier, P., Rost, A., Rustamov, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Sobolev, Yu. G., Spataro, S., Spies, S., Ströbele, H., Stroth, J., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Wójcik, D., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: High precision measurements of flow coefficients $v_{n}$ ($n = 1 - 4$) for protons, deuterons and tritons relative to the first-order spectator plane have been performed in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV with the High-Acceptance Di-Electron Spectrometer (HADES) at the SIS18/GSI. Flow coefficients are studied as a function of transverse momentum $p_{t}$ and rapidity $y_{cm}$ over a large region of phase space and for several classes of collision centrality. A clear mass hierarchy is found for the slope of $v_{1}$, $d v_{1}/d y^{\prime}|_{y^{\prime} = 0}$ where $y^{\prime}$ is the scaled rapidity, and for $v_{2}$ at mid-rapidity. Scaling with the number of nucleons is observed for the $p_{t}$ dependence of $v_{2}$ and $v_{4}$ at mid-rapidity, which is indicative for nuclear coalescence as the main process responsible for light nuclei formation. $v_{2}$ is found to scale with the initial eccentricity $\langle \epsilon_{2} \rangle$, while $v_{4}$ scales with $\langle \epsilon_{2} \rangle^{2}$ and $\langle \epsilon_{4} \rangle$. The multi-differential high-precision data on $v_{1}$, $v_{2}$, $v_{3}$, and $v_{4}$ provides important constraints on the equation-of-state of compressed baryonic matter., Comment: 21 pages, 18 figures, 4 tables; Figs. 11 updated; The manuscript has associated data in the HEPData repository: https://doi.org/10.17182/hepdata.152804
Published: 2022
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6. Measurement of global polarization of {\Lambda} hyperons in few-GeV heavy-ion collisions

Author: Yassine, R. Abou, Adamczewski-Musch, J., Asal, C., Becker, M., Belounnas, A., Blanco, A., Blume, C., Chlad, L., Chudoba, P., Ciepal, I., Cordts, M., Dreyer, J., Esmail, W. A., Fabbietti, L., Floersheimer, H., Fonte, P., Friese, J., Fröhlich, I., Förtsch, J., Galatyuk, T., Gniazdowski, T, Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Höhne, C., Hojeij, F., Holzmann, R., Huck, H., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Kornakov, G., Kotte, R., Kres, I., Krueger, W., Kugler, A., Lalik, R., Lebedev, S., Linev, S., Linz, F., Lopes, L., Lorenz, M., Malige, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Molenda, A., Müntz, C., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Pfeifer, D., Piasecki, K., Pietraszko, J., Povar, T., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Ritman, J., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Saraiva, J., Schild, N., Schwab, E., Scozzi, F., Seck, F., Selyuzhenkov, I., Singh, U., Skorpil, L., Smyrski, J., Spies, S., Stefaniak, M. S., Ströbele, H., Stroth, J., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Wagner, V., Wasiluk, M., Weber, A. A., Wendisch, C., Wirth, J., Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: The global polarization of {\Lambda} hyperons along the total orbital angular momentum of a relativistic heavy-ion collision is presented based on the high statistics data samples collected in Au+Au collisions at \sqrt{s_{NN}} = 2.4 GeV and Ag+Ag at 2.55 GeV with the High-Acceptance Di-Electron Spectrometer (HADES) at GSI, Darmstadt. This is the first measurement below the strangeness production threshold in nucleon-nucleon collisions. Results are reported as a function of the collision centrality as well as a function of the hyperon transverse momentum (p_T) and rapidity (y_{CM}) for the range of centrality 0--40%. We observe a strong centrality dependence of the polarization with an increasing signal towards peripheral collisions. For mid-central (20--40%) collisions the polarization magnitudes are (%) = 6.8 \pm 1.3 (stat.) \pm 2.1 (syst.) for Au+Au and (%) = 6.2 \pm 0.4 (stat.) \pm 0.6 (syst.) for Ag+Ag, which are the largest values observed so far. This observation thus provides a continuation of the increasing trend previously observed by STAR and contrasts expectations from recent theoretical calculations predicting a maximum in the region of collision energies about 3 GeV. The observed polarization is of a similar magnitude as predicted by 3D fluid dynamics and the UrQMD plus thermal vorticity model and significantly above results from the AMPT model., Comment: 8 pages, 4 figures
Published: 2022
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7. First measurement of massive virtual photon emission from N* baryon resonances

Author: Yassine, R. Abou, Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Becker, M., Behnke, C., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Chlad, L., Chudoba, P., Ciepal, I., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Förtsch, J., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Hojeij, F., Holzmann, R., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Lapidus, K., Linev, S., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Molenda, A., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K., Otto, J. -H., Parpottas, Y., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Pietraszko, J., Povar, T., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Rodriguez-Ramos, P., Rost, A., Salabura, P., Scheib, T., Schild, N., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Spataro, S., Spies, S., Stefaniak, M. S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Vazquez-Doce, O., Wagner, V., Weber, A. A., Wendisch, C., Wiebusch, M. G., Wirth, J., Zbroszczyk, H. P., Zherebtsova, E., Zumbruch, P., and Zetenyi, M.
Subjects: Nuclear Experiment
Abstract: First information on the timelike electromagnetic structure of baryons in the second resonance region has been obtained from measurements of invariant mass and angular distributions in the quasi-free reaction $\pi^- p \to nee$ at $\sqrt{s_{\pi^- p}}$ = 1.49 GeV with the High Acceptance Di-Electron Spectrometer (HADES) detector at GSI using the pion beam impinging on a CH$_2$ target. We find a total cross section $\sigma (\pi^- p \to nee) = 2.97 \pm 0.07^{data} \pm 0.21^{acc} \pm 0.31^{\rm{Z}_{\rm{eff}}} \mu$b. Combined with the Partial Wave Analysis of the concurrently measured two-pion channel, these data sets provide a crucial test of Vector Meson Dominance (VMD) inspired models. The commonly used "strict VMD" approach strongly overestimates the $e^+e^-$ yield. Instead, approaches based on a VMD amplitude vanishing at small $e^+e^-$ invariant masses supplemented coherently by a direct photon amplitude provide a better agreement. A good description of the data is also obtained using a calculation of electromagnetic timelike baryon transition form factors in a covariant spectator-quark model, demonstrating the dominance of meson cloud effects. The angular distributions of $e^+e^-$ pairs demonstrate the contributions of virtual photons with longitudinal polarization, in contrast to real photons. The virtual photon angular dependence supports the dominance of J=3/2, I=1/2 contributions observed in both the $\gamma^{\star} n$ and the $\pi \pi n$ channels., Comment: 8 pages, 3 figures
Published: 2022

8. Impact of the Coulomb field on charged-pion spectra in few-GeV heavy-ion collisions

Author: Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Ciepał, I., Deveaux, C., Dreyer, J., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kohls, M., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Linev, S., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Nabroth, M., Naumann, L., Nowakowski, K., Parpottas, Y., Parschau, M., Pechenov, V., Pechenova, O., Petukhov, O., Piasecki, K., Pietraszko, J., Przygoda, W., Pysz, K., Ramos, S., Ramstein, B., Rathod, N., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schild, N., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Sobolev, Yu. G., Spataro, S., Spies, S., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: In nuclear collisions the incident protons generate a Coulomb field which acts on produced charged particles. The impact of these interactions on charged pion transverse-mass and rapidity spectra, as well as on pion-pion momentum correlations is investigated in Au+Au collisions at $\sqrt{s_{NN}}$ = 2.4 GeV. We show that the low-mt part of the data ($m_t < 0.2$ GeV/c$^2$) can be well described with a Coulomb-modified Boltzmann distribution that also takes changes of the Coulomb field during the expansion of the fireball into account. The observed centrality dependence of the fitted mean Coulomb potential deviates strongly from a $A_{part}^{2/3}$ scaling, indicating that, next to the fireball, the non-interacting charged spectators have to be taken into account. For the most central collisions, the Coulomb modifications of the HBT source radii are found to be consistent with the potential extracted from the single-pion transverse-mass distributions. This finding suggests that the region of homogeneity obtained from two-pion correlations coincides with the region in which the pions freeze-out. Using the inferred mean-square radius of the charge distribution at freeze-out, we have deduced a baryon density, in fair agreement with values obtained from statistical hadronization model fits to the particle yields., Comment: 14 pages, 12 figures, to be published in EPJA
Published: 2022
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9. Prototype Design of a Timing and Fast Control system in the CBM Experiment

Author: Sidorenko, V., Fröhlich, I., Müller, W. F. J., Emschermann, D., Bähr, S., Sturm, C., and Becker, J.
Subjects: Physics - Instrumentation and Detectors
Abstract: The Compressed Baryonic Matter (CBM) experiment is designed to handle interaction rates of up to 10 MHz and up to 1 TB/s of raw data generated. With triggerless streaming data acquisition in the experiment and beam intensity fluctuations, it is expected that occasional data bursts will surpass bandwidth capabilities of the Data Acquisition System (DAQ) system. In order to preserve integrity of event data, the bandwidth of DAQ must be throttled in an organised way with minimum information loss. The Timing and Fast Control (TFC) system provides a latency-optimised datapath for throttling commands and distributes a system clock together with a global timestamp. This paper describes a prototype design of the system with focus on synchronisation and its evaluation.
Published: 2021
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10. Production and electromagnetic decay of hyperons: a feasibility study with HADES as a Phase-0 experiment at FAIR

Author: Adamczewski-Musch, J., Belyaev, A., Blanco, A., Blume, C., Charlotte, C., Borisenko, D. S., Chlad, L., Chudoba, P., Ciepał, I., Derichs, A., Dittert, D., Dreyer, J., Esmail, W. A., Fateev, O., Fonte, P., Friese, J., Fröhlich, I., Förtsch, J., Galatyuk, T., Georgadze, I., Golosov, O., Golubeva, M., Greifenhagen, R., Grunwald, M., Grzonka, D., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Heybeck, B., Höhne, C., Holona, M., Holzmann, R., Huck, H., Ierusalimov, A., Imre, M., Ivashkin, A., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Khomyakov, V., Koenig, I., Koenig, W., Kohls, M., Kornakov, G., Kornas, F., Kotte, R., Kozela, A., Kozlov, V., Kres, I., Kuboś, J., Kugler, A., Kulessa, P., Ladygin, V., Lalik, R., Galliard, C. Le, Lebedev, A., Lebedev, S., Linev, S., Lopes, L., Lorenz, M., Lykasov, G., Malige, A., Markert, J., Matulewicz, T., Michel, J., Morozov, S., Müntz, C., Naumann, L., Nowakowski, K., Orfanitsky, S., Otto, J. -H., Patel, V., Pauly, C., Pechenov, V., Pechenova, O., Andrade, G. Perez, Petukhov, O., Pfeifer, D., Piasecki, K., Pietraszko, J., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Regina, J., Reshetin, A., Reznikov, S., Rieger, J. T., Ritman, J., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Saraiva, J., Schild, N., Schwab, E., Schönning, K., Scozzi, F., Seck, F., Selyuzhenkov, I., Serdyuk, V., Shabanov, A., Singh, U., Smyrski, J., Sobiella, M., Spies, S., Strikhanov, M., Ströbele, H., Stroth, J., Sumara, K., Svoboda, O., Szala, M., Szewczyk, J., Taranenko, A., Tlusty, P., Traxler, M., Wagner, V., Wasiluk, M., Weber, A. A., Wendisch, C., Wintz, P., Włoch, B., Zbroszczyk, H. P., Zherebzova, E., Zhilin, A., Zinchenko, A., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: A feasibility study has been performed in order to investigate the performance of the HADES detector to measure the electromagnetic decays of the hyperon resonances $\Sigma(1385)^0$, $\Lambda(1405)$ and $\Lambda{\Lambda}(1520)$ as well as the production of double strange baryon systems $\Xi^-$ and $\Lambda\Lambda$ in p+p reactions at a beam kinetic energy of 4.5 GeV. The existing HADES detector will be upgraded by a new Forward Detector, which extends the detector acceptance into a range of polar angles that plays a crucial role for these investigations. The analysis of each channel is preceded by a consideration of the production cross-sections. Afterwards the expected signal count rates using a target consisting of either liquid hydrogen or polyethylene are summarized., Comment: Draft prepared by Rafa{\l} Lalik, James Ritman, Piotr Salabura, 19 pages, 21 figures, 4 tables
Published: 2020
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11. Directed, elliptic and higher order flow harmonics of protons, deuterons and tritons in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV

Author: HADES collaboration, Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Ciepal, I., Deveaux, C., Dreyer, J., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Golosov, O., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kohls, M., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Mamaev, M., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Piasecki, K., Pietraszko, J., Przygoda, W., Pysz, K., Ramos, S., Ramstein, B., Rathod, N., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Sobolev, Yu. G., Spataro, S., Spies, S., Ströbele, H., Stroth, J., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Wójcik, D., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: Flow coefficients $v_{n}$ of the orders $n = 1 - 6$ are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons and tritons as a function of centrality, transverse momentum and rapidity in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV. Combining the information from the flow coefficients of all orders allows to construct for the first time, at collision energies of a few GeV, a multi-differential picture of the angular emission pattern of these particles. It reflects the complicated interplay between the effect of the central fireball pressure on the emission of particles and their subsequent interaction with spectator matter. The high precision information on higher order flow coefficients is a major step forward in constraining the equation-of-state of dense baryonic matter., Comment: 6 pages, 5 figures; Figs. 2, 3 and 5 updated from re-analysis of data including UrQMD model predictions. Plotting error in Fig. 4 corrected; Accepted for publication in Phys. Rev. Lett
Published: 2020
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12. Charged pion production in $\mathbf{Au+Au}$ collisions at $\mathbf{\sqrt{s_{NN}}}$ = 2.4$\mathbf{GeV}$

Author: Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Boehmer, M., Bordalo, P., Chernenko, S., Chlad, L., Ciepal, I., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Glaessel, S., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kohls, M., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Muentz, C., Muenzer, R., Naumann, L., Nowakowski, K., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Piasecki, K., Pietraszko, J., Przygoda, W., Pysz, K., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rathod, N., Rosier, P., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Sobolev, Yu. G., Spataro, S., Spies, S., Stroebele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Wojcik, D., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: We present high-statistic data on charged pion emission from Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 2.4 GeV (corresponding to $E_{beam}$ = 1.23 A GeV) in four centrality classes in the range 0 - 40$\%$ of the most central collisions. The data are analyzed as a function of transverse momentum, transverse mass, rapidity, and polar angle. Pion multiplicity per participating nucleon decreases moderately with increasing centrality. The polar angular distributions are found to be non-isotropic even for the most central event class. Our results on pion multiplicity fit well into the general trend of the world data, but undershoot by $2.5 \sigma$ data from the FOPI experiment measured at slightly lower beam energy. We compare our data to state-of-the-art transport model calculations (PHSD, IQMD, PHQMD, GiBUU and SMASH) and find substantial differences between the measurement and the results of these calculations., Comment: 17 pages, 19 figures, 4 tables
Published: 2020
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13. Two-Pion production in the second resonance region in $\pi^- p$ collisions with HADES

Author: Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Chernenko, S., Chlad, L., Chudoba, P., Ciepał, I., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fateev, O., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kuboś, J., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Linev, S., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Prozorov, A. P., Przygoda, W., Ramstein, B., Rathod, N., Reshetin, A., Rodriguez-Ramos, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sing, U., Smyrski, J., Spataro, S., Spies, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Ungethüm, C., Vazquez-Doce, O., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Wójcik, D., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: Pion induced reactions provide unique opportunities for an unambiguous description of baryonic resonances and their coupling channels by means of a partial wave analysis. Using the secondary pion beam at SIS18, the two pion production in the second resonance region has been investigated to unravel the role of the $N(1520) \frac{3}{2}^-$ resonance in the intermediate $\rho$ production. Results on exclusive channels with one pion ($\pi^{-}p$) and two pions ($\pi^{+}\pi^{-}n$, $\pi^{0}\pi^{-}p$) in the final state measured in the $\pi^{-}-p$ reaction at four different pion beam momenta (0.650, 0.685, 0.733, and 0.786 GeV/c) are presented. The excitation function of the different partial waves and $\Delta\pi$, $N\sigma$ and $N\rho$ isobar configurations is obtained, using the Bonn-Gatchina partial wave analysis. The $N(1520) \frac{3}{2}^-$ resonance is found to dominate the $N\rho$ final state with the branching ratio $BR=12.2 \pm 1.9\%$.
Published: 2020
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14. Identical pion intensity interferometry at sqrt(s_{NN})=2.4 GeV

Author: Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Piasecki, K., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Spies, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Wójcik, D., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: High-statistics $\pi^-\pi^-$ and $\pi^+\pi^+$ femtoscopy data are presented for Au+Au collisions at $\sqrt{s_\mathrm{NN}}=2.4$ GeV, measured with HADES at SIS18/GSI. The experimental correlation functions allow the determination of the space-time extent of the corresponding emission sources via a comparison to models. The emission source, parametrized as three-dimensional Gaussian distribution, is studied in dependence on pair transverse momentum, azimuthal emission angle with respect to the reaction plane, collision centrality and beam energy. For all centralities and transverse momenta, a geometrical distribution of ellipsoidal shape is found in the plane perpendicular to the beam direction with the larger extension perpendicular to the reaction plane. For large transverse momenta, the corresponding eccentricity approaches the initial eccentricity. The eccentricity is smallest for most central collisions, where the shape is almost circular. The magnitude of the tilt angle of the emission ellipsoid in the reaction plane decreases with increasing centrality and increasing transverse momentum. All source radii increase with centrality, largely exhibiting a linear rise with the number of participants, irrespective of transverse momentum. A substantial charge-sign difference of the source radii is found, appearing most pronounced at low transverse momentum. The extracted source parameters are consistent with the extrapolation of their energy dependence down from higher energies., Comment: 20 pages, 19 figures, 7 tables. arXiv admin note: text overlap with arXiv:1811.06213
Published: 2019
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15. Sub-threshold production of K^{0}_{s} mesons and {\Lambda} hyperons in Au(1.23A GeV)+Au

Author: HADES collaboration, Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., Zumbruch, P., and Leifels, Y.
Subjects: Nuclear Experiment
Abstract: We present first data on sub-threshold production of K0 s mesons and {\Lambda} hyperons in Au+Au collisions at $\sqrt{s_{NN}}$ = 2.4 GeV. We observe an universal scaling of hadrons containing strangeness, independent of their corresponding production thresholds. Comparing the yields, their scaling, and the shapes of the rapidity and the pt spectra to state-of-the-art transport model (UrQMD, HSD, IQMD) predictions, we find that none of the latter can simultaneously describe all observables with reasonable \c{hi}2 values., Comment: 8 pages, 10 figures
Published: 2018
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16. Strong absorption of hadrons with hidden and open strangeness in nuclear matter

Author: Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Chernenko, S., Chlad, L., Chudoba, P., Ciepal, I., Deveaux, C., Dittert, D., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kubos, J., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Linev, S., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowsk, K., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Prozorov, A. P., Przygoda, W., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Smyrski, J., Spataro, S., Spies, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Ungethüm, C., Doce, O. Vazquez, Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: We present the first observation of K- and \phi absorption within nuclear matter by means of \pi- -induced reactions on C and W targets at an incident beam momentum of 1.7 GeV/c studied with HADES at SIS18/GSI. The double ratio (K-/K+)W / (K-/K+)C is found to be 0.319 \pm 0.009(stat)+0.014-0.012 (syst) indicating a larger absorption of K- in heavier targets as compared to lighter ones. The measured \phi/K- ratios in \pi-+C and \pi^- +W reactions within the HADES acceptance are found to be equal to $0.55 \pm 0.03(stat)+0.06-0.07$ (syst) and to $0.63 \pm 0.05(stat)-0.11+0.11$ (syst), respectively. The similar ratios measured in the two different reactions demonstrate for the first time experimentally that the dynamics of the \phi meson in nuclear medium is strongly coupled to the K- dynamics. The large difference in the \phi production off C and W nuclei is discussed in terms of a strong \phiN in-medium coupling., Comment: 6 pages, 3 figures
Published: 2018
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17. Identical pion intensity interferometry in central Au+Au collisions at 1.23A GeV

Author: Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Kühn, W., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Piasecki, K., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Wojcik, D., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: We investigate identical pion HBT intensity interferometry for central Au+Au collisions at 1.23A GeV. High-statistics $\pi^-\pi^-$ and $\pi^+\pi^+$ data are measured with HADES at SIS18/GSI. The radius parameters, derived from the correlation function depending on relative momenta in the longitudinal-comoving system and parametrized as three-dimensional Gaussian distribution, are studied as function of transverse momentum. A substantial charge-sign difference of the source radii is found, particularly pronounced at low transverse momentum. The extracted Coulomb-corrected source parameters agree well with a smooth extrapolation of the center-of-mass energy dependence established at higher energies, extending the corresponding excitation functions down towards a very low energy. Our data would thus rather disfavour any strong energy dependence of the radius parameters in the low energy region., Comment: 7 pages, 5 figures, updated author and grant lists
Published: 2018
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18. Centrality determination of Au+Au collisions at 1.23A GeV with HADES

Author: HADES collaboration, Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Hoehne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kaempfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Kuehn, W., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Muentz, C., Muenzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Stroebele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: The centrality determination for Au+Au collisions at 1.23A GeV, as measured with HADES at the GSI-SIS18, is described. In order to extract collision geometry related quantities, such as the average impact parameter or number of participating nucleons, a Glauber Monte Carlo approach is employed. For the application of this model to collisions at this relatively low centre-of-mass energy of $\sqrt{s_{\mathrm{NN}}} = 2.42$ GeV special investigations were performed. As a result a well defined procedure to determine centrality classes for ongoing analyses of heavy-ion data is established.
Published: 2017
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19. $\Sigma^0$ production in proton nucleus collisions near threshold

Author: Adamczewski-Musch, J., Agakishiev, G., Arnold, O., Atomssa, E. T., Behnke, C., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Chernenko, P. Bordalo S., Deveaux, C., Dybczak, A., Epple, E., Fabbietti, L., Fonte, O. Fateev P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gill, K., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Hlavac, T. Hennino S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, M. Jurkovic B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krása, A., Krebs, E., Kuc, H., Kunz, A. Kugler T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Maurus, S., Mangiarotti, A., Markert, J., Metag, V., Michel, J., Müntz, C., Naumann, R. Münzer L., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petousis, V., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Rehnisch, L., Reshetin, A., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schmidt-Sommerfeld, K., Schuldes, H., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Tsertos, H., Vasiliev, T., Wagner, V., Wendisch, C., Wirth, J., Wüstenfeld, J., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: The production of $\Sigma^{0}$ baryons in the nuclear reaction p (3.5 GeV) + Nb (corresponding to $\sqrt{s_{NN}}=3.18$ GeV) is studied with the detector set-up HADES at GSI, Darmstadt. $\Sigma^{0}$s were identified via the decay $\Sigma^{0} \rightarrow \Lambda \gamma$ with subsequent decays $\Lambda \rightarrow p \pi^{-}$ in coincidence with a $e^{+}e^{-}$ pair from either external ($\gamma \rightarrow e^{+} e^{-}$) or internal (Dalitz decay $\gamma^{*}\rightarrow e^{+} e^{-}$) gamma conversions. The differential $\Sigma^0$ cross section integrated over the detector acceptance, i.e. the rapidity interval $0.5 < y < 1.1$, has been extracted as $\Delta\sigma_{\Sigma^{0}} = 2.3 \pm (0.2)^{stat} \pm \left(^{+0.6}_{-0.6}\right)^{sys} \pm (0.2)^{norm}$ mb, yielding the inclusive production cross section in full phase space $\sigma^{total}_{\Sigma^{0}} = 5.8 \pm (0.5)^{stat} \pm \left(^{+1.4}_{-1.4}\right)^{sys} \pm (0.6)^{norm} \pm (1.7)^{extrapol}$ mb by averaging over different extrapolation methods. The $\Lambda_{all}$/$\Sigma^{0}$ ratio within the HADES acceptance is equal to 2.3 $\pm$ $(0.2)^{stat}$ $\pm$ $(^{+0.6}_{-0.6})^{sys}$. The obtained rapidity and momentum distributions are compared to transport model calculations. The $\Sigma^{0}$ yield agrees with the statistical model of particle production in nuclear reactions., Comment: 7 pages, 5 figures
Published: 2017
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20. Analysis of pion production data measured by HADES in proton-proton collisions at 1.25 GeV

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Müntz, C., Münzer, R., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., Sarantsev, A. V., and Nikonov, V. A.
Subjects: Nuclear Experiment, J.2
Abstract: Baryon resonance production in proton-proton collisions at a kinetic beam energy of 1.25 GeV is investigated. The multi-differential data were measured by the HADES collaboration. Exclusive channels with one pion in the final state ($np\pi^{+}$ and $pp\pi^{0}$) were put to extended studies based on various observables in the framework of a one-pion exchange model and with solutions obtained within the framework of a partial wave analysis (PWA) of the Bonn-Gatchina group. The results of the PWA confirm the dominant contribution of the $\Delta$(1232), yet with a sizable impact of the $N$(1440) and non-resonant partial waves., Comment: 12 pages, 6 figures
Published: 2017
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21. Analysis of the exclusive final state npe$^+$e$^-$ in quasi-free np reaction

Author: Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Finocchiaro, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Kühn, W., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Maurus, S., Metag, V., Michel, J., Morinière, E., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., Zumbruch, P., and Sarantsev, A. V.
Subjects: Nuclear Experiment, J.2
Abstract: We report on the investigation of dielectron production in tagged quasi-free neutron-proton collisions by using a deuteron beam of kinetic energy 1.25 GeV/u inpinging on a liquid hydrogen target. Our measurements with HADES confirm a significant excess of $e^+e^-$ pairs above the $\pi^{0}$ mass in the exclusive channel $dp \to npe^{+}e^{-}(p_{spect})$ as compared to the exclusive channel $ppe^{+}e^{-}$ measured in proton-proton collisions at the same energy. That excess points to different bremsstrahlung production mechanisms. Two models were evaluated for the role of the charged pion exchange between nucleons and double-$\Delta$ excitation combined with intermediate $\rho$-meson production. Differential cross sections as a function of the $e^+e^-$ invariant mass and of the angles of the virtual photon, proton and electrons provide valuable constraints and encourage further investigations on both experimental and theoretical side., Comment: 12 pages, 7 figures
Published: 2017
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22. Deep sub-threshold {\phi} production and implications for the K+/K- freeze-out in Au+Au collisions

Author: Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcy, G., Kornakov, G., Kotte, R., Kühn, W., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: We present data on charged kaons (K+-) and {\phi} mesons in Au(1.23A GeV)+Au collisions. It is the first simultaneous measurement of K and {\phi} mesons in central heavy-ion collisions below a kinetic beam energy of 10A GeV. The {\phi}/K- multiplicity ratio is found to be surprisingly high with a value of 0.52 +- 0.16 and shows no dependence on the centrality of the collision. Consequently, the different slopes of the K+ and K- transverse-mass spectra can be explained solely by feed- down, which substantially softens the spectra of K- mesons. Hence, in contrast to the commonly adapted argumentation in literature, the different slopes do not necessarily imply diverging freeze- out temperatures of K+ and K- mesons caused by different couplings to baryons., Comment: Corrected and updated version, 28 November 2017
Published: 2017
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23. $\Delta$(1232) Dalitz decay in proton-proton collisions at T=1.25 GeV measured with HADES

Author: Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Finocchiaro, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Kühn, W., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Mangiarotti, A., Markert, J., Maurus, S., Metag, V., Michel, J., Morinière, E., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Nowakowski, K. N., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petukhov, O., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., Zumbruch, P., and Sarantsev, A. V.
Subjects: Nuclear Experiment, J.2
Abstract: We report on the investigation of $\Delta$(1232) production and decay in proton-proton collisions at a kinetic energy of 1.25 GeV measured with HADES. Exclusive dilepton decay channels $ppe^{+}e^{-}$ and $ppe^{+}e^{-}\gamma$ have been studied and compared with the partial wave analysis of the hadronic $pp\pi^{0}$ channel. They allow to access both $\Delta^+ \to p\pi^0(e^+e^-\gamma)$ and $\Delta^+ \to pe^+e^-$ Dalitz decay channels. The perfect reconstruction of the well known $\pi^0$ Dalitz decay serves as a proof of the consistency of the analysis. The $\Delta$ Dalitz decay is identified for the first time and the sensitivity to N-$\Delta$ transition form factors is tested. The $\Delta$(1232) Dalitz decay branching ratio is also determined for the first time; our result is (4.19 $\pm$ 0.62 syst. $\pm$ 0.34 stat.) $\times $ 10$^{-5}$, albeit with some model dependence., Comment: 13 pages, 7 figures
Published: 2017
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24. Inclusive {\Lambda} production in proton-proton collisions at 3.5 GeV

Author: Adamczewski-Musch, J., Agakishiev, G., Arnold, O., Atomssa, E. T., Behnke, C., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Deveaux, C., Dreyer, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gill, K., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krása, A., Krebs, E., Kuc, H., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Maurus, S., Mangiarotti, A., Markert, J., Metag, V., Michel, J., Morozov, S., Müntz, C., Münzer, R., Naumann, L., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petousis, V., Pietraszko, J., Przygoda, W., Ramos, S., Ramstein, B., Rehnisch, L., Reshetin, A., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schmidt-Sommerfeld, K., Schuldes, H., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataroe, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Tsertos, H., Vasiliev, T., Wagner, V., Wendisch, C., Wirth, J., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: The inclusive production of {\Lambda} hyperons in proton-proton collisions at $\sqrt{s}$ = 3.18 GeV was measured with HADES at the GSI Helmholtzzentrum f\"ur Schwerionenforschung in Darmstadt. The experimental data are compared to a data-based model for individual exclusive {\Lambda} production channels in the same reaction. The contributions of intermediate resonances such as {\Sigma}(1385), {\Delta}++ or N* are considered in detail. In particular, the result of a partial wave analysis is accounted for the abundant pK$^+${\Lambda} final state. Model and data show a reasonable agreement at mid rapidities, while a difference is found for larger rapidities. A total {\Lambda} production cross section in p+p collisions at $\sqrt{s}$ = 3.18 GeV of {\sigma}(pp $\to$ {\Lambda} + X) = 207.3 $\pm$ 1.3 +6.0 -7.3 (stat.) $\pm$ 8.4 (syst.) +0.4 -0.5 (model) {\mu}b is found., Comment: 12 pages, 6 figures
Published: 2016
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25. Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

Author: CBM Collaboration, Ablyazimov, T., Abuhoza, A., Adak, R. P., Adamczyk, M., Agarwal, K., Aggarwal, M. M., Ahammed, Z., Ahmad, F., Ahmad, N., Ahmad, S., Akindinov, A., Akishin, P., Akishina, E., Akishina, T., Akishina, V., Akram, A., Al-Turany, M., Alekseev, I., Alexandrov, E., Alexandrov, I., Amar-Youcef, S., Anđelić, M., Andreeva, O., Andrei, C., Andronic, A., Anisimov, Yu., Appelshäuser, H., Argintaru, D., Atkin, E., Avdeev, S., Averbeck, R., Azmi, M. D., Baban, V., Bach, M., Badura, E., Bähr, S., Balog, T., Balzer, M., Bao, E., Baranova, N., Barczyk, T., Bartoş, D., Bashir, S., Baszczyk, M., Batenkov, O., Baublis, V., Baznat, M., Becker, J., Becker, K. -H., Belogurov, S., Belyakov, D., Bendarouach, J., Berceanu, I., Bercuci, A., Berdnikov, A., Berdnikov, Y., Berendes, R., Berezin, G., Bergmann, C., Bertini, D., Bertini, O., Beşliu, C., Bezshyyko, O., Bhaduri, P. P., Bhasin, A., Bhati, A. K., Bhattacharjee, B., Bhattacharyya, A., Bhattacharyya, T. K., Biswas, S., Blank, T., Blau, D., Blinov, V., Blume, C., Bocharov, Yu., Book, J., Breitner, T., Brüning, U., Brzychczyk, J., Bubak, A., Büsching, H., Bus, T., Butuzov, V., Bychkov, A., Byszuk, A., Cai, Xu, Cálin, M., Cao, Ping, Caragheorgheopol, G., Carević, I., Cătănescu, V., Chakrabarti, A., Chattopadhyay, S., Chaus, A., Chen, Hongfang, Chen, LuYao, Cheng, Jianping, Chepurnov, V., Cherif, H., Chernogorov, A., Ciobanu, M. I., Claus, G., Constantin, F., Csanád, M., D'Ascenzo, N., Das, Supriya, Das, Susovan, de Cuveland, J., Debnath, B., Dementiev, D., Deng, Wendi, Deng, Zhi, Deppe, H., Deppner, I., Derenovskaya, O., Deveaux, C. A., Deveaux, M., Dey, K., Dey, M., Dillenseger, P., Dobyrn, V., Doering, D., Dong, Sheng, Dorokhov, A., Dreschmann, M., Drozd, A., Dubey, A. K., Dubnichka, S., Dubnichkova, Z., Dürr, M., Dutka, L., Dželalija, M., Elsha, V. V., Emschermann, D., Engel, H., Eremin, V., Eşanu, T., Eschke, J., Eschweiler, D., Fan, Huanhuan, Fan, Xingming, Farooq, M., Fateev, O., Feng, Shengqin, Figuli, S. P. D., Filozova, I., Finogeev, D., Fischer, P., Flemming, H., Förtsch, J., Frankenfeld, U., Friese, V., Friske, E., Fröhlich, I., Frühauf, J., Gajda, J., Galatyuk, T., Gangopadhyay, G., Chávez, C. García, Gebelein, J., Ghosh, P., Ghosh, S. K., Gläßel, S., Goffe, M., Golinka-Bezshyyko, L., Golovatyuk, V., Golovnya, S., Golovtsov, V., Golubeva, M., Golubkov, D., Ramírez, A. Gómez, Gorbunov, S., Gorokhov, S., Gottschalk, D., Gryboś, P., Grzeszczuk, A., Guber, F., Gudima, K., Gumiński, M., Gupta, A., Gusakov, Yu., Han, Dong, Hartmann, H., He, Shue, Hehner, J., Heine, N., Herghelegiu, A., Herrmann, N., Heß, B., Heuser, J. M., Himmi, A., Höhne, C., Holzmann, R., Hu, Dongdong, Huang, Guangming, Huang, Xinjie, Hutter, D., Ierusalimov, A., Ilgenfritz, E. -M., Irfan, M., Ivanischev, D., Ivanov, M., Ivanov, P., Ivanov, Valery, Ivanov, Victor, Ivanov, Vladimir, Ivashkin, A., Jaaskelainen, K., Jahan, H., Jain, V., Jakovlev, V., Janson, T., Jiang, Di, Jipa, A., Kadenko, I., Kähler, P., Kämpfer, B., Kalinin, V., Kallunkathariyil, J., Kampert, K. -H., Kaptur, E., Karabowicz, R., Karavichev, O., Karavicheva, T., Karmanov, D., Karnaukhov, V., Karpechev, E., Kasiński, K., Kasprowicz, G., Kaur, M., Kazantsev, A., Kebschull, U., Kekelidze, G., Khan, M. M., Khan, S. A., Khanzadeev, A., Khasanov, F., Khvorostukhin, A., Kirakosyan, V., Kirejczyk, M., Kiryakov, A., Kiš, M., Kisel, I., Kisel, P., Kiselev, S., Kiss, T., Klaus, P., Kłeczek, R., Klein-Bösing, Ch., Kleipa, V., Klochkov, V., Kmon, P., Koch, K., Kochenda, L., Koczoń, P., Koenig, W., Kohn, M., Kolb, B. W., Kolosova, A., Komkov, B., Korolev, M., Korolko, I., Kotte, R., Kovalchuk, A., Kowalski, S., Koziel, M., Kozlov, G., Kozlov, V., Kramarenko, V., Kravtsov, P., Krebs, E., Kreidl, C., Kres, I., Kresan, D., Kretschmar, G., Krieger, M., Kryanev, A. V., Kryshen, E., Kuc, M., Kucewicz, W., Kucher, V., Kudin, L., Kugler, A., Kumar, Ajit, Kumar, Ashwini, Kumar, L., Kunkel, J., Kurepin, A., Kurepin, N., Kurilkin, A., Kurilkin, P., Kushpil, V., Kuznetsov, S., Kyva, V., Ladygin, V., Lara, C., Larionov, P., García, A. Laso, Lavrik, E., Lazanu, I., Lebedev, A., Lebedev, S., Lebedeva, E., Lehnert, J., Lehrbach, J., Leifels, Y., Lemke, F., Li, Cheng, Li, Qiyan, Li, Xin, Li, Yuanjing, Lindenstruth, V., Linnik, B., Liu, Feng, Lobanov, I., Lobanova, E., Löchner, S., Loizeau, P. -A., Lone, S. A., Martínez, J. A. Lucio, Luo, Xiaofeng, Lymanets, A., Lyu, Pengfei, Maevskaya, A., Mahajan, S., Mahapatra, D. P., Mahmoud, T., Maj, P., Majka, Z., Malakhov, A., Malankin, E., Malkevich, D., Malyatina, O., Malygina, H., Mandal, M. M., Mandal, S., Manko, V., Manz, S., Garcia, A. M. Marin, Markert, J., Masciocchi, S., Matulewicz, T., Meder, L., Merkin, M., Mialkovski, V., Michel, J., Miftakhov, N., Mik, L., Mikhailov, K., Mikhaylov, V., Milanović, B., Militsija, V., Miskowiec, D., Momot, I., Morhardt, T., Morozov, S., Müller, W. F. J., Müntz, C., Mukherjee, S., Castillo, C. E. Muńoz, Murin, Yu., Najman, R., Nandi, C., Nandy, E., Naumann, L., Nayak, T., Nedosekin, A., Negi, V. S., Niebur, W., Nikulin, V., Normanov, D., Oancea, A., Oh, Kunsu, Onishchuk, Yu., Ososkov, G., Otfinowski, P., Ovcharenko, E., Pal, S., Panasenko, I., Panda, N. R., Parzhitskiy, S., Patel, V., Pauly, C., Penschuck, M., Peshekhonov, D., Peshekhonov, V., Petráček, V., Petri, M., Petriş, M., Petrovici, A., Petrovici, M., Petrovskiy, A., Petukhov, O., Pfeifer, D., Piasecki, K., Pieper, J., Pietraszko, J., Płaneta, R., Plotnikov, V., Plujko, V., Pluta, J., Pop, A., Pospisil, V., Poźniak, K., Prakash, A., Prasad, S. K., Prokudin, M., Pshenichnov, I., Pugach, M., Pugatch, V., Querchfeld, S., Rabtsun, S., Radulescu, L., Raha, S., Rami, F., Raniwala, R., Raniwala, S., Raportirenko, A., Rautenberg, J., Rauza, J., Ray, R., Razin, S., Reichelt, P., Reinecke, S., Reinefeld, A., Reshetin, A., Ristea, C., Ristea, O., Rodriguez, A. Rodriguez, Roether, F., Romaniuk, R., Rost, A., Rostchin, E., Rostovtseva, I., Roy, Amitava, Roy, Ankhi, Rożynek, J., Ryabov, Yu., Sadovsky, A., Sahoo, R., Sahu, P. K., Sahu, S. K., Saini, J., Samanta, S., Sambyal, S. S., Samsonov, V., Rosado, J. Sánchez, Sander, O., Sarangi, S., Satława, T., Sau, S., Saveliev, V., Schatral, S., Schiaua, C., Schintke, F., Schmidt, C. J., Schmidt, H. R., Schmidt, K., Scholten, J., Schweda, K., Seck, F., Seddiki, S., Selyuzhenkov, I., Semennikov, A., Senger, A., Senger, P., Shabanov, A., Shabunov, A., Shao, Ming, Sheremetiev, A. D., Shi, Shusu, Shumeiko, N., Shumikhin, V., Sibiryak, I., Sikora, B., Simakov, A., Simon, C., Simons, C., Singaraju, R. N., Singh, A. K., Singh, B. K., Singh, C. P., Singhal, V., Singla, M., Sitzmann, P., Siwek-Wilczyńska, K., Škoda, L., Skwira-Chalot, I., Som, I., Song, Guofeng, Song, Jihye, Sosin, Z., Soyk, D., Staszel, P., Strikhanov, M., Strohauer, S., Stroth, J., Sturm, C., Sultanov, R., Sun, Yongjie, Svirida, D., Svoboda, O., Szabó, A., Szczygieł, R., Talukdar, R., Tang, Zebo, Tanha, M., Tarasiuk, J., Tarassenkova, O., Târzilă, M. -G., Teklishyn, M., Tischler, T., Tlustý, P., Tölyhi, T., Toia, A., Topil'skaya, N., Träger, M., Tripathy, S., Tsakov, I., Tsyupa, Yu., Turowiecki, A., Tuturas, N. G., Uhlig, F., Usenko, E., Valin, I., Varga, D., Vassiliev, I., Vasylyev, O., Verbitskaya, E., Verhoeven, W., Veshikov, A., Visinka, R., Viyogi, Y. P., Volkov, S., Volochniuk, A., Vorobiev, A., Voronin, Aleksey, Voronin, Alexander, Vovchenko, V., Vznuzdaev, M., Wang, Dong, Wang, Xi-Wei, Wang, Yaping, Wang, Yi, Weber, M., Wendisch, C., Wessels, J. P., Wiebusch, M., Wiechula, J., Wielanek, D., Wieloch, A., Wilms, A., Winckler, N., Winter, M., Wiśniewski, K., Wolf, Gy., Won, Sanguk, Wu, Ke-Jun, Wüstenfeld, J., Xiang, Changzhou, Xu, Nu, Yang, Junfeng, Yang, Rongxing, Yin, Zhongbao, Yoo, In-Kwon, Yuldashev, B., Yushmanov, I., Zabołotny, W., Zaitsev, Yu., Zamiatin, N. I., Zanevsky, Yu., Zhalov, M., Zhang, Yifei, Zhang, Yu, Zhao, Lei, Zheng, Jiajun, Zheng, Sheng, Zhou, Daicui, Zhou, Jing, Zhu, Xianglei, Zinchenko, A., Zipper, W., Żoładź, M., Zrelov, P., Zryuev, V., Zumbruch, P., and Zyzak, M.
Subjects: Nuclear Experiment
Abstract: Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (mu_B > 500 MeV), effects of chiral symmetry, and the equation-of-state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2022, in the context of the worldwide efforts to explore high-density QCD matter., Comment: 15 pages, 11 figures. Published in European Physical Journal A
Published: 2016
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26. The $\bf{\Lambda p}$ interaction studied via femtoscopy in p + Nb reactions at $\mathbf{\sqrt{s_{NN}}=3.18} ~\mathrm{\bf{GeV}}$

Author: Adamczewski-Musch, J., Agakishiev, G., Arnold, O., Atomssa, E. T., Behnke, C., Berger-Chen, J. C., Biernat, J., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Deveaux, C., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gill, K., Golubeva, M., Guber, F., Gumberidze, M., Harabasz, S., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krasa, A., Krebs, E., Kuc, H., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Maurus, S., Mangiarotti, A., Markert, J., Metag, V., Müntz, J. Michel C., Münzer, R., Naumann, L., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petousis, V., Pietraszko, J., Przygoda, W., Ramstein, B., Rehnisch, L., Reshetin, A., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schmidt-Sommerfeld, K., Schuldes, H., Sellheim, P., Siebenson, J., Silva, L., Sobolev, Yu. G., Spataro, S., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Svoboda, O., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Tsertos, H., Vasiliev, T., Wagner, V., Wendisch, C., Wirth, J., Wüstenfeld, J., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: We report on the first measurement of $p\Lambda$ and $pp$ correlations via the femtoscopy method in p+Nb reactions at $\mathrm{\sqrt{s_{NN}}=3.18} ~\mathrm{GeV}$, studied with the High Acceptance Di-Electron Spectrometer (HADES). By comparing the experimental correlation function to model calculations, a source size for $pp$ pairs of $r_{0,pp}=2.02 \pm 0.01(\mathrm{stat})^{+0.11}_{-0.12} (\mathrm{sys}) ~\mathrm{fm}$ and a slightly smaller value for $p\Lambda$ of $r_{0,\Lambda p}=1.62 \pm 0.02(\mathrm{stat})^{+0.19}_{-0.08}(\mathrm{sys}) ~\mathrm{fm}$ is extracted. Using the geometrical extent of the particle emitting region, determined experimentally with $pp$ correlations as reference together with a source function from a transport model, it is possible to study different sets of scattering parameters. The $p\Lambda$ correlation is proven sensitive to predicted scattering length values from chiral effective field theory. We demonstrate that the femtoscopy technique can be used as valid alternative to the analysis of scattering data to study the hyperon-nucleon interaction., Comment: 12 pages, 11 figures
Published: 2016
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27. Statistical model analysis of hadron yields in proton-nucleus and heavy-ion collisions at SIS 18 energies

Author: Agakishiev, G., Arnold, O., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Gilardi, C., Göbel, K., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krasa, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lange, J. S., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Moriniere, E., Mousa, J., Müntz, C., Münzer, R., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Rehnisch, L., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schmah, A., Schuldes, H., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment, High Energy Physics - Experiment, Nuclear Theory
Abstract: The HADES data from p+Nb collisions at center of mass energy of $\sqrt{s_{NN}}$= 3.2 GeV are analyzed by employing a statistical model. Accounting for the identified hadrons $\pi^0$, $\eta$, $\Lambda$, $K^{0}_{s}$, $\omega$ allows a surprisingly good description of their abundances with parameters $T_{chem}=(99\pm11)$ MeV and $\mu_{b}=(619\pm34)$ MeV, which fits well in the chemical freeze-out systematics found in heavy-ion collisions. In supplement we reanalyze our previous HADES data from Ar+KCl collisions at $\sqrt{s_{NN}}$= 2.6 GeV with an updated version of the statistical model. We address equilibration in heavy-ion collisions by testing two aspects: the description of yields and the regularity of freeze-out parameters from a statistical model fit. Special emphasis is put on feed-down contributions from higher-lying resonance states which have been proposed to explain the experimentally observed $\Xi^-$ excess present in both data samples.
Published: 2015

28. K*(892)+ production in proton-proton collisions at E_beam = 3.5 GeV

Author: HADES Collaboration, Agakishiev, G., Arnold, O., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kunz, T., Kurepin, A., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michel, J., Mihaylov, D., Müntz, C., Münzer, R., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Svoboda, O., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment
Abstract: We present results on the K*(892)+ production in proton-proton collisions at a beam energy of E = 3.5 GeV, which is hitherto the lowest energy at which this mesonic resonance has been observed in nucleon-nucleon reactions. The data are interpreted within a two-channel model that includes the 3-body production of K*(892)+ associated with the Lambda- or Sigma-hyperon. The relative contributions of both channels are estimated. Besides the total cross section sigma(p+p -> K*(892)+ + X) = 9.5 +- 0.9 +1.1 -0.9 +- 0.7 mub, that adds a new data point to the excitation function of the K*(892)+ production in the region of low excess energy, transverse momenta and angular spectra are extracted and compared with the predictions of the two-channel model. The spin characteristics of K*(892)+ are discussed as well in terms of the spin-alignment., Comment: 7 pages, 9 figures, 1 table
Published: 2015
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29. Study of the quasi-free $np \to np \pi^+\pi^-$ reaction with a deuterium beam at 1.25 GeV/nucleon

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Díaz, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., Kühn, W., Kugler, A., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Vasiliev, T., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., and Zhou, P.
Subjects: Nuclear Experiment
Abstract: The tagged quasi-free $np \to np\pi^+\pi^-$ reaction has been studied experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI at a deuteron incident beam energy of 1.25 GeV/nucleon ($\sqrt s \sim$ 2.42 GeV/c for the quasi-free collision). For the first time, differential distributions for $\pi^{+}\pi^{-}$ production in $np$ collisions have been collected in the region corresponding to the large transverse momenta of the secondary particles. The invariant mass and angular distributions for the $np\rightarrow np\pi^{+}\pi^{-}$ reaction are compared with different models. This comparison confirms the dominance of the $t$-channel with $\Delta\Delta$ contribution. It also validates the changes previously introduced in the Valencia model to describe two-pion production data in other isospin channels, although some deviations are observed, especially for the $\pi^{+}\pi^{-}$ invariant mass spectrum. The extracted total cross section is also in much better agreement with this model. Our new measurement puts useful constraints for the existence of the conjectured dibaryon resonance at mass M$\sim$ 2.38 GeV and with width $\Gamma\sim$ 70 MeV.
Published: 2015
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30. Subthreshold Xi- Production in Collisions of p(3.5 GeV)+Nb

Author: Agakishiev, G., Arnold, O., Balanda, A., Belver, D., Belyaev, A. V., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krasa, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Müntz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y. V.
Subjects: Nuclear Experiment
Abstract: Results on the production of the double-strange cascade hyperon $\mathrm{\Xi^-}$ are reported for collisions of p\,(3.5~GeV)\,+\,Nb, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18 at GSI Helmholtzzentrum for Heavy-Ion Research, Darmstadt. For the first time, subthreshold $\mathrm{\Xi^-}$ production is observed in proton-nucleus interactions. Assuming a $\mathrm{\Xi^-}$ phase-space distribution similar to that of $\mathrm{\Lambda}$ hyperons, the production probability amounts to $P_{\mathrm{\Xi^-}}=(2.0\,\pm0.4\,\mathrm{(stat)}\,\pm 0.3\,\mathrm{(norm)}\,\pm 0.6\,\mathrm{(syst)})\times10^{-4}$ resulting in a $\mathrm{\Xi^-/(\Lambda+\Sigma^0)}$ ratio of $P_{\mathrm{\Xi^-}}/\ P_{\mathrm{\Lambda+\Sigma^0}}=(1.2\pm 0.3\,\mathrm{(stat)}\pm0.4\,\mathrm{(syst)})\times10^{-2}$. Available model predictions are significantly lower than the estimated $\mathrm{\Xi^-}$ yield., Comment: 6 pages, 3 figures
Published: 2015
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31. Partial Wave Analysis of the Reaction $p(3.5 GeV)+p \to pK^+\Lambda$ to Search for the '$ppK^-$' Bound State

Author: Agakishiev, G., Arnold, O., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krasa, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kunz, T., Kurepin, A., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michel, J., Müntz, C., Münzer, R., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., and Sarantsev, A. V.
Subjects: Nuclear Experiment
Abstract: Employing the Bonn-Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction $p(3.5GeV)+p\to pK^{+}\Lambda$. This reaction might contain information about the kaonic cluster "$ppK^-$" via its decay into $p\Lambda$. Due to interference effects in our coherent description of the data, a hypothetical $\overline{K}NN$ (or, specifically "$ppK^-$") cluster signal must not necessarily show up as a pronounced feature (e.g. a peak) in an invariant mass spectra like $p\Lambda$. Our PWA analysis includes a variety of resonant and non-resonant intermediate states and delivers a good description of our data (various angular distributions and two-hadron invariant mass spectra) without a contribution of a $\overline{K}NN$ cluster. At a confidence level of CL$_{s}$=95\% such a cluster can not contribute more than 2-12\% to the total cross section with a $pK^{+}\Lambda$ final state, which translates into a production cross-section between 0.7 $\mu b$ and 4.2 $\mu b$, respectively. The range of the upper limit depends on the assumed cluster mass, width and production process., Comment: 7 Pages, 5 Figures
Published: 2014
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32. Medium effects in proton-induced $K^{0}$ production at 3.5 GeV

Author: Agakishiev, G., Arnold, O., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kunz, T., Kurepin, A., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michel, J., Müntz, C., Münzer, R., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., Gaitanos, . T., and Weil, J.
Subjects: Nuclear Experiment
Abstract: We present the analysis of the inclusive $K^{0}$ production in p+p and p+Nb collisions measured with the HADES detector at a beam kinetic energy of 3.5 GeV. Data are compared to the GiBUU transport model. The data suggest the presence of a repulsive momentum-dependent kaon potential as predicted by the Chiral Perturbation Theory (ChPT). For the kaon at rest and at normal nuclear density, the ChPT potential amounts to $\approx 35$ MeV. A detailed tuning of the kaon production cross sections implemented in the model has been carried out to reproduce the experimental data measured in p+p collisions. The uncertainties in the parameters of the model were examined with respect to the sensitivity of the experimental results from p+Nb collisions to the in-medium kaon potential., Comment: 13 pages, 14 figures
Published: 2014
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33. Lambda hyperon production and polarization in collisions of p(3.5 GeV) + Nb

Author: Agakishiev, G., Arnold, O., Balanda, A., Belver, D., Belyaev, A. V., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., Gonzalez-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krasa, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Müntz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y. V.
Subjects: Nuclear Experiment
Abstract: Results on $\Lambda$ hyperon production are reported for collisions of p(3.5 GeV) + Nb, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18 at GSI Helmholtzzentrum for Heavy-Ion Research, Darmstadt. The transverse mass distributions in rapidity bins are well described by Boltzmann shapes with a maximum inverse slope parameter of about $90\,$MeV at a rapidity of $y=1.0$, i.e. slightly below the center-of-mass rapidity for nucleon-nucleon collisions, $y_{cm}=1.12$. The rapidity density decreases monotonically with increasing rapidity within a rapidity window ranging from 0.3 to 1.3. The $\Lambda$ phase-space distribution is compared with results of other experiments and with predictions of two transport approaches which are available publicly. None of the present versions of the employed models is able to fully reproduce the experimental distributions, i.e. in absolute yield and in shape. Presumably, this finding results from an insufficient modelling in the transport models of the elementary processes being relevant for $\Lambda$ production, rescattering and absorption. The present high-statistics data allow for a genuine two-dimensional investigation as a function of phase space of the self-analyzing $\Lambda$ polarization in the weak decay $\Lambda\rightarrow p \pi^-$. Finite negative values of the polarization in the order of $5-20\,\%$ are observed over the entire phase space studied. The absolute value of the polarization increases almost linearly with increasing transverse momentum for $p_t>300\,$MeV/c and increases with decreasing rapidity for $y < 0.8$., Comment: accepted by Eur. Phys. J. A
Published: 2014
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34. Associate K^0 production in p+p collisions at 3.5 GeV: The role of Delta(1232)++

Author: Agakishiev, G., Arnold, O., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kunz, T., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Münzer, R., Müntz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wustenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment
Abstract: An exclusive analysis of the 4-body final states $\mathrm{\Lambda + p + \pi^{+} + K^{0}}$ and $\mathrm{\Sigma^{0} + p + \pi^{+} + K^{0}}$ measured with HADES for p+p collisions at a beam kinetic energy of 3.5 GeV is presented. The analysis uses various phase space variables, such as missing mass and invariant mass distributions, in the four particle event selection (p, $\pi^+$, $\pi^+$, $\pi^-$) to find cross sections of the different production channels, contributions of the intermediate resonances $\mathrm{\Delta^{++}}$ and $\mathrm{\Sigma(1385)^{+}}$ and corresponding angular distributions. A dominant resonant production is seen, where the reaction $\mathrm{\Lambda + \Delta^{++} + K^{0}}$ has an about ten times higher cross section ($\mathrm{29.45\pm0.08^{+1.67}_{-1.46}\pm2.06\,\mu b}$) than the analogous non-resonant reaction ($\mathrm{2.57\pm0.02^{+0.21}_{-1.98}\pm0.18\,\mu b}$). A similar result is obtained in the corresponding $\Sigma^{0}$ channels with $\mathrm{9.26\pm0.05^{+1.41}_{-0.31}\pm0.65\,\ mu b}$ in the resonant and $\mathrm{1.35\pm0.02^{+0.10}_{-1.35}\pm0.09\,\mu b}$ in the non-resonant reactions., Comment: 12 pages, 11 figures
Published: 2014
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35. Baryon resonance production and dielectron decays in proton-proton collisions at 3.5 GeV

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., König, I., König, W., Kolb, B. W., Kornakov, G., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Müntz, C., Naumann, L., Pachmayer, Y. C., Pałka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment, J.2
Abstract: We report on baryon resonance production and decay in proton-proton collisions at a kinetic energy of $3.5$ GeV based on data measured with HADES. The exclusive channels $pp \rightarrow np\pi^{+}$ and $pp \rightarrow pp\pi^{0}$ as well as $pp \rightarrow ppe^{+}e^{-}$ are studied simultaneously for the first time. The invariant masses and angular distributions of the pion-nucleon systems were studied and compared to simulations based on a resonance model ansatz assuming saturation of the pion production by an incoherent sum of baryonic resonances (R) with masses $<2~$ GeV/$c^2$. A very good description of the one-pion production is achieved allowing for an estimate of individual baryon-resonance production-cross-sections which are used as input to calculate the dielectron yields from $R\rightarrow pe^+e^-$ decays. Two models of the resonance decays into dielectrons are examined assuming a point-like $RN \gamma^*$ coupling and the dominance of the $\rho$ meson. The results of model calculations are compared to data from the exclusive $ppe^{+}e^{-}$ channel by means of the dielectron and $pe^+e^-$ invariant mass distributions., Comment: 17 pages, 14 figures
Published: 2014
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36. Searching a Dark Photon with HADES

Author: HADES Collaboration, Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Boehmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Goebel, K., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krasa, A., Krizek, F., Kruecken, R., Kuc, H., Kuehn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Muentz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Petousis, V., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wuestenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract: We present a search for the e+e- decay of a hypothetical dark photon, also names U vector boson, in inclusive dielectron spectra measured by HADES in the p (3.5 GeV) + p, Nb reactions, as well as the Ar (1.756 GeV/u) + KCl reaction. An upper limit on the kinetic mixing parameter squared epsilon^{2} at 90% CL has been obtained for the mass range M(U) = 0.02 - 0.55 GeV/c2 and is compared with the present world data set. For masses 0.03 - 0.1 GeV/c^2, the limit has been lowered with respect to previous results, allowing now to exclude a large part of the parameter region favoured by the muon g-2 anomaly. Furthermore, an improved upper limit on the branching ratio of 2.3 * 10^{-6} has been set on the helicity-suppressed direct decay of the eta meson, eta-> e+e-, at 90% CL.
Published: 2013

37. An upper limit on hypertriton production in collisions of Ar(1.76 AGeV)+KCl

Author: HADES Collaboration, Agakishiev, G., Belver, D., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Miche, J., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Rehnisch, L., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schmah, A., Schuldes, H., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spatarof, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: A high-statistic data sample of Ar(1.76 AGeV)+KCl events recorded with HADES is used to search for a hypertriton signal. An upper production limit per centrality-triggered event of $1.04$ x $10^{-3}$ on the $3\sigma$ level is derived. Comparing this value with the number of successfully reconstructed $\Lambda$ hyperons allows to determine an upper limit on the ratio $N_{_{\Lambda}^3H}/N_{\Lambda}$, which is confronted with statistical and coalescence-type model calculations.
Published: 2013

38. Inclusive pion and eta production in p+Nb collisions at 3.5 GeV beam energy

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Boehmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Goebel, K., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krasa, A., Krizek, F., Kruecken, R., Kuc, H., Kuehn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Muentz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wuestenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment
Abstract: Data on inclusive pion and eta production measured with the dielectron spectrometer HADES in the reaction p+93Nb at a kinetic beam energy of 3.5 GeV are presented. Our results, obtained with the photon conversion method, supplement the rather sparse information on neutral meson production in proton-nucleus reactions existing for this bombarding energy regime. The reconstructed e+e-e+e- transverse-momentum and rapidity distributions are confronted with transport model calculations, which account fairly well for both pi0 and eta production., Comment: 12 pages, 9 figures, submitted to Physical Review C
Published: 2013
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39. pK+\Lambda final state: towards the extraction of the ppK- contribution

Author: Fabbietti, L., Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Berger-Chen, J-C, Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Eberl, T., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krasa, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Lalik, R., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Moriniere, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, A. Solaguren-Beascoa Negre S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wüstenfel, J., Yurevich, S., and Zanevsky, Y. V.
Subjects: Nuclear Experiment
Abstract: The reaction p(@3.5\,GeV)+p -> p+\Lambda + K^+ can be studied to search for the existence of kaonic bound states like ppK^- leading to this final state. This effort has been motivated by the assumption that in p+p collisions the \Lambda(1405) resonance can act as a doorway to the formation of the kaonic bound states. The status of this analysis within the HADES collaboration, with particular emphasis on the comparison to simulations, is shown in this work and the deviation method utilized by the DISTO collaboration in a similar analysis is discussed. The outcome suggests the employment of a partial wave analysis to disentangle the different contributions to the measured pK^+\Lambda final state., Comment: 9 pages, 6 figures, proceeding of the HYP2012 conference Nucl. Phys. A (2013)
Published: 2013
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40. Baryonic resonances close to the Kbar-N threshold: the case of Lambda(1405) in pp collisions

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Müntz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfel, J., Yurevich, S., and Zanevsky, Y. V.
Subjects: Nuclear Experiment
Abstract: We present an analysis of the Lambda(1405) resonance produced in the reaction p+p->Sigma^{pm}+pi^{mp}+K+p at 3.5 GeV kinetic beam energy measured with HADES at GSI. The two charged decay channels Lambda(1405) -> Sigma^{\pm}+pi^{\mp} have been reconstructed for the first time in p+p collisions. The efficiency and acceptance-corrected spectral shapes show a peak position clearly below 1400 MeV/c^2. We find a total production cross section of sigma_{Lambda(1405)}=9.2 +- 0.9 +- 0.7 +3.3-1.0 mub. The analysis of its polar angle distribution suggests that the Lambda(1405) is produced isotropically in the p-p center of mass system., Comment: 5 pages 3 figures
Published: 2012
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41. First measurement of low momentum dielectrons radiated off cold nuclear matter

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kornakov, G., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Ladygin, V., Lalik, R., Lang, S., Lapidus, K., Lebedev, A., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Müntz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: We present data on dielectron emission in proton induced reactions on a Nb target at 3.5 GeV kinetic beam energy measured with HADES installed at GSI. The data represent the first high statistics measurement of proton-induced dielectron radiation from cold nuclear matter in a kinematic regime, where strong medium effects are expected. Combined with the good mass resolution of 2%, it is the first measurement sensitive to changes of the spectral functions of vector mesons, as predicted by models for hadrons at rest or small relative momenta. Comparing the e+e invariant mass spectra to elementary p+p data, we observe for e+e momenta Pee < 0.8 GeV/c a strong modification of the shape of the spectrum, which we attribute to an additional rho-like contribution and a decrease of omega yield. These opposite trends are tentatively interpreted as a strong coupling of the rho meson to baryonic resonances and an absorption of the omega meson, which are two aspects of in-medium modification of vector mesons.
Published: 2012
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42. Proceedings of the second International PrimeNet Workshop

Author: Adlarson, P., Amaryan, M., Bashkanov, M., Bergmann, F., Berłowski, M., Bijnens, J., Balkeståhl, L. Caldeira, Coderre, D., Czerwinski, E., Di Donato, C., Dybczak, A., Fariborz, A., Fröhlich, I., Goslawski, P., Gullström, C. -O., Gumberidze, M., Heijkenskjöld, L., Hodana, M., Hoferichter, M., Khan, F. A., Kolesár, M., Krzemien, W., Kubis, B., Kuc, H., Lanz, S., Lersch, D., Masjuan, P., Messchendorp, J., Metag, V., Niecknig, F., Nikolaev, A., Ozerianska, I., del Rio, E. Perez, Longhi, I. Prado, Gómez, À. Ramos, Ramalho, G., Redmer, C. F., Salabura, P., Sawant, S., Schneider, S., Skorodko, T., Stollenwerk, F., Terschlüsen, C., Thiel, A., Werthmüller, D., Wirzba, A., Wurm, P., Zdebik, J., and Zdráhal, M.
Subjects: Nuclear Experiment, Nuclear Theory
Abstract: These are the proceedings of the second PrimeNet Workshop, held in September 26-28, 2011, at the campus of Forschungszentrum J\"{u}lich, Germany. This workshop is part of the activities in the project "Study of Strongly Interacting Matter" (acronym HadronPhysics2), which is an integrating activity of the Seventh Framework Program of EU. This HP2 project contains several activities, one of them being the network PrimeNet having the focus on Meson Physics in Low-Energy QCD. This network is created to exchange information on experimental and theoretical ongoing activities on mainly eta and eta-prime physics at different European accelerator facilities and institutes., Comment: 149 pages, 47 contributions; Editors: D.Grzonka, B. H\"oistad, C. F. Redmer, S. Schadmand
Published: 2012

43. Inclusive dielectron production in proton-proton collisions at 2.2 GeV beam energy

Author: Agakishiev, G., Alvarez-Pol, H., Balanda, A., Bassini, R., Böhmer, M., Bokemeye, H., Boyard, J. L., Cabanelas, P., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O., Finocchiaro, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krizek, F., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lapidus, K., Liu, T., Maier, L., Markert, J., Metag, V., Michalska, B., Morinière, E., Mousa, J., Münch, M., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Pechenov, V., Pechenova, O., Cavalcanti, T. Perez, Pietraszko, J., Pospisil, V., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Sánchez, M., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Toia, A., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: Data on inclusive dielectron production are presented for the reaction p+p at 2.2 GeV measured with the High Acceptance DiElectron Spectrometer (HADES). Our results supplement data obtained earlier in this bombarding energy regime by DLS and HADES. The comparison with the 2.09 GeV DLS data is discussed. The reconstructed e+e- distributions are confronted with simulated pair cocktails, revealing an excess yield at invariant masses around 0.5 GeV/c2. Inclusive cross sections of neutral pion and eta production are obtained.
Published: 2012
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44. Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES

Author: HADES Collaboration, Agakishiev, G., Alvarez-Pol, H., Balanda, A., Bassini, R., Böhmer, M., Bokemeyer, H., Boyard, J. L., Cabanelas, P., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O., Finocchiaro, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krizek, F., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lapidus, K., Liu, T., Maier, L., Markert, J., Metag, V., Michalska, B., Morinière, E., Mousa, J., Münch, M., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Pechenov, V., Pechenova, O., Cavalcanti, T. Pérez, Pietraszko, J., Pospísil, V., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Sánchez, M., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Toia, A., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., and Zumbruch, P.
Subjects: Nuclear Experiment
Abstract: We present measurements of exclusive \pi^{+,0} and \eta\ production in pp reactions at 1.25 GeV and 2.2 GeV beam kinetic energy in hadron and dielectron channels. In the case of \pi^+ and \pi^0, high-statistics invariant-mass and angular distributions are obtained within the HADES acceptance as well as acceptance corrected distributions, which are compared to a resonance model. The sensitivity of the data to the yield and production angular distribution of \Delta(1232) and higher lying baryon resonances is shown, and an improved parameterization is proposed. The extracted cross sections are of special interest in the case of pp \to pp \eta, since controversial data exist at 2.0 GeV; we find \sigma =0.142 \pm 0.022 mb. Using the dielectron channels, the \pi^0 and \eta\ Dalitz decay signals are reconstructed with yields fully consistent with the hadronic channels. The electron invariant masses and acceptance corrected helicity angle distributions are found in good agreement with model predictions., Comment: 22 pages, 18 figures, to be published in EPJA
Published: 2012
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45. Production of Sigma{\pm}pi?pK+ in p+p reactions at 3.5 GeV beam energy

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Boehmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Destefanis, T. Christ M., Dohrmann, F., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., Gonza'lez-Di'az, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kr'asa, A., Krizek, F., Krücken, R., Kuc, H., Kuehn, W., Kugler, A., Kurepin, A., Lalik, R., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morinie're, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment
Abstract: We study the production of Sigma^+-pi^+-pK^+ particle quartets in p+p reactions at 3.5 GeV kinetic beam energy. The data were taken with the HADES experiment at GSI. This report evaluates the contribution of resonances like Lambda(1405$, Sigma(1385)^0, Lambda(1520), Delta(1232), N^* and K^*0 to the Sigma^+- pi^-+ p K+ final state. The resulting simulation model is compared to the experimental data in several angular distributions and it shows itself as suitable to evaluate the acceptance corrections properly., Comment: 15 pages, 5 figures
Published: 2012
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46. Determination of the $\mathbf{\Sigma(1385)^{0}/\Lambda(1405)}$ ratio in p+p collisions at 3.5 GeV

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chen, J. C., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Lalik, R., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y. V.
Subjects: Nuclear Experiment
Abstract: The aim of the present analysis is to determine the relative production cross sections of the $\Lambda$(1405) and $\Sigma(1385)^{0}$ resonances in p+p collisions at E$_{kin}$=3.5 GeV measured with HADES. Upper and lower limits have been determined for the ratio $\sigma_{(\Sigma(1385)^{0}+p+K^{+})}/\sigma_{(\Lambda(1405)+p+K^{+})}=0.76_{-0.26}^{+0.54}$. The knowledge of this ratio is an essential input for the analysis of the decay $\Lambda(1405)\rightarrow\Sigma^{\pm}\pi^{\mp}$, where an unambiguous separation of the $\Lambda$(1405) and $\Sigma(1385)^{0}$ signals is not possible.
Published: 2012
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47. Inclusive dielectron spectra in p+p collisions at 3.5 GeV

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chen, J. C., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Lalik, R., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment
Abstract: We present the inclusive invariant-mass, transverse momentum and rapidity distributions of dielectrons (e$^{+}$e$^{-}$ pairs) in p+p interactions at 3.5 GeV beam kinetic energy. In the vector-meson mass region, a distinct peak corresponding to direct $\omega$ decays is reconstructed with 2% mass resolution. The data is compared to predictions from three model calculations. Due to the large acceptance of the HADES apparatus for $e^{+}e^{-}$ invariant masses above 0.2 GeV/$c^{2}$ and for transverse pair momenta p$_{t}$ $ <$ 1 GeV/$c$, acceptance corrections are to a large extent model independent. This allows us to extract from dielectron data for the first time at this energy the inclusive production cross sections for light vector mesons. Inclusive production cross sections for $\pi^o$ and $\eta$ mesons are also reported. The obtained results will serve as an important reference for the study of vector meson production in proton-nucleus and heavy-ion collisions. Furthermore, using this data, an improved value for the upper bound of the branching ratio for direct $\eta$ decays into the electron-positron channel is obtained.
Published: 2011
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48. Baryonic resonances close to the Kbar-N threshold: the case of Sigma(1385)^+ in pp collisions

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., Boehmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chen, J. C., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Epple, E., Eberl, T., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krasa, A., Krizek, F., Kruecken, R., Kuc, H., Kuehn, W., Kugler, A., Kurepin, A., Lalik, R., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Moriniere, E., Mousa, J., Muentz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wuestenfeld, J., Yurevich, S., and Zanevsky, Y. V.
Subjects: Nuclear Experiment
Abstract: We present results of an exclusive measurement of the first excited state of the Sigma hyperon, Sigma(1385)^+, produced in p+p -> Sigma^+ + K^+ + n at 3.5 GeV beam energy. The extracted data allow to study in detail the invariant mass distribution of the Sigma(1385)^+. The mass distribution is well described by a relativistic Breit-Wigner function with a maximum at m_0 = 1383.2 +- 0.9 MeV/c^2 and a width of 40.2 +- 2.1 MeV/c^2. The exclusive production cross-section comes out to be 22.27 +- 0.89 +- 1.56 +3.07 -2.10 mu b. Angular distributions of the Sigma(1385)^+ in different reference frames are found to be compatible with the hypothesis that 33 % of Sigma(1385)^+ result from the decay of an intermediate Delta^{++} resonance., Comment: 12 pages; 12 figures; submitted to PRC
Published: 2011
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49. Dielectron production in Ar+KCl collisions at 1.76A GeV

Author: Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Eberl, T., Epple, E., Fabbbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., Gonzalez-Díaz, D., Guber, F., Gumberidze, M., Heinz, T., Hennino, T., Holzmann, R., Huck, P., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krasa, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Liu, K. Lapidus T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Moriniere, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment
Abstract: We present results on dielectron production in Ar+KCl collisions at 1.76A GeV. For the first time $\omega$ mesons could be reconstructed in a heavy-ion reaction at a bombarding energy which is well below the production threshold in free nucleon-nucleon collisions. The omega multiplicity has been extracted and compared to the yields of other particles, in particular of the phi meson. At intermediate e+e- invariant masses, we find a strong enhancement of the pair yield over a reference spectrum from elementary nucleon-nucleon reactions suggesting the onset of non-trivial effects of the nuclear medium. Transverse-mass spectra and angular distributions have been reconstructed in three invariant mass bins. In the former unexpectedly large slopes are found for high-mass pairs. The latter, in particular the helicity-angle distributions, are largely consistent with expectations for a pair cocktail dominated at intermediate masses by delta Dalitz decays., Comment: 16 pages, 14 figures, accepted for publication by Phys. Rev. C
Published: 2011
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50. Single and double pion production in np collisions at 1.25 GeV with HADES

Author: The HADES Collaboration, Kurilkin, A. K., Agakishiev, G., Balanda, A., Belver, D., Belyaev, A., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Díaz, J., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gil, A., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., Huck, P., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kopp, A., Korcyl, G., Kornakov, GK., Kotte, R., Kozuch, A., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Kurilkin, P., Khlitz, P., Ladygin, V., Lamas-Valverde, J., Lang, S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Müntz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roskoss, J., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Siebenson, J., Sobolev, Yu. G., Spataro, S., Ströbele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Vasiliev, T., Wagner, V., Weber, M., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.
Subjects: Nuclear Experiment
Abstract: The preliminary results on charged pion production in np collisions at an incident beam energy of 1.25 GeV measured with HADES are presented. The np reactions were isolated in dp collisions at 1.25 GeV/u using the Forward Wall hodoscope, which allowed to register spectator protons. The results for np -> pppi-, np -> nppi+pi- and np -> dpi+pi- channels are compared with OPE calculations. A reasonable agreement between experimental results and the predictions of the OPE+OBE model is observed., Comment: 6 pages, 6 figures, conference proceeding: The XX International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics", JINR, Dubna, Russia, October 4-9, 2010
Published: 2011

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