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117 results on '"Trebacz, R."'

1. 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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2. 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

3. 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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4. 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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5. 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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6. 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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7. 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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8. 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

9. 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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10. 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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11. 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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12. 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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13. 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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14. 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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15. 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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16. 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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17. 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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18. 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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19. 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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20. 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

21. Cross section in deuteron-proton elastic scattering at 1.25 GeV/u

Author

HADES Collaboration, Kurilkin, P. 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, G. K., Kotte, R., Kozuch, A., Krása, A., Krizek, F., Krücken, R., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Kurilkin, A., 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

First results of the differential cross section in dp elastic scattering at 1.25 GeV/u measured with the HADES over a large angular range are reported. The obtained data corresponds to large transverse momenta, where a high sensitivity to the two-nucleon and three-nucleon short-range correlations is expected., Comment: Talk given at the XX-th International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics", JINR, Dubna, Russia, October 4-9, 2010

Published
2011

22. Hyperon production in Ar+KCl collisions at 1.76A GeV

Author

Agakishiev, G., Balanda, A., Bannier, B., Bassini, R., Belver, D., Belyaev, A., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heilmann, M., Heinz, T., Hennino, T., Holzmann, R., Huck, P., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Kruecken, R., Kuehn, 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., Michel, J., Mishra, D., Moriniere, E., Mousa, J., Muentz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Perez-Cavalcanti, T., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., 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., Wisniowski, M., Wojcik, T., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., Zumbruch, P., and Collaboration, HADES

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

We present transverse momentum spectra, rapidity distribution and multiplicity of Lambda-hyperons measured with the HADES spectrometer in the reaction Ar(1.76A GeV)+KCl. The yield of Xi- is calculated from our previously reported Xi-/(Lambda+Sigma0) ratio and compared to other strange particle multiplicities. Employing a strangeness balance equation the multiplicities of the yet unmeasured charged Sigma hyperons can be estimated. Finally a statistical hadronization model is used to fit the yields of pi-, K+, K0s, K-, phi, Lambda and Xi-. The resulting chemical freeze-out temperature of T=(76+-2) MeV is compared to the measured slope parameters obtained from fits to the transverse mass distributions of the particles.

Published
2010
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23. Lambda-p femtoscopy in collisions of Ar+KCl at 1.76 AGeV

Author

Agakishiev, G., Balanda, A., Bassini, R., 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., Eberl, T., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., 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., Michel, J., Mishra, D., 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., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

Results on $\Lambda$p femtoscopy are reported at the lowest energy so far. At a beam energy of 1.76A~GeV, the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity $\Lambda$ sample was collected, allowing for the investigation of $\Lambda$ p correlations at small relative momenta. The experimental correlation function is compared to corresponding model calculations allowing the determination of the space-time extent of the $\Lambda$p emission source. The $\Lambda$p source radius is found slightly smaller than the pp correlation radius for a similar collis ion system. The present $\Lambda$p radius is significantly smaller than that found for Au+Au/Pb+Pb collisio ns in the AGS, SPS and RHIC energy domains, but larger than that observed for electroproduction from He. Taking into account all available data, we find the $\Lambda$p source radius to increase almost linearly with the number of participants to the power of one-third., Comment: 5 pages, 3 figures, submitted to Phys. Rev. C

Published
2010
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24. Recent results from HADES on electron pair production in relativistic heavy-ion collisions

Author

The HADES Collaboration, Galatyuk, T., 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., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., 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., 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., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., and Zhou, P.

Subjects
Nuclear Experiment
Abstract

Systematic investigations of dilepton production are performed at the SIS accelerator of GSI with the HADES spectrometer. The goal of this program is a detailed understanding of di-electron emission from hadronic systems at moderate temperatures and densities. New results obtained in HADES experiments focussing on electron pair production in elementary collisions are reported here. They pave the way to a better understanding of the origin of the so-called excess pairs earlier on observed in heavy-ion collisions by the DLS collaboration and lately confirmed in two measurements of the HADES collaboration using C+C and Ar+KCl collisions. Results of these studies are discussed., Comment: 8 pages, 5 figures, To appear in the proceedings of 5th International Workshop on Critical Point and Onset of Deconfinement (CPOD), Brookhaven, Upton, New York, 8-12 Jun 2009

Published
2009

25. Origin of the low-mass electron pair excess in light nucleus-nucleus collisions

Author

The HADES Collaboration, 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., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., 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., 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., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., and Zhou, P.

Subjects
Nuclear Experiment
Abstract

We report measurements of electron pair production in elementary p+p and d+p reactions at 1.25 GeV/u with the HADES spectrometer. For the first time, the electron pairs were reconstructed for n+p reactions by detecting the proton spectator from the deuteron breakup. We find that the yield of electron pairs with invariant mass Me+e- > 0.15 GeV/c2 is about an order of magnitude larger in n+p reactions as compared to p+p. A comparison to model calculations demonstrates that the production mechanism is not sufficiently described yet. The electron pair spectra measured in C+C reactions are compatible with a superposition of elementary n+p and p+p collisions, leaving little room for additional electron pair sources in such light collision systems., Comment: 11 pages, 2 figures, \usepackage{epsfig}

Published
2009
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26. A versatile method for simulating pp -> ppe+e- and dp -> pne+e-p_spec reactions

Author

Froehlich, I., Dohrmann, F., Galatyuk, T., Holzmann, R., Kaehlitz, P. K., Kaempfer, B., Moriniere, E., Pachmayer, Y. C., Ramstein, B., Salabura, P., Stroth, J., Trebacz, R., Van de Wiele, J., and Wuestenfeld, J.

Subjects
Nuclear Experiment
Abstract

We have developed a versatile software package for the simulation of di-electron production in $pp$ and $dp$ collisions at SIS energies. Particular attention has been paid to incorporate different descriptions of the Dalitz decay $\Delta \to N e^+e^-$ via a common interface. In addition, suitable parameterizations for the virtual bremsstrahlung process $NN \to NN e^+e^-$ based on one-boson exchange models have been implemented. Such simulation tools with high flexibility of the framework are important for the interpretation of the di-electron data taken with the HADES spectrometer and the design of forthcoming experiments.

Published
2009
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27. Inclusive Dielectron Production in Ar+KCl Collisions at 1.76 AGeV studied with HADES

Author

The HADES Collaboration, Krizek, F., Agakishiev, G., Balanda, A., Bellia, G., Belver, D., Belyaev, A., Blanco, A., Boehmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Grosse, E., Guber, F., Heilmann, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krasa, A., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Lamas-Valverde, J., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Marin, J., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Moriniere, E., Mousa, J., Muentz, C., Naumann, L., Novotny, R., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Cavalcanti, T. Perez, Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Simon, R., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Veretenkin, I., Wagner, V., Weber, M., Wisniowski, M., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

Results of the HADES measurement of inclusive dielectron production in Ar+KCl collisions at a kinetic beam energy of 1.76 AGeV are presented. For the first time, high mass resolution spectroscopy was performed. The invariant mass spectrum of dielectrons is compared with predictions of UrQMD and HSD transport codes., Comment: 4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee

Published
2009
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28. Deep sub-threshold $\Xi^-$ production in Ar+KCl reactions at 1.76A GeV

Author

Agakishiev, G., Balanda, A., Bassini, R., 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., Eberl, T., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., 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., Michel, J., Mishra, D., 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., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., and Zhou, P.

Subjects
Nuclear Experiment
Abstract

We report first results on a deep sub-threshold production of the doubly strange hyperon $\Xi^-$ in a heavy-ion reaction. At a beam energy of 1.76A GeV the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity $\Lambda$ sample was collected, allowing for the investigation of the decay channel $\Xi^- \to \Lambda \pi^-$. The deduced $\Xi^-/(\Lambda+\Sigma^0)$ production ratio of $(5.6 \pm 1.2 ^{+1.8}_{-1.7})\cdot 10^{-3}$ is significantly larger than available model predictions., Comment: 4 pages, including 4 figures

Published
2009
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29. Charged pion production in C+C and Ar+KCl collisions measured with HADES

Author

The HADES Collaboration, Tlusty, P., Agakishiev, G., Balanda, A., Bellia, G., Belver, D., Belyaev, A., Blanco, A., Boehmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Grosse, E., Guber, F., Heilmann, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krasa, A., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Lamas-Valverde, J., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Marin, J., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Moriniere, E., Mousa, J., Muentz, C., Naumann, L., Novotny, R., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Cavalcanti, T. Perez, Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Simon, R., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Traxler, M., Trebacz, R., Tsertos, H., Veretenkin, I., Wagner, V., Weber, M., Wisniowski, M., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

Results of a study of charged pion production in 12C+12C collisions at incident beam energies of 1A GeV and 2A GeV, and 40Ar+natKCl at 1.76AGeV, using the spectrometer HADES at GSI, are presented. We have performed a measurement of the transverse momentum distributions of pi+- mesons covering a fairly large rapidity interval, in case of the C+C collision system for the first time. The yields, transverse mass and angular distributions are compared with a transport model as well as with existing data from other experiments., Comment: 7 pages, 2 figures Contribution presented at the XLVII International Winter Meeting on Nuclear Physics, Bormio (Italy), Jan. 26-30, 2009

Published
2009

30. Future perspectives at SIS-100 with HADES-at-FAIR

Author

The HADES Collaboration, Froehlich, I., Agakishiev, G., Balanda, A., Bellia, G., Belver, D., Belyaev, A., Blanco, A., Boehmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Grosse, E., Guber, F., Heilmann, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krasa, A., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Lamas-Valverde, J., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Marin, J., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Moriniere, E., Mousa, J., Muentz, C., Naumann, L., Novotny, R., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Cavalcanti, T. Perez, Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Simon, R., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Veretenkin, I., Wagner, V., Weber, M., Wisniowski, M., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

Currently, the HADES spectrometer undergoes un upgrade program to be prepared for measurements at the upcoming SIS-100 synchrotron at FAIR. We describe the current status of the HADES di-electron measurements at the SIS-18 and our future plans for SIS-100., Comment: Invited contribution presented at the XLVII International Winter Meeting on Nuclear Physics, Bormio (Italy), Jan. 26-30, 2009

Published
2009

31. Measurement of charged pions in 12C + 12C collisions at 1A GeV and 2A GeV with HADES

Author

The HADES Collaboration, Agakishiev, G., Agodi, C., Balanda, A., Bellia, G., Belver, D., Belyaev, A., Bielcik, J., Blanco, A., Bortolotti, A., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Chernenko, S., Christ, T., Coniglione, R., Destefanis, M., Diaz, J., Dohrmann, F., Duran, I., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O., Ferreira-Marques, R., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Grosse, E., Guber, F., Heilmann, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krasa, A., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Lamas-Valverde, J., Lang, S., Lange, J. S., Lapidus, K., Lopes, L., Lorenz, M., Maier, L., Maiolino, C., Mangiarotti, A., Marin, J., Markert, J., Metag, V., Michalska, B., Michel, J., Moriniere, E., Mousa, J., Muench, M., Muentz, C., Naumann, L., Novotny, R., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Cavalcanti, T. Perez, Piattelli, P., Pietraszko, J., Pospisil, V., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Sapienza, P., Schmah, A., Schroeder, C., Schwab, E., Simon, R. S., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

We present the results of a study of charged pion production in 12C + 12C collisions at incident beam energies of 1A GeV and 2A GeV using the HADES spectrometer at GSI. The main emphasis of the HADES program is on the dielectron signal from the early phase of the collision. Here, however, we discuss the data with respect to the emission of charged hadrons, specifically the production of pi+- mesons, which are related to neutral pions representing a dominant contribution to the dielectron yield. We have performed the first large-angular range measurement of the distribution of pi+- mesons for the 12C + 12C collision system covering a fairly large rapidity interval. The pion yields, transverse-mass and angular distributions are compared with calculations done within a transport model, as well as with existing data from other experiments. The anisotropy of pion production is systematically analyzed., Comment: 15 pages, 13 figures, v2 - the text unchanged, only full author list added to METADATA (in v1 only the first author and collaboration name), reference to published paper added

Published
2009
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32. The TRB for HADES and FAIR experiments at GSI

Author

Krzemien, W., Frohlich, I., Kajetanowicz, M., Korcyl, K., Michel, J., Palka, M., Salabura, P., Schrader, C., Skott, P., Strobele, H., Stroth, J., Tarantola, A., Traxler, M., and Trebacz, R.

Subjects
Nuclear Experiment
Abstract

The TRB hardware module is a multi-purpose Trigger and Readout Board with on-board DAQ functionality developed for the upgrade of the HADES experiment. It contains a single computer chip (Etrax) running Linux as a well as a 100 Mbit/s Ethernet interface. It has been orginally designed to work as a 128-channel Time to Digital Converter based on the HPTDC chip from CERN. The new version contains a 2 Gbit/s optical link and an interface connector (15 Gbit/s) in order to realize an add-on card concept which makes the hardware very flexible. Moreover, an FPGA chip (Xilinx, Virtex 4 LX 40) and a TigerSharc DSP provide new computing resources which can be used to run on-line analysis algorithms. The TRB is proposed as a prototype for new modules for the planned detector systems PANDA and CBM at the future FAIR facility at GSI-Darmstadt., Comment: Presented at 10th ICATPP Conference on Astroparticle, Particle and Space Physics, Detectors and Medical Physics Applications, Villa Olmo, Como, 8-12 October 2007 5 pages, 2 figures

Published
2008

33. Study of dielectron production in C+C collisions at 1 AGeV

Author

HADES Collaboration, Agakishiev, G., Agodi, C., Pol, H. Alvarez, Balanda, A., Bassini, R., Bellia, G., Belver, D., Belyaev, A., Blanco, A., Boehmer, M., Bortolotti, A., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Diaz, D. Gonzalez, Grosse, E., Guber, F., Heilmann, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krasa, A., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Valverde, J. Lamas, Lang, S., Lange, J. S., Lapidus, K., Lopes, L., Maier, L., Mangiarotti, A., Marin, J., Markert, J., Metag, V., Michalska, B., Mishra, D., Moriniere, E., Mousa, J., Muench, M., Muentz, C., Naumann, L., Novotny, R., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Perez, T., Pietraszko, J., Pleskac, R., Przygoda, W., Ramstein, B., Reshetin, A., Stephan, M. Roy, Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Simon, R., Sobolev, Y., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Toia, A., Traxler, M., Trebacz, R., Tsertos, H., Veretenkin, I., Wagner, V., Weber, M., Wen, H., Wisniowski, M., Wojcik, T., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

The emission of e+e- pairs from C+C collisions at an incident energy of 1 GeV per nucleon has been investigated. The measured production probabilities, spanning from the pi0-Dalitz to the rho/omega! invariant-mass region, display a strong excess above the cocktail of standard hadronic sources. The bombarding-energy dependence of this excess is found to scale like pion production, rather than like eta production. The data are in good agreement with results obtained in the former DLS experiment., Comment: submitted to Physics Letters B

Published
2007
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34. Study of the quasi-free np→npπ+π− 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 and High Energy Physics, Np collisions, Resonance excitations, Two-pion production, Nuclear Theory, np collisions, Nuclear Experiment, lcsh:Physics, lcsh:QC1-999
Abstract

The tagged quasi-free np→npπ+π− 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 ( s∼2.42 GeV/c for the quasi-free collision). For the first time, differential distributions of solid statistics for π+π− 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→npπ+π− reaction are compared with different models. This comparison confirms the dominance of the t -channel with ΔΔ 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 π+π− 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∼2.38 GeV and with width Γ∼70 MeV .

Published
2015

35. Statistical hadronization model analysis of hadron yields in p + Nb and Ar + KCl at SIS18 energies

Author

Krücken, R., HADES Collaboration, Agakishiev, G., Arnold, O., Bałanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, Pablo, 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., 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, Antonín, Krizek, F., 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., Mihaylov, D., Michel, J., Morinière, E., Mousa, J., Müntz, C., Münzer, R., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Yiannis, 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, Y. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, Haralambos, Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wirth, J., Wisniowski, M., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), HADES, and Tsertos, Haralambos [0000-0001-5966-343X]

Subjects
Physics, Nuclear reaction, Particle physics, Nuclear and High Energy Physics, Meson, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, Branching fraction, Hadron, Hyperon, Elementary particle, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Hadronization, Nuclear physics, Baryon, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], 010306 general physics, Nuclear Experiment
Abstract

The HADES data from p + Nb collisions at a center-of-mass energy of √sNN = 3.2 GeV are analyzed employing a statistical hadronization model. The model can successfully describe the production yields of the identified hadrons π0, η, Ʌ, K0 s, ω with parameters Tchem = (99 ± 11) MeV and μb = (619 ± 34) MeV, which fit well into the chemical freeze-out systematics found in heavy-ion collisions. In addition, we reanalyze our previous HADES data from Ar + KCl collisions at √SNN = 2.6 GeV with an updated version of the 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 as a function of colliding energy and system size. Despite its success, the model fails to describe the observed Ξ- yields in both, p + Nb and Ar + KCl. Special emphasis is put on feed-down contributions from higher-lying resonance states as a possible explanation for the observed excess. © 2016, SIF, Springer-Verlag Berlin Heidelberg. 52 6 Cited By :6

Published
2016
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36. Statistical Hadronization Model analysis of hadron yields in p+Nb and Ar+KCl at SIS18 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., Mihaylov, D., 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, Y. 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., Wirth, J., Wisniowski, M., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.

Subjects
Nuclear Experiment
Abstract

The HADES data from p+Nb collisions at a center of mass energy of sqrt(sNN)= 3.2 GeV are analyzed employing a statistical hadronization model. The model can successfully describe the production yields of the identified hadrons π0, η, Λ, K0s, ω with parameters Tchem = (99+-11) MeV and μb = (619+-34) MeV, which fits well into the chemical freeze-out systematics found in heavy-ion collisions. In addition, we reanalyze our previous HADES data from Ar+KCl collisions at sqrt(sNN= 2.6 GeV with an updated version of the 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. Despite this success, the model fails to describe the observed Ξ- yields in both, p+Nb and Ar+KCl. Special emphasis is put on feed-down contributions from higher-lying resonance states as a possible explanation for the observed excess.

Published
2016

37. DILEPTON PRODUCTION STUDIED WITH THE HADES SPECTROMETER

Author

Krücken, R., Rustamov, A., Agakishiev, G., Bałanda, A., Belver, D., Belyaev, A., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, Pablo, Castro, E., Chernenko, S., Diáz, 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., Gumberidze, M., 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, G. K., Kotte, R., Kozuch, A., Krása, Antonín, Krizek, F., Kuc, H., Kühn, W., Kugler, A., Kurepin, A., Kurilkin, A., Kurilkin, P., Kählitz, 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, Yiannis, Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roskoss, J., Sadovsky, A., Salabura, P., Schmah, A., Siebenson, J., Sobolev, Yu G., Spataro, S., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, Haralambos, Vasiliev, T., Wagner, V., Weber, M., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., Tsertos, Haralambos [0000-0001-5966-343X], Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and HADES

Subjects
Nuclear and High Energy Physics, Meson, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Kinetic energy, 01 natural sciences, 7. Clean energy, Spectral line, Nuclear physics, Pion, Phase (matter), 0103 physical sciences, Dilepton spectroscopy, meson production, nucleus-nucleus collisions, Nuclear Experiment, 010306 general physics, Physics, Spectrometer, 010308 nuclear & particles physics, Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Yield (chemistry), Atomic physics, Ground state
Abstract

With the HADES spectrometer at GSI we have studied dilepton production in various collision systems from elementary N + N , over p + A , up to the medium-heavy Ar + KCl system. We have confirmed the puzzling results of the former DLS collaboration at the Bevalac. While we have traced the origin of the excess pair yield in C + C collisions to elementary p + p and n + p processes, we find a significant contribution from the dense phase of the collision in larger Ar + KCl system. From recently obtained e + e - pair spectra in p + p and p + Nb interactions at 3.5 GeV kinetic beam energy the inclusive production cross sections for neutral pions, η , ω and ρ mesons are extracted for the first time at this beam energy. Furthermore, the production mechanisms of the vector mesons, which are not known at these energies, are investigated. The direct comparison of p + p and p + Nb data allows us to investigate in-medium mass modifications of vector mesons at nuclear ground state density. On the other hand, exclusive production of ω and η mesons in p + p reactions at 3.5 GeV were studied via their π+π-π0 decay channel. Production cross sections and angular distributions for both states were determined.

Published
2011
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38. Study of the quasi-free $np \to np ��^+��^-$ reaction with a deuterium beam at 1.25 GeV/nucleon

Author

Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., B��hmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., D��az, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fr��hlich, I., Galatyuk, T., Garz��n, J. A., Gernh��user, R., Gil, A., Gilardi, C., G��bel, K., Golubeva, M., Gonz��lez-D��az, D., Guber, F., Gumberidze, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., K��mpfer, B., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Kr��cken, R., K��hn, 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., Morini��re, E., Mousa, J., M��ntz, 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., Str��bele, 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., W��stenfeld, J., Yurevich, S., Zanevsky, Y., and Zhou, P.

Subjects
Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The tagged quasi-free $np \to np��^+��^-$ 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 $��^{+}��^{-}$ 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 $np\rightarrow np��^{+}��^{-}$ reaction are compared with different models. This comparison confirms the dominance of the $t$-channel with $����$ 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 $��^{+}��^{-}$ 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 $��\sim$ 70 MeV.

Published
2015
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39. Partial Wave Analysis of the Reaction p(3.5GeV)+p→pK+Λ to Search for the 'ppK−' Bound State

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., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., Zanevsky, Y.V., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and HADES

Subjects
Nuclear and High Energy Physics, interference: effect, 3.5 GeV-kin, mass [cluster], p p: exclusive reaction, QC1-999, cluster: mass, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Lambda: associated production, Low energy QCD, effect [interference], K+: hadroproduction, +Lambda+p+K%2B%22">p p --> Lambda p K+, p p K −, Kaonic nuclei, ddc:530, angular distribution, cross section: upper limit, Nuclear Experiment, Darmstadt SIS, exclusive reaction [p p], (2nucleon anti-K) [bound state], Anti-kaon-nucleon physics, Partial wave analysis, PpK, associated production [Lambda], Anti-kaon–nucleon physics, Physics, partial wave analysis, hadroproduction [K+], ddc, mass spectrum: two-particle, resonance, HADES, bound state: (2nucleon anti-K), two-particle [mass spectrum], ppK−, upper limit [cross section], experimental results
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
2015
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40. 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. 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, Y. 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 Theory, High Energy Physics::Experiment, Nuclear Experiment
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 (nπ+ and pπ0) 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 Δ(1232), yet with a sizable impact of the N(1440) and non-resonant partial waves. The obtained resonance production cross sections provide a useful normalization for the further analysis of the Δ+ -> pe+e- Dalitz decay.

Published
2015

41. 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., 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., Müntzer, 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. V., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and HADES

Subjects
FOS: Physical sciences, High Energy Physics::Experiment, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment (nucl-ex), 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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42. Searching a Dark Photon with HADES

Author

Krücken, R., Agakishiev, G., Bałanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, Pablo, 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, Antonín, Krizek, F., 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, Yiannis, Pechenov, V., Pechenova, O., Petousis, Vlassis, 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, Y., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, Haralambos, Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), HADES, and Tsertos, Haralambos [0000-0001-5966-343X]

Subjects
Nuclear and High Energy Physics, Particle physics, Rare eta decays, Meson, PHI-MESON DECAYS, Dark matter, FOS: Physical sciences, dark matter, Dark photon, Spectral line, High Energy Physics - Experiment, Standard Model, Vector boson, Nuclear physics, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), VECTOR GAUGE BOSON, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], ddc:530, Nuclear Experiment, Physics, Muon, Branching fraction, Hidden sector, hidden sector, rare eta decays, High Energy Physics - Phenomenology, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], dark photon, High Energy Physics::Experiment
Abstract

Physics letters / B 731, 265 - 271 (2014). doi:10.1016/j.physletb.2014.02.035, Published by North-Holland Publ., Amsterdam

Published
2014
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43. Baryon resonance production and dielectron decays in proton-proton collisions at 3.5 GeV

Author

Krücken, R., Agakishiev, G., Bałanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, Pablo, Chernenko, S., Dybczak, A., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garźon, J. A., Gernhäuser, R., Göbel, K., Golubeva, M., Gonźalez-D́iaz, 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, Antonín, Krizek, F., 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., Mangiarott, A., Markert, J., Metag, V., Michalska, B., Miche, J., M̈untz, C., Naumann, L., Pachmayer, Y. C., Palka, M., Parpottas, Yiannis, 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, Y. G., Spataroh, S., Spruck, B., Str̈obele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, Haralambos, Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Ẅustenfeld, J., Yurevich, S., Zanevsky, Y., and Tsertos, Haralambos [0000-0001-5966-343X]

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, J.2, Meson, Nuclear Theory, FOS: Physical sciences, Resonance, Invariant (physics), Kinetic energy, nucl-ex, 7. Clean energy, 3. Good health, Baryon, Pion, TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY, Invariant mass, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment, Ansatz
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 $, Comment: 17 pages, 14 figures

Published
2014

44. Medium effects in proton-induced K0 production at 3.5 GeV

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., Göbe, 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, Y. 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. V., Gaitanos, T., and Weil, J.

Subjects
Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract

We present the analysis of the inclusive K0 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 support 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 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 experimental results from p+Nb collisions to the in-medium kaon potential.

Published
2014

45. 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., Zanevsky, Y., Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and HADES

Subjects
Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment (nucl-ex), 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., 12 pages, 9 figures, submitted to Physical Review C

Published
2013
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46. Deep sub-threshold K*(892)0 production in collisions of Ar + KCl at 1.76A GeV

Author

Krücken, R., Agakishiev, G., Bałanda, A., Bassini, R., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, Pablo, Castro, E., Chernenko, S., Christ, T., Destefanis, M., Diáz, J., Dohrmann, F., Dybczak, A., Eberl, T., Epple, E., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Heilmann, M., Heinz, T., Hennino, T., Holzmann, R., Huck, P., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., 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., Michel, J., Mishra, D., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Yiannis, Pechenov, V., Pechenova, O., Pérez Cavalcanti, T., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Y. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, Haralambos, Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., Zumbruch, P., and Tsertos, Haralambos [0000-0001-5966-343X]

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Meson, 010308 nuclear & particles physics, Branching fraction, Hadron, 7. Clean energy, 01 natural sciences, Hadronization, Nuclear physics, 0103 physical sciences, Production (computer science), Atomic physics, 010306 general physics, Nuclear Experiment, Energy (signal processing), Dimensionless quantity
Abstract

Results on the deep sub-threshold production of the short-lived hadronic resonance K*(892)0 are reported for collisions of Ar + KCl at 1.76A GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. The K*(892)0 production probability per central collision of \( P_{K^{*0}}=(4.4\pm 1.1 \pm 0.5)\times 10^{-4}\) and the K*(892)0/K0 ratio of \( P_{K^{*0}}/P_{K^0}=(1.9\pm 0.5\pm 0.3)\times 10^{-2}\) are determined at the lowest energy so far (i.e. deep below the threshold for the corresponding production in nucleon-nucleon collisions, \( \sqrt{s_{NN}}-\sqrt{s_{thr}}=-340\) MeV). The K*0/K0 ratio is compared with results of other experiments and with the predictions of the UrQMD transport approach and of the statistical hadronization model. The experimental K*0 yield and the K*0/K0 ratio are overestimated by the transport model by factors of about five and two, respectively. In a chemically equilibrated medium the ratio corresponds to a temperature of the thermalized system being systematically lower than the value determined by the yields of the stable and long-lived hadrons produced in Ar + KCl collisions. From the present measurement, we conclude that sub-threshold K* production either cannot be considered to proceed in a system being in thermal equilibrium or these short-lived resonances appear undersaturated, for example as a result of the rescattering of the decay particles in the ambient hadronic medium.

Published
2013

47. Inclusive pion and η production in p+Nb collisions at 3.5 GeV beam energy

Author

Krücken, R., Agakishiev, G., Bałanda, A., Belver, D., Belyaev, A., Berger-Chen, J. C., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, Pablo, 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, Antonín, Krizek, F., 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, Yiannis, 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, Y. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, Haralambos, Vasiliev, T., Wagner, V., Weber, M., Wendisch, C., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., and Tsertos, Haralambos [0000-0001-5966-343X]

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Data on inclusive pion and η 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 π0 and η production. © 2013 American Physical Society. 88 2 Cited By :8

Published
2013

48. Hades experiments: investigation of hadron in-medium properties

Author

Agakishiev, G., Behnke, C., Belver, D., Belyaev, A., 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., Fabbietti, L., Fateev, O., 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., Ierusalimov, A., 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, Y. 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
High Energy Physics::Phenomenology, Nuclear Theory, Nuclear Experiment
Abstract

Hadron modications in nuclear matter are discussed in connection to chiral symmetry restoration and/or hadronic many body eects. Experiments with photon, proton and heavy ion beams are used to probe properties of hadrons embedded in nuclear matter at different temperatures and densities. Most of the information has been gathered for the light vector mesons ρ, ω and φ. HADES is a second generation experiment operating at GSI with the main aim to study in-medium mass modication by means of dielectron production at SIS18/Bevelac energy range. Large acceptance and excellent particle identication capabilities allows also for measurement of strangeness production. These abilities combined with the variety of beams provided by the SIS18 allows for characterization of properties of the dense baryonic matter properties created in heavy ion collisions at these energies. A review of recent experimental results obtained by HADES is presented, with main emphasis on hadron properties in nuclear matter.

Published
2013

49. Proton induced dielectron radiation off Nb: Pt and Y distributions

Author

Lorenz, M., Weber, M., Agakishiev, G., Behnke, C., Belver, D., Belyaev, A., 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., Fabbietti, L., Fateev, O., 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., Ierusalimov, A., 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., 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, Y. 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., Wendisch, C., Wüstenfeld, J., Yurevich, S., and Zanevsky, Y.

Subjects
Nuclear Experiment
Abstract

Following our recent letter [1] on inclusive e+e− pair production in proton induced reactions at Ekin = 3.5 GeV on the nucleus Nb, we present here in addition the transverse and rapidity distributions for various e+e− invariant mass bins and compare them to reference data measured in p+p reactions.

Published
2013

50. 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

Agakishiev, G., Alvarez-Poll, H., Bałanda, A., Bassini, R., Böhmer, M., Bokemeyer, H., Boyard, J. L., Cabanelas, Pablo, 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-Diaz, 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., Pérez Cavalcanti, T., 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, Y. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Toia, A., Traxler, M., Trebacz, R., Tsertos, Haralambos, Wagner, V., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., Zumbruch, P., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), HADES, and Tsertos, Haralambos [0000-0001-5966-343X]

Subjects
Nuclear and High Energy Physics, MESON PRODUCTION, SINGLE-PION, Hadron, SIS ENERGIES, FOS: Physical sciences, Electron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Kinetic energy, 01 natural sciences, Nuclear physics, Pion, 0103 physical sciences, SCATTERING, ddc:530, NEAR-THRESHOLD, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Physics, NUCLEON-NUCLEON COLLISIONS, 010308 nuclear & particles physics, Resonance, Sigma, OF-FLIGHT SPECTROMETER, Helicity, Baryon, proton-proton collisions, High Energy Physics::Experiment, TOTAL CROSS-SECTIONS, INTERMEDIATE ENERGIES
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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