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1. Differential Cross Sections for Neutron-Proton Scattering in the Region of the $d^*(2380)$ Dibaryon Resonance

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. --O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hodana, M., Höistad, B., Hüsken, N., Jany, A., Jany, B. R., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zink, A., Złomańczuk, J., {Ż}uprański, P., {Ż}urek, M., Workman, R. L., Briscoe, W. J., Strakovsky, I. I., and Švarc, A.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: Differential cross sections have been extracted from exclusive and kinematically complete high-statistics measurements of quasifree polarized $\vec{n}p$ scattering performed in the energy region of the $d^*(2380)$ dibaryon resonance covering the the range of beam energies $T_n$ = 0.98 - 1.29 GeV ($\sqrt s$ = 2.32 - 2.44 GeV). The experiment was carried out with the WASA-at-COSY setup having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process $dp \to np + p_{spectator}$. That way the $np$ differential cross section $\sigma(\Theta)$ was measured over a large angular range. The obtained angular distributions complement the corresponding analyzing power $A_y(\Theta)$ measurements published previously. A SAID partial-wave analysis incorporating the new data strengthens the finding of a resonance pole in the coupled $^3D_3 - ^3G_3$ waves.
Published: 2020
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2. Measurements of Branching Ratios for $\eta$ Decays into Charged Particles

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullström, C. -O., Heijkenskjöld, L., Hejny, V., Hüsken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wiedner, U., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Nuclear Experiment
Abstract: The WASA-at-COSY experiment has collected $3\times10^{7}$ events with $\eta$-mesons produced via the reaction $pd\rightarrow{^{3}\textrm{He}}\eta$ at $\textrm{T} = 1.0 \textrm{GeV}$. Using this data set, we evaluate the branching ratios of the decays $\eta\to\pi^{+}\pi^{-}\gamma$, $\eta\to e^{+}e^{-}\gamma$, $\eta\to\pi^{+}\pi^{-}e^{+}e^{-}$ and $\eta\to e^{+}e^{-}e^{+}e^{-}$. The branching ratios are normalized to the $\eta\rightarrow\pi^{+}\pi^{-}\pi^{0}$ decay. In addition an upper limit on a $CP$-violating asymmetry in $\eta\rightarrow \pi^{+}\pi^{-}e^{+}e^{-}$ is extracted.
Published: 2015
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3. Measurement of the $np \to np\pi^0\pi^0$ Reaction in Search for the Recently Observed $d^*(2380)$ Resonance

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. --O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Höistad, B., Hüsken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Nuclear Experiment
Abstract: Exclusive measurements of the quasi-free $np \to np\pi^0\pi^0$ reaction have been performed by means of $dp$ collisions at $T_d$ = 2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt s$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated $d^*(2380)$ resonance. Adding the $d^*$ resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of F\"aldt and Wilkin as well Albadajedo and Oset. The ABC effect, {\it i.e.} the low-mass enhancement in the $\pi^0\pi^0$-invariant mass spectrum, is found to be very modest - if present at all, which might pose a problem to some of its interpretations.
Published: 2014
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4. ABC Effect and Resonance Structure in the Double-Pionic Fusion to $^3$He

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. --O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Höistad, B., Hüsken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: Exclusive and kinematically complete measurements of the double pionic fusion to $^3$He have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY. Similar to the observations in the basic $pn \to d \pi^0\pi^0$ reaction and in the $dd \to ^4$He$\pi^0\pi^0$ reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. Differential cross sections are well described by the hypothesis of $d^*$ resonance formation during the reaction process in addition to the conventional $t$-channel $\Delta\Delta$ mechanism. The deduced $d^*$ resonance width can be understood from collision broadening due to Fermi motion of the nucleons in initial and final nuclei.
Published: 2014
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5. Neutron-Proton Scattering in the Context of the $d^*$(2380) Resonance

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. --O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hodana, M., Höistad, B., Hüsken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., {Ż}uprański, P., {Ż}urek, M., Workman, R. L., Briscoe, W. J., and Strakovsky, I. I.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: New data on quasifree polarized neutron-proton scattering, in the region of the recently observed $d^*$ resonance structure, have been obtained by exclusive and kinematically complete high-statistics measurements with WASA at COSY. This paper details the determination of the beam polarization, checks of the quasifree character of the scattering process, on all obtained $A_y$ angular distributions and on the new partial-wave analysis, which includes the new data producing a resonance pole in the $^3D_3$-$^3G_3$ coupled partial waves at ($2380\pm10 - i40\pm5$) MeV -- in accordance with the $d^*$ dibaryon resonance hypothesis. The effect of the new partial-wave solution on the description of total and differential cross section data as well as specific combinations of spin-correlation and spin-transfer observables available from COSY-ANKE measurements at $T_d$ = 2.27 GeV is discussed.
Published: 2014
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6. Toward polarized antiprotons: Machine development for spin-filtering experiments

Author: Weidemann, C., Rathmann, F., Stein, H. J., Lorentz, B., Bagdasarian, Z., Barion, L., Barsov, S., Bechstedt, U., Bertelli, S., Chiladze, D., Ciullo, G., Contalbrigo, M., Dymov, S., Engels, R., Gaisser, M., Gebel, R., Goslawski, P., Grigoriev, K., Guidoboni, G., Kacharava, A., Kamerdzhiev, V., Khoukaz, A., Kulikov, A., Lehrach, A., Lenisa, P., Lomidze, N., Macharashvili, G., Maier, R., Martin, S., Mchedlishvili, D., Meyer, H. O., Merzliakov, S., Mielke, M., Mikirtychiants, M., Mikirtychiants, S., Nass, A., Nikolaev, N. N., Oellers, D., Papenbrock, M., Pesce, A., Prasuhn, D., Retzlaff, M., Schleichert, R., Schröer, D., Seyfarth, H., Soltner, H., Statera, M., Steffens, E., Stockhorst, H., Ströher, H., Tabidze, M., Tagliente, G., Engblom, P. Thörngren, Trusov, S., Valdau, Yu., Vasiliev, A., and Wüstner, P.
Subjects: Physics - Accelerator Physics, Nuclear Experiment
Abstract: The paper describes the commissioning of the experimental equipment and the machine studies required for the first spin-filtering experiment with protons at a beam kinetic energy of $49.3\,$MeV in COSY. The implementation of a low-$\beta$ insertion made it possible to achieve beam lifetimes of $\tau_{\rm{b}}=8000\,$s in the presence of a dense polarized hydrogen storage-cell target of areal density $d_{\rm t}=(5.5\pm 0.2)\times 10^{13}\,\mathrm{atoms/cm^{2}}$. The developed techniques can be directly applied to antiproton machines and allow for the determination of the spin-dependent $\bar{p}p$ cross sections via spin filtering.
Published: 2014
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7. Charge Symmetry Breaking in dd->4He{\pi}0 with WASA-at-COSY

Author: Collaboration, WASA-at-COSY, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. -O., Hanhart, C., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Höistad, B., Hüsken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Nuclear Experiment
Abstract: Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd->4He{\pi}0 have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of p=1.2 GeV/c using the WASA-at-COSY facility. The total cross section amounts to sigma(tot) = (118 +- 18(stat) +- 13(sys) +- 8(ext)) pb and first data on the differential cross section are consistent with s-wave pion production., Comment: 14 pages, 5 figures
Published: 2014
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8. Measurement of the $\eta\to\pi^+\pi^-\pi^0$ Dalitz plot distribution

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. -O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hodana, M., Höistad, B., Hüsken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Martemyanov, B. V., Meißner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: Dalitz plot distribution of the $\eta\to\pi^+\pi^-\pi^0$ decay is determined using a data sample of $1.2\cdot 10^7$ $\eta$ mesons from $pd\to ^3\textrm{He}\eta$ reaction at 1 GeV collected by the WASA detector at COSY., Comment: 13 pages, 6 figures
Published: 2014
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9. Evidence for a New Resonance from Polarized Neutron-Proton Scattering

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Buescher, M., Ciepa, H. Calen. I., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoyev, K., Gullstroem, C. -O., Hauenstein, F., Heijkenskjoeld, L., Hejny, V., Hodana, M., Hoistad, B., Huesken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirrilov, D. A., Kistryn, S., Kleines, H., Klos, B., Krapp, M., Krzemien, W., Kulessa, P., Kupsc, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pysniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Trzcinski, A., Varma, R., Wagner, G. J., Wolke, M., Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zielinski, M. J., Zink, A., Zlomanczuk, J., Zupranski, P., Zurek, M., Workman, R. L., Briscoe, W. J., and Strakovsky, I. I.
Subjects: Nuclear Experiment
Abstract: Exclusive and kinematically complete high-statistics measurements of quasifree polarized $\vec{n}p$ scattering have been performed in the energy region of the narrow resonance structure $d^*$ with $I(J^P) = 0(3^+)$, $M \approx$ 2380 MeV/$c^2$ and $\Gamma \approx$ 70 MeV observed recently in the double-pionic fusion channels $pn \to d\pi^0\pi^0$ and $pn \to d\pi^+\pi^-$. The experiment was carried out with the WASA detector setup at COSY having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process $\vec{d}p \to np + p_{spectator}$. That way the $np$ analyzing power $A_y$ was measured over a large angular range. The obtained $A_y$ angular distributions deviate systematically from the current SAID SP07 NN partial-wave solution. Incorporating the new $A_y$ data into the SAID analysis produces a pole in the $^3D_3 - ^3G_3$ waves as expected from the $d^*$ resonance hypothesis.
Published: 2014
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10. Cross section ratio and angular distributions of the reaction p + d -> 3He + eta at 48.8 MeV and 59.8 MeV excess energy

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. -O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hodana, M., Höistad, B., Hüsken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kłos, B., Kleines, H., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Ohm, H., Ozerianska, I., Passfeld, A., del Rio, E. Perez, Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Węglorz, W., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Nuclear Experiment
Abstract: We present new data for angular distributions and on the cross section ratio of the p + d -> 3He + eta reaction at excess energies of Q = 48.8 MeV and Q = 59.8 MeV. The data have been obtained at the WASA-at-COSY experiment (Forschungszentrum J\"ulich) using a proton beam and a deuterium pellet target. While the shape of obtained angular distributions show only a slow variation with the energy, the new results indicate a distinct and unexpected total cross section fluctuation between Q = 20 MeV and Q = 60 MeV, which might indicate the variation of the production mechanism within this energy interval., Comment: 9 pages, 9 figures
Published: 2014
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11. Measurement of the $pn \to pp\pi^0\pi^-$ Reaction in Search for the Recently Observed Resonance Structure in $d\pi^0\pi^0$ and $d\pi^+\pi^-$ systems

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. --O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hinterberger, F., Hodana, M., Höistad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Klaja, J., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Pluciński, P., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schmidt, A., Schadmand, S., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Tolba, T., Trzciński, A., Varma, R., Wagner, G. J., Węglorz, W., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yuan, X., Zabierowski, J., Zheng, C., Zieliński, M. J., Zipper, W., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Nuclear Experiment
Abstract: Exclusive measurements of the quasi-free $pn \to pp\pi^0\pi^-$ reaction have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt s$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated resonance structure. No ABC effect, {\it i.e.} low-mass enhancement is found in the $\pi^0\pi^-$-invariant mass spectrum -- in agreement with the constraint from Bose statistics that the isovector pion pair can not be in relative s-wave. At the upper end of the covered energy region $t$-channel processes for Roper, $\Delta(1600)$ and $\Delta\Delta$ excitations provide a reasonable description of the data, but at low energies the measured cross sections are much larger than predicted by such processes. Adding a resonance amplitude for the resonance at $m$=~2.37 GeV with $\Gamma$ =~70 MeV and $I(J^P)=~0(3^+)$ observed recently in $pn \to d\pi^0\pi^0$ and $pn \to d\pi^+\pi^-$ reactions leads to an agreement with the data also at low energies.
Published: 2013
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12. Investigation of the dd -> 3He n \pi 0 reaction with the FZ J\'ulich WASA-at-COSY facility

Author: Collaboration, WASA-at-COSY, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. --O., Hanhart, C., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hinterberger, F., Hodana, M., Höistad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Klaja, J., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Pluciński, P., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schmidt, A., Schadmand, S., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Tolba, T., Trzciński, A., Varma, R., Wagner, G. J., Węglorz, W., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yuan, X., Zabierowski, J., Zheng, C., Zieliński, M. J., Zipper, W., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Nuclear Experiment
Abstract: An exclusive measurement of the dd -> 3He n \pi 0 reaction was carried at a beam momentum of p = 1.2 GeV/c using the WASA-at-COSY facility. For the first time data on the total cross section as well as differential distributions were obtained. The data are described with a phenomenological approach based on a combination of a quasi-free model and a partial wave expansion for three-body reaction. The total cross section is found to be \sigma(tot) = (2.89 +- 0.01(stat) +- 0.06(sys) +- 0.29(norm)) \mu b. The contribution of the quasi-free processes (with the neutron being target or beam spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of the phase space. The remaining part of the cross section can be described within a partial wave decomposition indicating the significance of p-wave contributions in the final state., Comment: 9 pages, 7 figures
Published: 2013
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13. Search for a dark photon in the $\pi^0 \to e^+e^-\gamma$ decay

Author: Collaboration, WASA-at-COSY, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C. -O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hinterberger, F., Hodana, M., Höistad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Meißner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N., Pluciński, P., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Shwartz, B., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Tolba, T., Trzciński, A., Varma, R., Wagner, G. J., Wȩglorz, W., Wirzba, A., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieliński, M. J., Zipper, W., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Experiment
Abstract: The presently world largest data sample of pi0 --> gamma e+e- decays containing nearly 5E5 events was collected using the WASA detector at COSY. A search for a dark photon U produced in the pi0 --> gamma U --> gamma e+e- decay from the pp-->pp\pi^0 reaction was carried out. An upper limit on the square of the U-gamma mixing strength parameter epsilon^2 of 5e-6 at 90% CL was obtained for the mass range 20 MeV
Published: 2013
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14. Search for the eta-mesic 4He with WASA-at-COSY detector

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Berlowski, M., Bhatt, H., Buescher, M., Calen, H., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstroem, C. -O., Hauenstein, F., Heijkenskjoeld, L., Hejny, V., Hinterberger, F., Hodana, M., Hoeistad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Klos, B., Krapp, M., Krzemien, W., Kulessa, P., Kupsc, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Niedzwiecki, S., Ohm, H., Ozerianska, I., del Rio, E. Perez, Plucinski, P., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Tolba, T., Trzcinski, A., Varma, R., Vlasov, P., Wagner, G. J., Weglorz, W., Wolke, M., Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zielinski, M. J., Zipper, W., Zlomanczuk, J., Zupranski, P., and Zurek, M.
Subjects: Nuclear Experiment
Abstract: An exclusive measurement of the excitation function for the dd->3Heppi- reaction was performed at the Cooler Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c crossing the kinematic threshold for the eta meson production in the dd->4He-eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the 4He-eta system varied from -51.4MeV to 22MeV. The integrated luminosity in the experiment was determined using the dd->3Hen reaction. The shape of the excitation function for the dd->3Heppi- was examined. No signal of the 4He-eta bound state was observed. An upper limit for the cross-section for the bound state formation and decay in the process dd->(4He-eta)bound->3Heppi- was determined on the 90% confidence level and it varies from 20nb to 27nb for the bound state width ranging from 5MeV to 35MeV, respectively., Comment: 8 pages, 9 figures
Published: 2013
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15. Isospin Decomposition of the Basic Double-Pionic Fusion in the Region of the ABC Effect

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Berlowski, M., Bhatt, H., Büscher, M., Calen, H., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstrom, C. -O., Hauenstein, F., Heijkenskjol, L., Hejny, V., Hinterberger, F., Hodana, M., Hoistad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Klos, B., Krapp, M., Krzemien, W., Kulessa, P., Kupsc, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Niedzwiecki, S., Ohm, H., Ozerianska, I., del Rio, E. Perez, Plucinski, P., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Tolba, T., Trzcinski, A., Varma, R., Vlasov, P., Wagner, G. J., Wkeglorz, W., Wolke, M., Wronska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zielinski, M. J., Zipper, W., Zlomanczuk, J., Zupranski, P., and Zurek, M.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: Exclusive and kinematically complete high-statistics measurements of the basic double pionic fusion reactions pn -> dpi0pi0, pn -> d pi+pi- and pp -> dpi+pi0 have been carried out simultaneously over the energy region of the ABC effect using the WASA detector setup at COSY. Whereas the isoscalar reaction part given by the dpi0pi0 channel exhibits the ABC effect, i.e. a low-mass enhancement in the pipi-invariant mass distribution, as well as the associated resonance structure in the total cross section, the isovector part given by the dpi+pi0 channel shows a smooth behavior consistent with the conventional t-channel Delta Delta process. The dpi+pi- data are very well reproduced by combining the data for isovector and isoscalar contributions, if the kinematical consequences of the isospin violation due to different masses for charged and neutral pions are taken into account.
Published: 2012
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16. ABC Resonance Structure in the Double-Pionic Fusion to 4He

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Berlowski, M., Bhatt, H., Brinkmann, K. T., Buescher, M., Calen, H., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Gullstroem, C. O., Hauenstein, F., Heijkenskjold, L., Hejny, V., Hinterberger, F., Hodana, M., Hoistad, B., Husmann, C., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Mikirtychiants, M., Morsch, H. P., Moskal, P., Nandi, B. K., Niedzwiecki, S., Ohm, H., Ozerianska, I., Pauly, C., del Rio, E. Perez, Petukhov, Y., Plucinski, P., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Serdyuk, V., Shah, N., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Tolba, T., Trzcinski, A., Varma, R., Vlasov, P., Wagner, G. J., Wkeglorz, W., Wolke, M., Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zielinski, M. J., Zipper, W., Zlomanczuk, J., and Zupranski, P.
Subjects: Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract: Exclusive and kinematically complete high-statistics measurements of the double pionic fusion reaction $dd \to ^4$He$\pi^0\pi^0$ have been performed in the energy range 0.8 - 1.4 GeV covering thus the region of the ABC effect, which denotes a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY. Similar to the observation in the basic $pn \to d \pi^0\pi^0$ reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. The maximum occurs at m=2.37 GeV + 2$m_N$, i.e. at the same position as in the basic reaction. The observed resonance width $\Gamma \approx$ 160 MeV can be understood from broadening due to Fermi motion of the nucleons in initial and final nuclei together with collision damping. Differential cross sections are described equally well by the hypothesis of a $pn$ resonance formation during the reaction process.
Published: 2012
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17. Exclusive Measurement of the eta --> pi+ pi- gamma Decay

Author: Adlarson, P., Adolph, C., Augustyniak, W., Bardan, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Berłowski, M., Bhatt, H., Brinkmann, K. -T., Büscher, M., Calén, H., Clement, H., Coderre, D., Czerwiński, E., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Gullström, C. -O., Hanhart, C., Heijkenskjöld, L., Heimlich, J., Hejny, V., Hinterberger, F., Hodana, M., Höistad, B., Jacewicz, M., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Kłos, B., Kren, F., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Leupold, S., Lorentz, B., Magiera, A., Maier, R., Mariański, B., Marciniewski, P., Meißner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Niedźwiecki, S., Ohm, H., Passfeld, A., Pauly, C., del Rio, E. Perez, Petri, T., Petukhov, Y., Piskunov, N., Pluciński, P., Podkopał, P., Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Pyszniak, A., Rausmann, T., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Stollenwerk, F., Szczurek, A., Täschner, A., Terschlüsen, C., Tolba, T., Trzciński, A., Varma, R., Vlasov, P., Wagner, G. J., Węglorz, W., Winnemöller, A., Wirzba, A., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieliński, M. J., Zipper, W., Złomańczuk, J., and Żuprański, P.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: An exclusive measurement of the decay eta --> pi+ pi- gamma has been performed at the WASA facility at COSY. The eta mesons were produced in the fusion reaction pd --> 3He X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13340\pm140 events after background subtraction. The measured pion angular distribution is consistent with a relative p-wave of the two-pion system, whereas the measured photon energy spectrum was found at variance with the simplest gauge invariant matrix element of eta --> pi+ pi- gamma. A parameterization of the data can be achieved by the additional inclusion of the empirical pion vector form factor multiplied by a first-order polynomial in the squared invariant mass of the pi+ pi- system., Comment: 7 pages, 10 figures, submitted to Phys.Lett.B
Published: 2011
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18. \pi^0 \pi^0 Production in Proton-Proton Collisions at Tp=1.4 GeV

Author: Adlarson, P., Adolph, C., Augustyniak, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Berłowski, M., Bhatt, H., Brinkmann, K. --T., Büscher, M., Calén, H., Clement, H., Coderre, D., Czerwiński, E., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryevj, K., Gullström, C. --O., Heijkenskjöld, L., Heimlich, J., Hejny, V., Hinterberger, F., Hodana, M., Höistad, B., Jacewicz, M., Janusz, M., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Kłos, B., Kren, F., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Lorentz, B., Machner, H., Magiera, A., Maier, R., Mariański, B., Marciniewski, P., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Niedźwiecki, S., Ohm, H., Passfeld, A., Pauly, C., del Rio, E. Perez, Petukhov, Y., Piskunov, N., Pluciński, P., Podkopał, P., Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Rausmann, T., Redmer, C. F., Ritman, J., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Szczurek, A., Täschner, A., Tolba, T., Trzciński, A., Varma, R., Vlasov, P., Wagner, G. J., Weglorz, W., Wiedner, U., Winnemöller, A., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieliński, M. J., Zipper, W., Złomańczuk, J., and Zuprański, P.
Subjects: High Energy Physics - Experiment
Abstract: The reaction pp->pppi0pi0 has been investigated at a beam energy of 1.4 GeV using the WASA-at-COSY facility. The total cross section is found to be (324 +- 21_systematic +- 58_normalization) mub. In order to to study the production mechanism, differential kinematical distributions have been evaluated. The differential distributions indicate that both initial state protons are excited into intermediate Delta(1232) resonances, each decaying into a proton and a single pion, thereby producing the pion pair in the final state. No significant contribution of the Roper resonance N*(1440) via its decay into a proton and two pions is found, Comment: Submitted to PLB
Published: 2011
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19. ABC Effect in Basic Double-Pionic Fusion --- Observation of a new resonance?

Author: Adlarson, P., Adolph, C., Augustyniak, W., Baru, V., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Brinkmann, K. -T., Buescher, M., Calen, H., Clement, H., Coderre, D., Czerwinski, E., Doroshkevich, E., Ekstrom, C., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Grishina, V., Gullstrom, C. -O., Hampe, J., Hanhart, C., Heijkenskj, L., Hejny, V., Hinterberger, F., Hodana, M., Hoistad, B., Jacewicz, M., Janusz, M., Jany, A., Jany, B. R., Jarczyk, L., Jaus, J., Johansson, T., Kamys, B., Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Klos, B., Kren, F., Krzemien, W., Kulessa, P., Kullander, S., Kupsc, A., Lalwani, K., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Mikirtychiants, M., Moskal, P., Morsch, H. -P., Nandi, B. K., Ohm, H., Passfeld, A., Pauly, C., del Rio, E. Perez, Petukhov, Y., Piskunov, N., Plucinski, P., Podkopal, P., Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Rausmann, T., Redmer, C. F., Ritman, J., Roy, A., Ruber, R. J. M. Y., Rudy, Z., Schadmand, S., Schmidt, A., Schroeder, W., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Tolba, T., Trzcinski, A., Varma, R., Vlasov, P., Wagner, G. J., Weglorz, W., Winnemoeller, A., Wirzba, A., Wolke, M., Wronska, A., Wuestner, P., Wurm, P., Yurev, L., Zabierowski, J., Zielinski, M. J., Zipper, W., Zlomanczuk, J., and Zupranski, P.
Subjects: Nuclear Experiment
Abstract: We report on a high-statistics measurement of the basic double pionic fusion reaction $pn \to d\pi^0\pi^0$ over the energy region of the so-called ABC effect, a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The measurements were performed with the WASA detector setup at COSY. The data reveal the ABC effect to be associated with a Lorentzian shaped energy dependence in the integral cross section. The observables are consistent with a resonance with $I(J^P) =0(3^+)$ in both $pn$ and $\Delta\Delta$ systems. Necessary further tests of the resonance interpretation are discussed.
Published: 2011
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20. Measurement of the Spin-Dependence of the pbar-p Interaction at the AD-Ring

Author: Barschel, C., Bechstedt, U., Dietrich, J., Dolfus, N., Engels, R., Gebel, R., Hadamek, H., Haidenbauer, J., Hanhart, C., Kacharava, A., Krol, G., Kueven, M., Langenberg, G., Lehrach, A., Lorentz, B., Maier, R., Martin, S., Meissner, U. -G., Nekipelov, M., Nikolaev, N. N., Oellers, D., d'Orsaneo, G., Prasuhn, D., Rathmann, F., Retzlaff, M., Sarkadi, J., Schleichert, R., Seyfarth, H., Sibirtsev, A., Spoelgen, D., Stein, H. J., Stockhorst, H., Stroeher, H., Weidemann, Chr., Welsch, D., Wieder, P., Barion, L., Bertelli, S., Carassiti, V., Ciullo, G., Contalbrigo, M., Cotta-Ramusino, A., Dalpiaz, P. F., Drago, A., Guidoboni, G., Lenisa, P., Pappalardo, L., Stancari, G., Stancari, M., Statera, M., Azarian, T., Kulikov, A., Kurbatov, V., Macharashvili, G., Merzliakov, S., Meshkov, I. N., Smirnov, A., Tsirkov, D., Uzikov, Yu., Barsov, S., Belostotski, S., Grigoryev, K., Kravtsov, P., Mikirtychiants, M., Mikirtychiants, S., Vasilyev, A., Esser, F. M., Greven, R., Hansen, G., Jadgfeld, F., Klehr, F., Soltner, H., Straatmann, H., Chiladze, D., Garishvili, A., Lomidze, N., Mchedlishvili, D., Nioradze, M., Tabidze, M., Akopov, N., Avetisyan, A., Elbakyan, G., Marukyan, H., Taroian, S., Benati, P., Erven, W., Kayser, F. J., Kleines, H., Wuestner, P., Bruncko, D., Ferencei, J., Musinsky, J., Urban, J., Augustyniak, W., Marianski, B., Trzcinski, A., Zupranski, P., Dymov, S., Nass, A., Steffens, E., Rathsman, K., Tegner, P. E., Engblom, P. Thoerngren, De Leo, R., Tagliente, G., Kaempfer, B., Trusov, S., Buttimore, N., and Meyer, H. O.
Subjects: Nuclear Experiment
Abstract: We propose to use an internal polarized hydrogen storage cell gas target in the AD ring to determine for the first time the two total spin-dependent pbar-p cross sections sigma_1 and sigma_2 at antiproton beam energies in the range from 50 to 450 MeV. The data obtained are of interest by themselves for the general theory of pbar-p interactions since they will provide a first experimental constraint of the spin-spin dependence of the nucleon-antinucleon potential in the energy range of interest. In addition, measurements of the polarization buildup of stored antiprotons are required to define the optimum parameters of a future, dedicated Antiproton Polarizer Ring (APR), intended to feed a double-polarized asymmetric pbar-p collider with polarized antiprotons. Such a machine has recently been proposed by the PAX collaboration for the new Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt, Germany. The availability of an intense stored beam of polarized antiprotons will provide access to a wealth of single- and double-spin observables, thereby opening a new window on QCD spin physics., Comment: 51 pages, 23 figures, proposal submitted to the SPS committee of CERN
Published: 2009

21. Polarizing a stored proton beam by spin flip?

Author: Oellers, D., Barion, L., Barsov, S., Bechstedt, U., Benati, P., Bertelli, S., Chiladze, D., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Dietrich, J., Dolfus, N., Dymov, S., Engels, R., Erven, W., Garishvili, A., Gebel, R., Goslawski, P., Grigoryev, K., Hadamek, H., Kacharava, A., Khoukaz, A., Kulikov, A., Langenberg, G., Lehrach, A., Lenisa, P., Lomidze, N., Lorentz, B., Macharashvili, G., Maier, R., Martin, S., Merzliakov, S., Meshkov, I. N., Meyer, H. O., Mielke, M., Mikirtychiants, M., Mikirtychiants, S., Nass, A., Nekipelov, M., Nikolaev, N. N., Nioradze, M., d'Orsaneo, G., Papenbrock, M., Prasuhn, D., Rathmann, F., Sarkadi, J., Schleichert, R., Smirnov, A., Seyfarth, H., Sowinski, J., Spoelgen, D., Stancari, G., Stancari, M., Statera, M., Steffens, E., Stein, H. J., Stockhorst, H., Straatmann, H., Stroeher, H., Tabidze, M., Tagliente, G., Engblom, P. Thoerngren, Trusov, S., Vasilyev, A., Weidemann, Chr., Welsch, D., Wieder, P., Wuestner, P., and Zupranski, P.
Subjects: Nuclear Experiment
Abstract: We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin flip cross section in low-energy electron-proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam., Comment: 18 pages, 6 figures
Published: 2009
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22. Hyper-Polarized Deuterium Molecules: An Option to Produce and Store Polarized Fuel for Nuclear Fusion?

Author: Engels, Ralf, Farren, G., Grigoryev, K., Mikirtychiants, M., Rathmann, F., Seyfarth, H., Ströher, H., Kochenda, L., Kravtsov, P., Trofimov, V., Vasilyev, Alexander, Vznudaev, M., Paetz gen. Schieck, H., Ciullo, Giuseppe, editor, Engels, Ralf, editor, Büscher, Markus, editor, and Vasilyev, Alexander, editor
Published: 2016
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23. New experimental upper limit of the electron–proton spin-flip cross-section

Author: Oellers, D., Weidemann, C., Lenisa, P., Meyer, H.O., Rathmann, F., Trusov, S., Augustyniak, W., Bagdasarian, Z., Barion, L., Barsov, S., Bechstedt, U., Bertelli, S., Carassiti, V., Chiladze, D., Ciullo, G., Contalbrigo, M., Dalpiaz, P.F., Dymov, S., Engels, R., Gaisser, M., Gebel, R., Goslawski, P., Grigoriev, K., Guidoboni, G., Kacharava, A., Khoukaz, A., Kulikov, A., Kleines, H., Langenberg, G., Lehrach, A., Lomidze, N., Lorentz, B., Macharashvili, G., Maier, R., Marianski, B., Martin, S., Mchedlishvili, D., Merzliakov, S., Meshkov, I.N., Mielke, M., Mikirtychiants, M., Mikirtychiants, S., Nass, A., Nikolaev, N., Nioradze, M., Papenbrock, M., Pappalardo, L., Pesce, A., Prasuhn, D., Sarkadi, J., Schleichert, R., Smirnov, A., Seyfarth, H., Statera, M., Steffens, E., Stein, H.J., Stockhorst, H., Stro¨her, H., Tabidze, M., Tagliente, G., Tho¨rngren Engblom, P., Trzcinski, A., Valdau, Y., Vasiliev, A., Wüstner, P., and Zupranski, P.
Published: 2014
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24. Differential cross sections for neutron-proton scattering in the region of the d∗(2380) dibaryon resonance

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, Kirill, Gullström, C.--O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hodana, M., Höistad, B., Hüsken, N., Jany, A., Jany, B. R., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, P., Ohm, H., Ozerianska, I., Perez Del Rio, E., Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zink, A., Złomańczuk, J., Zurek, M., Workman, R. L., Briscoe, W. J., Strakovsky, I. I., and Švarc, A.
Subjects: resonance: pole, p: spectator, p n: scattering, partial wave analysis, Juelich COSY PS, deuteron: beam, dibaryon, kinematics, differential cross section, analyzing power, angular distribution, WASA, +n+p+p%22">deuteron p --> n p p, experimental results, hydrogen: target
Abstract: Physical review / C 102(1), 015204 (2020). doi:10.1103/PhysRevC.102.015204, Published by The American Institute of Physics, Woodbury, NY
Published: 2020
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25. Differential cross sections for neutron-proton scattering in the region of the d* (2380) dibaryon resonance

Author: Adlarson, Patrik, Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Buescher, M., Calén, Hans, Ciepal, I, Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C-O, Hauenstein, F., Heijkenskjöld, L., Hejny, V, Hodana, M., Höistad, B., Huesken, N., Jany, A., Jany, B. R., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krapp, M., Krzemien, W., Kulessa, P., Kupsc, Andrzej, Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, Pawel, Marianski, B., Mikirtychiants, M., Morsch, H-P, Moskal, P., Ohm, H., Ozerianska, I, del Rio, E. Perez, Piskunov, N. M., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V, Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V, Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Trzcinski, A., Varma, R., Wolke, Magnus, Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zielinski, M. J., Zink, A., Zlomanczuk, Jozef, Zupranski, P., Zurek, M., Workman, R. L., Briscoe, W. J., Strakovsky, I. I., Svarc, A., Adlarson, Patrik, Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Buescher, M., Calén, Hans, Ciepal, I, Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C-O, Hauenstein, F., Heijkenskjöld, L., Hejny, V, Hodana, M., Höistad, B., Huesken, N., Jany, A., Jany, B. R., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krapp, M., Krzemien, W., Kulessa, P., Kupsc, Andrzej, Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, Pawel, Marianski, B., Mikirtychiants, M., Morsch, H-P, Moskal, P., Ohm, H., Ozerianska, I, del Rio, E. Perez, Piskunov, N. M., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V, Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V, Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Trzcinski, A., Varma, R., Wolke, Magnus, Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zielinski, M. J., Zink, A., Zlomanczuk, Jozef, Zupranski, P., Zurek, M., Workman, R. L., Briscoe, W. J., Strakovsky, I. I., and Svarc, A.
Abstract: Differential cross sections have been extracted from exclusive and kinematically complete high-statistics measurements of quasifree polarized (n) over barp scattering performed in the energy region of the d* (2380) dibaryon resonance covering the range of beam energies T-n = 0.98-1.29 GeV (root s = 2.32-2.44 GeV). The experiment was carried out with the WASA-at-COSY setup having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process dp -> np + p(spectator). In this way the np differential cross section sigma (Theta) was measured over a large angular range. The obtained angular distributions complement the corresponding analyzing power A(y)(Theta) measurements published previously. A SAID partial-wave analysis incorporating the new data strengthens the finding of a resonance pole in the coupled D-3(3) - (3)G(3) waves.
Published: 2020
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26. Charge symmetry breaking in dd→He4π0 with WASA-at-COSY

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F.S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.O., Hanhart, C., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Höistad, B., Hüsken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F.A., Khoukaz, A., Kirillov, D.A., Kistryn, S., Kleines, H., Kłos, B., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.P., Moskal, P., Ohm, H., Ozerianska, I., Perez del Rio, E., Piskunov, N.M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C.F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieliński, M.J., Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Deuteron–deuteron interactions, Charge symmetry breaking, Nuclear Theory, Pion production, Nuclear Experiment, lcsh:Physics, lcsh:QC1-999
Abstract: Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd→He4π0 have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of pd=1.2 GeV/c using the WASA-at-COSY facility. The total cross section amounts to σtot=(118±18stat±13sys±8ext) pb and first data on the differential cross section are consistent with s-wave pion production. Keywords: Charge symmetry breaking, Deuteron–deuteron interactions, Pion production
Published: 2014

27. Measurement of the → Reaction in Search for the Recently Observed (2380) Resonance

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F.S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Höistad, B., Hüsken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F.A., Khoukaz, A., Kirillov, D.A., Kistryn, S., Kleines, H., Kłos, B., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.P., Moskal, P., Ohm, H., Ozerianska, I., Perez del Rio, E., Piskunov, N.M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wagner, G.J., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieliński, M.J., Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Abstract: Exclusive measurements of the quasi-free np→npπ0π0 reaction have been performed by means of dp collisions at Td=2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region s=(2.35–2.46) GeV, which includes the region of the ABC effect and its associated d⁎(2380) resonance. Adding the d⁎ resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of Fäldt and Wilkin as well with those of Albadajedo and Oset. The ABC effect, i.e. the low-mass enhancement in the π0π0-invariant mass spectrum, is found to be very modest – if present at all, which might pose a problem to some of its interpretations.
Published: 2015

28. ABC effect and resonance structure in the double-pionic fusion to He-3

Author: ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BONDAR, A, BUSCHER, M, CALEN, H, CIEPAL, I, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DEMMICH, K, DOROSHKEVICH, E, ENGELS, R, ERVEN, A, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HAUENSTEIN, F, HEIJKENSKJOLD, L, HEJNY, V, HOISTAD, B, HUSKEN, N, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHOUKAZ, A, KIRILLOV, DA, KISTRYN, S, KLEINES, H, KLOS, B, KRZEMIEN, W, KULESSA, P, KUPSC, A, KUZMIN, A, LALWANI, K, LERSCH, D, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, OHM, H, OZERIANSKA, I, DEL RIO, EP, PISKUNOV, NM, PODKOPAL, P, PRASUHN, D, PRICKING, A, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SEFZICK, T, SERDYUK, V, SHWARTZ, B, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TASCHNER, A, TRZCINSKI, A, VARMA, R, WAGNER, GJ, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YAMAMOTO, A, YUREV, L, ZABIEROWSKI, J, ZIELINSKI, MJ, ZINK, A, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M
Subjects: Gev-C, Near-Threshold, Enhancement, Dibaryons, Proton-Proton Collisions, Pi-Pi Interaction, Pi(0)Pi(0) Production, Meson Production, Isospin Decomposition, Nuclear-Matter
Abstract: Exclusive and kinematically complete measurements of the double pionic fusion to He-3 have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the pi pi-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY (the cooler synchrotron at Forschungszentrum Julich). Similar to the observations in the basic pn -> d pi(0)pi(0) reaction and in the dd -> He-4 pi(0)pi(0) reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. Differential cross sections are well described by the hypothesis of d* resonance formation during the reaction process in addition to the conventional t-channel Delta Delta mechanism. The deduced d* resonance width can be understood from collision broadening due to Fermi motion of the nucleons in initial and final nuclei.
Published: 2015

29. Measurement of the $np\rightarrow np\pi^{0} \pi ^{0}$ reaction in search for the recently observed $d^{\ast}$ (2380) resonance

Author: Adlarson, P., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, Izabela, Clement, H., Coderre, D., Czerwiński, Eryk, Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.-O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Höistad, B., Hüsken, N., Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, Stanisław, Kleines, H., Kłos, B., Krzemień, Wojciech, Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, Andrzej, Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Ohm, H., Schätti - Ozerianska, Iryna, Perez del Rio, Elena, Piskunov, N. M., Podkopał, Paweł, Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, Andrzej, Ritman, J., Roy, A., Rudy, Zbigniew, Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieliński, Marcin, Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: ABC effect and resonance structure, dibaryon resonance, two-pion production
Published: 2015

30. ABC effect and resonance structure in the double-pionic fusion to $^{3}He$

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., H��istad, B., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wagner, G. J., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, High Energy Physics - Experiment
Abstract: Exclusive and kinematically complete measurements of the double pionic fusion to $^{3}He$ have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY (the cooler synchrotron at Forschungszentrum Jülich). Similar to the observations in the basic $pn \rightarrow d \pi^{0} \pi^{0}$ reaction and in the $dd \rightarrow ^{4} He \pi^{0} \pi^{0}$ reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. Differential cross sections are well described by the hypothesis of $d^{\ast}$ resonance formation during the reaction process in addition to the conventional t-channel $\Delta \Delta$ mechanism. The deduced $d^{\ast}$ resonance width can be understood from collision broadening due to Fermi motion of the nucleons in initial and final nuclei.
Published: 2015

31. Measurements of branching ratios for eta decays into charged particles

Author: Adlarson, Patrik, Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Bondar, A., Buescher, M., Calén, Hans, Ciepal, I., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, Kjell, Goldenbaum, F., Goswami, A., Grigoryev, K., Gullström, Carl-Oskar, Heijkenskjöld, Lena, Hejny, V., Huesken, N., Jarczyk, L., Johansson, Tord, Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, Andrzej, Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marcinievski, Pawel, Marianski, B., Mikirtychiants, M., Morsch, H. -P, Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, Damian, Pysz, K., Pyszniak, Andrzej, Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Trzcinski, A., Varma, R., Wiedner, U., Wolke, Magnus, Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zielinski, M. J., Zink, A., Zlomanczuk, Jozef, Zupranski, P., Zurek, M., Adlarson, Patrik, Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Bondar, A., Buescher, M., Calén, Hans, Ciepal, I., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, Kjell, Goldenbaum, F., Goswami, A., Grigoryev, K., Gullström, Carl-Oskar, Heijkenskjöld, Lena, Hejny, V., Huesken, N., Jarczyk, L., Johansson, Tord, Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, Andrzej, Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marcinievski, Pawel, Marianski, B., Mikirtychiants, M., Morsch, H. -P, Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, Damian, Pysz, K., Pyszniak, Andrzej, Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Trzcinski, A., Varma, R., Wiedner, U., Wolke, Magnus, Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zielinski, M. J., Zink, A., Zlomanczuk, Jozef, Zupranski, P., and Zurek, M.
Abstract: The WASA-at-COSY experiment has collected 3 x 10(7) events with eta mesons produced via the reaction pd -> He-3 eta at T = 1.0 GeV. Using this data set, we evaluate the branching ratios of the decays eta -> pi(+)pi(-)gamma, eta -> e(+)e(-)gamma, eta -> pi(+)pi(-)e(+)e(-), and eta -> e(+)e(-)e(+)e(-). The branching ratios are normalized to the eta -> pi(+)pi(-) pi(0) decay. In addition an upper limit on a CP-violating asymmetry in eta -> pi(+)pi(-)e(+)e(-) is extracted.
Published: 2016
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32. Measurement of the $\eta \rightarrow \pi ^{+}\pi ^{-}\pi ^{0}$ Dalitz plot distribution

Author: Adlarson, P., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calén, H., Ciepał, Izabela, Clement, H., Coderre, D., Czerwiński, Eryk, Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.-O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hodana, Małgorzata, Höistad, B., Hüsken, N., Jany, Anna, Jany, Benedykt, Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, Stanisław, Kleines, H., Kłos, B., Krzemień, Wojciech, Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, Andrzej, Maier, R., Marciniewski, P., Mariański, B., Martemyanov, B. V., Meißner, U.-G., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Ohm, H., Schätti - Ozerianska, Iryna, Perez del Rio, Elena, Piskunov, N. M., Podkopał, Paweł, Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, Andrzej, Redmer, C. F., Ritman, J., Roy, A., Rudy, Zbigniew, Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieliński, Marcin, Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: High Energy Physics::Phenomenology, High Energy Physics::Experiment, Nuclear Experiment
Abstract: The Dalitz plot distribution of the $\eta \rightarrow \pi ^{+}\pi ^{-}\pi ^{0}$ decay is determined by using a data sample of $1.2×10^{7} \eta$ mesons from the $pd\rightarrow^{3}He \eta$ reaction at 1 GeV collected by the WASA detector at COSY.
Published: 2014

33. Cross section ratio and angular distributions of the reaction $p + d \rightarrow ^{3}He + \it{\eta}$ at 48.8 MeV and 59.8 MeV excess energy

Author: Adlarson, P., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, H., Ciepał, Izabela, Clement, H., Coderre, D., Czerwiński, Eryk, Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.-O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hodana, Małgorzata, Höistad, B., Hüsken, N., Jany, Anna, Jany, Benedykt, Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, Stanisław, Kłos, B., Kleines, H., Krapp, M., Krzemień, Wojciech, Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, Andrzej, Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Ohm, H., Schätti - Ozerianska, Iryna, Passfeld, A., Perez del Rio, Elena, Piskunov, N. M., Podkopał, Paweł, Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, Andrzej, Redmer, C. F., Ritman, J., Roy, A., Rudy, Zbigniew, Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Węglorz, W., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieliński, Marcin, Zink, A., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Physics::Accelerator Physics, Nuclear Experiment
Abstract: We present new data for angular distributions and on the cross section ratio of the $p + d \rightarrow ^{3}He + \it{\eta}$ reaction at excess energies of $\it{Q}$ = 48.8 MeV and $\it{Q}$ = 59.8 MeV. The data have been obtained at the WASA-at-COSY experiment (Forschungszentrum Jülich) using a proton beam and a deuterium pellet target. While the shape of obtained angular distributions show only a slow variation with the energy, the new results indicate a distinct and unexpected total cross section fluctuation between $\it{Q}$ = 20 MeV and $\it{Q}$ = 60 MeV, which might indicate the variation of the production mechanism within this energy interval.
Published: 2014

34. Charge Symmetry Breaking in dd->4He��0 with WASA-at-COSY

Author: COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., H��istad, B., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd->4He��0 have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of p=1.2 GeV/c using the WASA-at-COSY facility. The total cross section amounts to sigma(tot) = (118 +- 18(stat) +- 13(sys) +- 8(ext)) pb and first data on the differential cross section are consistent with s-wave pion production., 14 pages, 5 figures
Published: 2014
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35. Measurement of the $��\to��^+��^-��^0$ Dalitz plot distribution

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hodana, M., H��istad, B., H��sken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Martemyanov, B. V., Mei��ner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics - Experiment (hep-ex), Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Dalitz plot distribution of the $��\to��^+��^-��^0$ decay is determined using a data sample of $1.2\cdot 10^7$ $��$ mesons from $pd\to ^3\textrm{He}��$ reaction at 1 GeV collected by the WASA detector at COSY., 13 pages, 6 figures
Published: 2014
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36. Charge symmetry breaking in dd -> He-4 pi(0) with WASA-at-COSY

Author: Adlarson, Patrik, Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Bondar, A., Buescher, M., Calén, Hans, Ciepal, I., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, Kjell E. I., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, Carl-Oscar, Hanhart, C., Hauenstein, F., Heijkenskjöld, Lena, Hejny, V., Höistad, Bo, Huesken, N., Jarczyk, L., Johansson, Tord, Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, Andrzej, Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, Pawel, Marianski, B., Mikirtychiants, M., Morsch, H. -P, Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, Damian, Pyszw, K., Pyszniak, Andrzej, Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroher, H., Szczurek, A., Taschner, A., Trzcinski, A., Varma, R., Wolke, Magnus, Wronska, A., Wustner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zielinski, M. J., Zink, A., Zlomanczuk, Jozef, Zupranski, P., and Zurek, M.
Subjects: Nuclear Theory, Charge symmetry breaking, Physical Sciences, Fysik, Pion production, Nuclear Experiment, Deuteron-deuteron interactions
Abstract: Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd -> He-4 pi(0) have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of p(d) = 1.2GeV/c using the WASA-at-COSY facility. The total cross section amounts to sigma(tot) =(118 +/- 18(stat) +/- 13(sys) +/- 8(ext)) p band first data on the differential cross section are consistent with s-wave pion production.
Published: 2014

37. Charge symmetry breaking in $dd\rightarrow ^{4}He\pi ^{0}$ with WASA-at-COSY

Author: Adlarson, P., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Berłowski, M., Bhatt, H., Bondar, A., Calén, H., Ciepał, Izabela, Clement, H., Coderre, D., Czerwiński, Eryk, Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Gullström, C.-O., Hanhart, C., Heijkenskjöld, L., Hejny, V., Höistad, B., Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Khan, F. A., Khoukaz, A., Kirillov, D. A., Kleines, H., Kłos, B., Krzemień, Wojciech, Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Magiera, Andrzej, Maier, R., Marciniewski, P., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Schätti - Ozerianska, Iryna, Perez del Rio, Elena, Piskunov, N. M., Prasuhn, D., Pricking, A., Pszczel, D., Pyszniak, Andrzej, Redmer, C. F., Ritman, J., Roy, A., Sawant, S., Schadmand, S., Sefzick, T., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Ströher, H., Täschner, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieliński, Marcin, Zink, A., Żupranski, P., Żurek, M., Bergmann, F. S., Büscher, M., Złomańczuk, J., Yurev, L., Szczurek, A., Stephan, E., Serdyuk, V., Rudy, Zbigniew, Pysz, K., Podkopał, Paweł, Ohm, H., Mariański, B., Lorentz, B., Kistryn, Stanisław, Kemmerling, G., Hüsken, N., Hauenstein, F., Goswami, A., and Föhl, K.
Subjects: charge symmetry breaking, deuteron–deuteron interactions, pion production, Nuclear Experiment
Abstract: Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd\rightarrow $^{4}He\pi ^{0}$ have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of $p_{d}=1.2$ GeV/c using the WASA-at-COSY facility. The total cross section amounts to $\sigma _{tot} = (118 \pm 18_{stat} \pm 13_{sys} \pm 8_{ext}) pb$ and first data on the differential cross section are consistent with s-wave pion production.
Published: 2014

38. Charge symmetry breaking in dd -> He-4 [pi](0) with WASA-at-COSY

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Berłowski, M., Bhatt, H., Bondar, A., Buscher, M., Calen, H., Ciepał, I., Clement, H., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieliński, M.J., Zink, A., Złomańczuk, J., Żuprański, P., Żurek, M., Coderre, D., Czerwiński, C., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Fohl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstrom, C.O., Hanhart, C., Hauenstein, F., Heijkenskjold, L., Hejny, V., Hoistad, B., Husken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F.A., Khoukaz, A., Kirillov, D.A., Kistryn, S., Kleines, H., Kłos, Barbara, Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.P., Moskal, P., Ohm, K., Ozerianska, I., del Rio, E.P., Piskunov, N.M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pyszw, K., Pyszniak, A., Redmer, C.F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, Elżbieta, Sterzenbach, G., Stockhorst, H., Stroher, H., Szczurek, A., Taschner, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, A., and Wustner, P.
Subjects: Nuclear Theory, Charge symmetry breaking, Pion production, Nuclear Experiment, Deuteron-deuteron interactions
Abstract: Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd -> He-4 pi(0) have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of p(d) = 1.2GeV/c using the WASA-at-COSY facility. The total cross section amounts to sigma(tot) =(118 +/- 18(stat) +/- 13(sys) +/- 8(ext)) p band first data on the differential cross section are consistent with s-wave pion production.
Published: 2014

39. Search for a dark photon in the $��^0 \to e^+e^-��$ decay

Author: COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Krapp, M., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mei��ner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N., Pluci��ski, P., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Shwartz, B., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Tolba, T., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wirzba, A., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The presently world largest data sample of pi0 --> gamma e+e- decays containing nearly 5E5 events was collected using the WASA detector at COSY. A search for a dark photon U produced in the pi0 --> gamma U --> gamma e+e- decay from the pp-->pp��^0 reaction was carried out. An upper limit on the square of the U-gamma mixing strength parameter epsilon^2 of 5e-6 at 90% CL was obtained for the mass range 20 MeV, 16 pages, 8 figures; improved analysis extending the exclusion region to 20 MeV
Published: 2013
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40. Search for $\eta$-mesic ^{4}He with the WASA-at-COSY detector

Author: Adlarson, P., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Bednarski, Tomasz, Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, Hans, Clement, H., Coderre, D., Czerwiński, Eryk, Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.-O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hinterberger, F., Hodana, Małgorzata, Höistad, B., Jany, Anna, Jany, Benedykt, Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, Stanisław, Klaja, Joanna, Kleines, H., Kłos, B., Krapp, M., Krzemień, Wojciech, Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, Andrzej, Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Nandi, B. K., Niedźwiecki, Szymon, Ohm, H., Schätti - Ozerianska, Iryna, Perez del Rio, Elena, Pluciński, P., Podkopał, Paweł, Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, Andrzej, Redmer, C. F., Ritman, J., Roy, A., Rudy, Zbigniew, Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Tolba, T., Trzciński, A., Varma, R., Vlasov, P., Wagner, G. J., Węglorz, W., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieliński, Marcin, Zipper, W., Złomańczuk, J., Żuprański, P., and Żurek, M.
Published: 2013

41. Search for eta-mesic He-4 with the WASA-at-COSY detector

Author: ADLARSON, P, AUGUSTYNIAK, W, BARDAN, W, BASHKANOV, M, BEDNARSKI, T, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BUSCHER, M, CALEN, H, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DEMMICH, K, DOROSHKEVICH, E, ENGELS, R, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GOSWAMI, A, GRIGORYEV, K, GULLSTROM, CO, HAUENSTEIN, F, HEIJKENSKJOLD, L, HEJNY, V, HINTERBERGER, F, HODANA, M, HOISTAD, B, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAN, FA, KHOUKAZ, A, KISTRYN, S, KLAJA, J, KLEINES, H, KLOS, B, KRAPP, M, KRZEMIEN, W, KULESSA, P, KUPSC, A, LALWANI, K, LERSCH, D, LI, L, LORENTZ, B, MAGIERA, A, MAIER, R, MARCINIEWSKI, P, MARIANSKI, B, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, NANDI, BK, NIEDZWIECKI, S, OHM, H, OZERIANSKA, I, DEL RIO, EP, PLUCINSKI, P, PODKOPAL, P, PRASUHN, D, PRICKING, A, PSZCZEL, D, PYSZ, K, PYSZNIAK, A, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SCHMIDT, A, SEFZICK, T, SERDYUK, V, SHAH, N, SIEMASZKO, M, SIUDAK, R, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STEPHAN, E, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TOLBA, T, TRZCINSKI, A, VARMA, R, VLASOV, P, WAGNER, GJ, WEGLORZ, W, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YAMAMOTO, A, YUAN, X, YUREV, L, ZABIEROWSKI, J, ZHENG, C, ZIELINSKI, MJ, ZIPPER, W, ZLOMANCZUK, J, ZUPRANSKI, P, and ZUREK, M
Subjects: Photoproduction, Mesons, Bound-States, Nuclei
Abstract: An exclusive measurement of the excitation function for the dd -> (3)Hep pi(-) reaction was performed at the Cooler Synchrotron COSY-Julich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 to 2.400 GeV/c crossing the kinematic threshold for the eta-meson production in the dd -> He-4 eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the He-4-eta system varied from -51.4 to 22 MeV. The integrated luminosity in the experiment was determined using the dd -> (3)Hen reaction. The shape of the excitation function for the dd -> (3)Hep pi(-) reaction was examined. No signal of the He-4-eta bound state was observed. An upper limit for the cross section for the bound state formation and decay in the process dd -> (He-4-eta)(bound) -> (3)Hep pi(-) was determined on the 90% confidence level and it varies from 20 to 27 nb for the bound state width ranging from 5 to 35 MeV, respectively. DOI: 10.1103/PhysRevC.87.035204
Published: 2013

42. Search for a dark photon in the $\pi ^{0}\rightarrow e^{+}e^{-}\gamma$ decay

Author: Adlarson, P., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Berłowski, M., Bhatt, H., Bondar, A., Calén, Hans, Ciepał, Izabela, Clement, H., Coderre, D., Czerwiński, Eryk, Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Goldenbaum, E., Goslawski, P., Goswami, A., Gullström, C.-O., Hauenstein, F., Hejny, V., Hinterberger, F., Hodana, Małgorzata, Jany, Anna, Jany, Benedykt, Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Kemmerling, G., Khan, F. A., Khoukaz, A., Klaja, Joanna, Kleines, H., Kirillov, D. A., Kłos, B., Krapp, M., Krzemień, Wojciech, Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Nandi, B. K., Ohm, H., Schätti - Ozerianska, Iryna, Perez del Rio, Elena, Pluciński, P., Podkopał, Paweł, Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, Andrzej, Ritman, J., Roy, A., Rudy, Zbigniew, Sawant, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Shwartz, B., Siemaszko, M., Siudak, R., Skorodko, T., Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Tolba, T., Trzciński, A., Varma, R., Węglorz, W., Wirzba, A., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zipper, W., Złomańczuk, J., Żuprański, P., Bergmann, F. S., Büscher, M., Fransson, K., Grigoryev, K., Heijkenskjöld, L., Höistad, B., Kistryn, Stanisław, Kuzmin, A., Magiera, Andrzej, Meißner, U.-G., Piskunov, N. M., Pricking, A., Redmer, C. F., Schadmand, S., Wagner, G. J., Skurzok, Magdalena, Zieliński, Marcin, and Żurek, M.
Subjects: dark forces, gauge vector boson
Published: 2013

43. Investigation of the dd\rightarrow $^{3}Hen\pi ^{0}$ reaction with the FZ Jülich WASA-at-COSY facility

Author: Adlarson, P., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Berłowski, M., Bhatt, H., Büscher, M., Ciepał, Izabela, Clement, H., Coderre, D., Czerwiński, Eryk, Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Fedorets, P., Föhl, K., Fransson, K., Goslawski, P., Goswami, A., Grigoryev, K., Hanhart, C., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hinterberger, F., Hodana, M., Höistad, B., Jany, Benedykt, Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Khan, F. A., Khoukaz, A., Kirillov, D. A., Klaja, Joanna, Kleines, H., Kłos, B., Krapp, M., Kulessa, P., Kupść, A., Lalwani, K., Li, L., Lorentz, B., Magiera, Andrzej, Maier, R., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Nandi, B. K., Ohm, H., Schätti - Ozerianska, Iryna, Piskunov, N. M., Pluciński, P., Podkopał, Paweł, Pricking, A., Pszczel, D., Pysz, K., Redmer, C. F., Ritman, J., Roy, A., Rudy, Zbigniew, Schmidt, A., Schadmand, S., Sefzick, T., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stephan, E., Sterzenbach, G., Stockhorst, H., Szczurek, A., Tolba, T., Trzciński, A., Varma,R., Wagner, G. J., Węglorz, W., Wolke, M., Wrońska, Aleksandra, Wurm, P., Yamamoto, A., Yuan, X., Zabierowski,J., Zheng, C., Zieliński, Marcin, Zipper, W., Złomańczuk, J., Żurek, M., Bergmann, F. S., Calén, Hans, Goldenbaum, F., Eyrich, W., Gullström, C.-O., Jany, Anna, Kemmerling, G., Kistryn, Stanisław, Krzemień, Wojciech, Lersch, D., Marciniewski, P., Perez del Rio, Elena, Prasuhn, D., Pyszniak, Andrzej, Sawant, S., Serdyuk, V., Stepaniak, J., Ströher, H., Wüstner, P., and Żuprański, P.
Abstract: An exclusive measurement of the dd\rightarrow $^{3}Hen\pi^{0}$ eaction was carried out at a beam momentum of $p_{d}$=1.2 GeV/c using the WASA-at-COSY facility. Information on the total cross section as well as differential distributions was obtained. The data are described by a phenomenological approach based on a combination of a quasifree model and a partial wave expansion for the three-body reaction. The total cross section is found to be $\sigma _{tot}= \left ( 2.89\pm 0.01_{stat}\pm 0.06_{sys}\pm 0.29_{norm} \right )\mu b$. The contribution of the quasifree processes (with the beam or target neutron being a spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of phase space. The remaining part of the cross section can be described by a partial wave decomposition indicating the significance of p-wave contributions in the final state.
Published: 2013

44. Investigation of the dd -> 3He n ��0 reaction with the FZ J��lich WASA-at-COSY facility

Author: COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hanhart, C., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Krapp, M., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Pluci��ski, P., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schmidt, A., Schadmand, S., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Tolba, T., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yuan, X., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: An exclusive measurement of the dd -> 3He n ��0 reaction was carried at a beam momentum of p = 1.2 GeV/c using the WASA-at-COSY facility. For the first time data on the total cross section as well as differential distributions were obtained. The data are described with a phenomenological approach based on a combination of a quasi-free model and a partial wave expansion for three-body reaction. The total cross section is found to be ��(tot) = (2.89 +- 0.01(stat) +- 0.06(sys) +- 0.29(norm)) ��b. The contribution of the quasi-free processes (with the neutron being target or beam spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of the phase space. The remaining part of the cross section can be described within a partial wave decomposition indicating the significance of p-wave contributions in the final state., 9 pages, 7 figures
Published: 2013
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45. Measurement of the $pn \rightarrow pp\pi ^{0}\pi ^{-}$ reaction in search for the recently observed resonance structure in $d\pi ^{0}\pi ^{0}$ and $d\pi ^{+}\pi ^{-}$ systems

Author: Adlarson, P., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Büscher, M., Calén, H., Ciepał, Izabela, Clement, H., Coderre, D., Czerwiński, Eryk, Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.-O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Hinterberger, F., Hodana, Małgorzata, Höistad, B., Jany, Anna, Jany, Benedykt, Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, Stanisław, Klaja, Joanna, Kleines, H., Kłos, B., Krapp, M., Krzemień, Wojciech, Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, Andrzej, Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Nandi, B. K., Ohm, H., Schätti - Ozerianska, Iryna, Perez del Rio, Elena, Piskunov, N. M., Pluciński, P., Podkopał, Paweł, Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, Andrzej, Redmer, C. F., Ritman, J., Roy, A., Rudy, Zbigniew, Sawant, S., Schmidt, A., Schadmand, S., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Tolba, T., Trzciński, A., Varma, R., Wagner, G. J., Węglorz, W., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yamamoto, A., Yuan, X., Zabierowski, J., Zheng, C., Zieliński, Marcin, Zipper, W., Złomańczuk, J., Żuprański, P., and Żurek, M.
Subjects: Nuclear Experiment
Abstract: Exclusive measurements of the quasifree $pn\rightarrow pp\pi ^{0}\pi ^{-}$ reaction have been performed by means of pd collisions at $T_{p}$= 1.2 GeV using the wide angle shower apparatus (WASA) detector setup at the cooler synchrotron COSY (Institut für Kernphysik, Jülich). Total and differential cross sections have been obtained covering the energy region $\sqrt{8}=\left ( 2.35-2.46 \right )$ GeV, which includes the region of the ABC effect and its associated resonance structure. No ABC effect, i.e., low-mass enhancement is found in the $\pi ^{0}\pi ^{-}$ -invariant mass spectrum, in agreement with the constraint from Bose statistics that the isovector pion pair can not be in relative s wave. At the upper end of the covered energy region t-channel processes for Roper, $\Delta \left ( 1600 \right )$ and $\Delta \Delta$ excitations provide a reasonable description of the data, but at low energies the measured cross sections are much larger than predicted by such processes. Adding a resonance amplitude for the resonance at m=2.37 GeV with $\Gamma$ =70 MeV and $I\left ( J^{P} \right )=0\left ( 3^{+} \right )$ observed recently in $pn\rightarrow d\pi ^{0}\pi ^{0}$ and $pn\rightarrow d\pi ^{+}\pi ^{-}$ reactions leads to an agreement with the data also at low energies.
Published: 2013

46. $\pi ^{0} \pi ^{0}$ production in proton–proton collisions at $T_{p} = 1.4$ GeV

Author: Adlarson, P., Adolph, C., Augustyniak, W., Bashkanov, M., Bednarski, Tomasz, Bergmann, F. S., Berłowski, M., Bhatt, H., Brinkmann, K.-T., Büscher, M., Calén, H., Clement, H., Coderre, D., Czerwiński, Eryk, Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Gullström, C.-O., Heijkenskjöld, L., Heimlich, J., Hejny, V., Hinterberger, F., Hodana, Małgorzata, Höistad, B., Jacewicz, M., Janusz, Michał, Jany, Anna, Jany, Benedykt, Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, Stanisław, Klaja, Joanna, Kleines, H., Kłos, B., Kren, F., Krzemień, Wojciech, Kulessa, P., Kupść, A., Lalwani, K., Lorentz, B., Magiera, Andrzej, Maier, R., Mariański, B., Marciniewski, P., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Nandi, B. K., Niedźwiecki, Szymon, Ohm, H., Passfeld, A., Pauly, C., Perez del Rio, Elena, Petukhov, Y., Piskunov, N., Pluciński, P., Podkopał, Paweł, Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Rausmann, T., Redmer, C. F., Ritman, J., Roy, A., Rudy, Zbigniew, Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Tolba, T., Trzciński, A., Varma, R., Vlasov, P., Wagner, G. J., Węglorz, W., Wiedner, U., Winnemöller, A., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieliński, Marcin, Zipper, W., Złomańczuk, J., and Żuprański, P.
Published: 2012

47. pi(0)pi(0) Production in proton-proton collisions at T-p=1.4 GeV The WASA-at-COSY Collaboration

Author: ADLARSON, P, ADOLPH, C, AUGUSTYNIAK, W, BASHKANOV, M, BEDNARSKI, T, BERGMANN, FS, BERLOWSKI, M, BHATT, H, BRINKMANN, KT, BUSCHER, M, CALEN, H, CLEMENT, H, CODERRE, D, CZERWINSKI, E, DOROSHKEVICH, E, ENGELS, R, ERVEN, W, EYRICH, W, FEDORETS, P, FOHL, K, FRANSSON, K, GOLDENBAUM, F, GOSLAWSKI, P, GRIGORYEV, K, GULLSTROM, CO, HEIJKENSKJOLD, L, HEIMLICH, J, HEJNY, V, HINTERBERGER, F, HODANA, M, HOISTAD, B, JACEWICZ, M, JANUSZ, M, JANY, A, JANY, BR, JARCZYK, L, JOHANSSON, T, KAMYS, B, KEMMERLING, G, KHAKIMOVA, O, KHOUKAZ, A, KISTRYN, S, KLAJA, J, KLEINES, H, KLOS, B, KREN, F, KRZEMIEN, W, KULESSA, P, KUPSC, A, LALWANI, K, LORENTZ, B, MAGIERA, A, MAIER, R, MARIANSKI, B, MARCINIEWSKI, P, MIKIRTYCHIANTS, M, MORSCH, HP, MOSKAL, P, NANDI, BK, NIEDZWIECKI, S, OHM, H, PASSFELD, A, PAULY, C, DEL RIO, EP, PETUKHOV, Y, PISKUNOV, N, PLUCINSKI, P, PODKOPAL, P, POVTOREYKO, A, PRASUHN, D, PRICKING, A, PYSZ, K, RAUSMANN, T, REDMER, CF, RITMAN, J, ROY, A, RUDY, Z, SAWANT, S, SCHADMAND, S, SCHMIDT, A, SEFZICK, T, SERDYUK, V, SHAH, N, SIEMASZKO, M, SKORODKO, T, SKURZOK, M, SMYRSKI, J, SOPOV, V, STASSEN, R, STEPANIAK, J, STERZENBACH, G, STOCKHORST, H, STROHER, H, SZCZUREK, A, TASCHNER, A, TOLBA, T, TRZCINSKI, A, VARMA, R, VLASOV, P, WAGNER, GJ, WEGLORZ, W, WIEDNER, U, WINNEMOLLER, A, WOLKE, M, WRONSKA, A, WUSTNER, P, WURM, P, YUAN, X, YUREV, L, ZABIEROWSKI, J, ZHENG, C, ZIELINSKI, MJ, ZIPPER, W, ZLOMANCZUK, J, and ZUPRANSKI, P
Subjects: Roper Resonance, Pion Production, Pp, Cross-Sections, 2-Pion Production, Excitation, Model
Abstract: The reaction pp -> pp pi(0)pi(0) has been investigated at a beam energy of 1.4 GeV using the WASA-at-COSY facility. The total cross section is found to be (324 +/- 21(systematic) +/- 58(normalization)) mu b. In order to study the production mechanism, differential kinematic distributions have been evaluated. The differential distributions indicate that both initial state protons are excited into intermediate Delta(1232) resonances, each decaying into a proton and a single pion, thereby producing the pion pair in the final state. No significant contribution of the Roper resonance N*(1440) via its decay into a proton and two pions is found. (C) 2011 Elsevier B.V. All rights reserved.
Published: 2012

48. Exclusive measurement of the $\eta \rightarrow \pi^{+} \pi^{-} \gamma$ decay

Author: Adlarson, P., Adolph, C., Augustyniak, W., Bardan, Wiktor, Bashkanov, M., Bednarski, Tomasz, Bergmann, F. S., Berłowski, M., Bhatt, H., Brinkmann, K.-T., Büscher, M., Calén, H., Clement, H., Coderre, D., Czerwiński, Eryk, Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Gullström, C.-O., Hanhart, C., Heijkenskjöld, L., Heimlich, J., Hejny, V., Hinterberger, F., Hodana, Małgorzata, Höistad, B., Jacewicz, M., Jany, Anna, Jany, Benedykt, Jarczyk, Lucjan, Johansson, T., Kamys, Bogusław, Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, Stanisław, Klaja, Joanna, Kleines, H., Kłos, B., Kren, F., Krzemień, Wojciech, Kulessa, P., Kupść, A., Lalwani, K., Leupold, S., Lorentz, B., Magiera, Andrzej, Maier, R., Mariański, B., Marciniewski, P., Meißner, U.-G., Mikirtychiants, M., Morsch, H.-P., Moskal, Paweł, Nandi, B. K., Niedźwiecki, Szymon, Ohm, H., Passfeld, A., Pauly, C., Perez del Rio, Elena, Petri, T., Petukhov, Y., Piskunov, N., Pluciński, P., Podkopał, Paweł, Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Pyszniak, Andrzej, Rausmann, T., Redmer, C. F., Ritman, J., Roy, A., Rudy, Zbigniew, Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, Magdalena, Smyrski, Jerzy, Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Stollenwerk, F., Ströher, H., Szczurek, A., Täschner, A., Terschlüsen, C., Tolba, T., Trzciński, A., Varma, R., Vlasov, P., Wagner, G. J., Węglorz, W., Winnemöller, A., Wirzba, A., Wolke, M., Wrońska, Aleksandra, Wüstner, P., Wurm, P., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieliński, Marcin, Zipper, W., Złomańczuk, J., and Żuprański, P.
Subjects: box anomaly, exclusive measurement, High Energy Physics::Experiment, $\eta$ meson, Nuclear Experiment
Abstract: An exclusive measurement of the decay $\eta \rightarrow \pi^{+} \pi^{-} \gamma$ has been performed at the WASA facility at COSY. The $\eta$ mesons were produced in the fusion reaction $pd \rightarrow ^{3}He X$ at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13 960 $\pm$ 140 events after background subtraction. The measured pion angular distribution is consistent with a relative p-wave of the two-pion system, whereas the measured photon energy spectrum was found at variance with the simplest gauge invariant matrix element of $\eta \rightarrow \pi^{+} \pi^{-} \gamma$. A parameterization of the data can be achieved by the additional inclusion of the empirical pion vector form factor multiplied by a first-order polynomial in the squared invariant mass of the $\pi^{+} \pi^{-}$ system.
Published: 2012

49. ��^0 ��^0 Production in Proton-Proton Collisions at Tp=1.4 GeV

Author: Adlarson, P., Adolph, C., Augustyniak, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Ber��owski, M., Bhatt, H., Brinkmann, K. --T., B��scher, M., Cal��n, H., Clement, H., Coderre, D., Czerwi��ski, E., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryevj, K., Gullstr��m, C. --O., Heijkenskj��ld, L., Heimlich, J., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jacewicz, M., Janusz, M., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Kren, F., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Lorentz, B., Machner, H., Magiera, A., Maier, R., Maria��ski, B., Marciniewski, P., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Nied��wiecki, S., Ohm, H., Passfeld, A., Pauly, C., del Rio, E. Perez, Petukhov, Y., Piskunov, N., Pluci��ski, P., Podkopa��, P., Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Rausmann, T., Redmer, C. F., Ritman, J., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Szczurek, A., T��schner, A., Tolba, T., Trzci��ski, A., Varma, R., Vlasov, P., Wagner, G. J., Weglorz, W., Wiedner, U., Winnem��ller, A., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., and Zupra��ski, P.
Subjects: High Energy Physics - Experiment (hep-ex), Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment
Abstract: The reaction pp->pppi0pi0 has been investigated at a beam energy of 1.4 GeV using the WASA-at-COSY facility. The total cross section is found to be (324 +- 21_systematic +- 58_normalization) mub. In order to to study the production mechanism, differential kinematical distributions have been evaluated. The differential distributions indicate that both initial state protons are excited into intermediate Delta(1232) resonances, each decaying into a proton and a single pion, thereby producing the pion pair in the final state. No significant contribution of the Roper resonance N*(1440) via its decay into a proton and two pions is found, Submitted to PLB
Published: 2011
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50. ABC effect and resonance structure in the double-pionic fusion to He-3

Author: Adlarson, Patrik, Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Bondar, A., Buescher, M., Calén, Hans, Ciepal, I., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, Kjell E., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstrlöm, Carl-Oscar, Hauenstein, F., Heijkenskjold, Lena, Hejny, V., Höistad, Bo, Huesken, N., Jarczyk, L., Johansson, Tord, Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, Anrezej, Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, Pavel, Marianski, B., Mikirtychiants, M., Morsch, H. -P, Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, Damian, Pysz, K., Pyszniak, Andrzej, Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Trzcinski, A., Varma, R., Wagner, G. J., Wolke, Magnus, Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zielinski, M. J., Zink, A., Zlomanczuk, Josef, Zupranski, P., Zurek, M., Adlarson, Patrik, Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Bondar, A., Buescher, M., Calén, Hans, Ciepal, I., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, Kjell E., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstrlöm, Carl-Oscar, Hauenstein, F., Heijkenskjold, Lena, Hejny, V., Höistad, Bo, Huesken, N., Jarczyk, L., Johansson, Tord, Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, Anrezej, Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, Pavel, Marianski, B., Mikirtychiants, M., Morsch, H. -P, Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, Damian, Pysz, K., Pyszniak, Andrzej, Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Trzcinski, A., Varma, R., Wagner, G. J., Wolke, Magnus, Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zielinski, M. J., Zink, A., Zlomanczuk, Josef, Zupranski, P., and Zurek, M.
Abstract: Exclusive and kinematically complete measurements of the double pionic fusion to He-3 have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the pi pi-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY (the cooler synchrotron at Forschungszentrum Julich). Similar to the observations in the basic pn -> d pi(0)pi(0) reaction and in the dd -> He-4 pi(0)pi(0) reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. Differential cross sections are well described by the hypothesis of d* resonance formation during the reaction process in addition to the conventional t-channel Delta Delta mechanism. The deduced d* resonance width can be understood from collision broadening due to Fermi motion of the nucleons in initial and final nuclei.
Published: 2015
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