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2. Backward single-pion production in the pd→3 He π0 reaction with WASA-at-COSY

Author

The WASA-at-COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bondar, A., Büscher, M., Calén, H., Ciepał, I., Clement, H., 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., Khatri, G., Khoukaz, A., Khreptak, 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., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., Perez del Rio, E., Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Schätti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Trzciński, A., Wolke, M., Wrońska, A., Wüstner, P., Yamamoto, A., Zabierowski, J., Zieliński, M. J., Złomańczuk, J., Żuprański, P., Żurek, M., and Wilkin, C.

Published
2018
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3. Measurement of the $\overrightarrow{n} p\rightarrow d\pi^{0}\pi^{0}$ reaction with polarized beam in the region of the 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., 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., Morsch, H. -P., Moskal, P., Ohm, H., Perez del Rio, E., Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Schätti-Ozerianska, I., 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., Wolke, M., Wrońska, A., Wüstner, P., Yamamoto, A., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., Żurek, M., and WASA-at-COSY Collaboration

Published
2016
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6. Cross section ratio and angular distributions of the reaction p + d → 3He + η 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., 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., 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., Żurek, M., and WASA-at-COSY Collaboration

Published
2014
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8. Differential cross sections for neutron-proton scattering in the region of the d∗(2380) dibaryon resonance

Author

Adlarson, P., Augustyniak, W., Clement, H., WASA-at-COSY Collaboration, Workman, R. L., Briscoe, W. J., Strakovsky, I. I., SAID Data Analysis Center, Švarc, A., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Bardan, W., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, Kirill, Gullström, C.--O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Bashkanov, M., Hodana, M., Höistad, B., Hüsken, N., Jany, A., Jany, B. R., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Bergmann, F. S., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Lersch, D., Berłowski, M., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, P., Ohm, H., Ozerianska, I., Bhatt, H., Perez del Rio, E., Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Büscher, M., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Calén, H., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Ciepał, I., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zink, A., Złomańczuk, J., and Zurek, M.

Subjects
+n+p+p%22">deuteron p --> n p p, partial wave analysis, Juelich COSY PS, dibaryon, pole [resonance], kinematics, beam [deuteron], scattering [p n], spectator [p], differential cross section, target [hydrogen], analyzing power, ddc:530, angular distribution, WASA, experimental results
Published
2020

9. Search for C violation in the decay η → π0e+e− with WASA-at-COSY

Author

WASA-at-COSY Collaboration, Adlarson, P., Ciepał, I., Clement, H., Czerwiński, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Augustyniak, W., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullström, C.-O., Heijkenskjöld, L., Hejny, V., Hüsken, N., Jarczyk, L., Johansson, T., Bardan, W., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krzemień, W., Bashkanov, M., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, Rudolf, Marciniewski, P., Mariański, B., Bergmann, F. S., Morsch, H.-P., Moskal, P., Ohm, H., Parol, W., Perez del Rio, E., Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Berłowski, M., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Schätti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Bondar, A., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Büscher, M., Ströher, Hans, Szczurek, A., Trzciński, A., Wolke, M., Wrońska, A., Wüstner, P., Yamamoto, A., Zabierowski, J., Zieliński, M. J., Złomańczuk, J., Calén, H., Żuprański, P., Żurek, M., and Wirzba, A.

Subjects
ddc:530
Published
2018

10. Measurement of the ω → π+π−π0 Dalitz plot distribution

Author

WASA-at-COSY Collaboration, Adlarson, P., Calén, H., Ciepal, I., Clement, H., Czerwinski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Augustyniak, W., Föhl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullström, C.-O., Heijkenskjold, L., Hejny, V., Hüsken, N., Jarczyk, L., Bardan, W., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., Bashkanov, M., Klos, B., Krzemien, W., Kulessa, P., Kupsc, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Bergmann, F. S., Marciniewski, P., Marianski, B., Morsch, H.-P., Moskal, P., Ohm, H., Perez del Rio, E., Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Berlowski, M., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Schätti-Ozerianska, I., Sefzick, T., Serdyuk, V., Bhatt, H., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Bondar, A., Stockhorst, H., Ströher, H., Szczurek, A., Trzcinski, A., Varma, R., Wolke, M., Wronska, A., Wüstner, P., Yamamoto, A., Zabierowski, J., Büscher, M., Zielinski, M. J., Zlomanczuk, J., Zupranski, P., Zurek, M., Kubis, B., and Leupold, S.

Subjects
density, omega(783), statistical [error], parametrization [Dalitz plot], Juelich COSY PS, mass [pi], final-state interaction, decay [meson], Uppsala CELSIUS Stor, phase shift, phase space, kinematics, ddc:530, pi+ pi, WASA, +pi%2B+pi-+pi0%22">omega(783) --> pi+ pi- pi0, experimental results
Published
2017

11. Isoscalar single-pion production in the region of Roper and d⁎(2380) resonances

Author

WASA-at-COSY Collaboration, Adlarson, P., Calén, H., Ciepał, I., Clement, H., Czerwiński, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Augustyniak, W., Föhl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, Kirill, Gullström, C.-O., Heijkenskjöld, L., Hejny, V., Hüsken, N., Jarczyk, L., Bardan, W., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Bashkanov, Mikhail, Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, Rudolf, Marciniewski, P., Bergmann, F. S., Mariański, B., Morsch, H.-P., Moskal, P., Ohm, H., Parol, W., Perez del Rio, E., Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Berłowski, M., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Schätti-Ozerianska, I., Sefzick, T., Serdyuk, V., Bhatt, H., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Bondar, A., Stockhorst, H., Ströher, H., Szczurek, A., Trzciński, A., Varma, R., Wolke, M., Wrońska, A., Wüstner, P., Yamamoto, A., Zabierowski, J., Büscher, M., Zieliński, M. J., Złomańczuk, J., Żuprański, P., and Żurek, M.

Subjects
production [pi], N(1440), p deuteron, Juelich COSY PS, Delta(1232), dibaryon, energy dependence, mass spectrum, isoscalar, differential cross section, excited state, ddc:530, angular distribution, branching ratio, WASA, particle identification, Monte Carlo, total cross section, experimental results
Published
2017

12. Measurement of the $��\to ��^+ ��^- ��^0$ Dalitz plot distribution

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., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Khreptak, O., 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., Morsch, H. -P., Moskal, P., Ohm, H., 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., Sch��tti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., ��urek, M., Kubis, B., and Leupold, S.

Subjects
FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Using the production reactions $pd\to {}^3\mbox{He}\,��$ and $pp\to pp��$, the Dalitz plot distribution for the $��\to ��^+ ��^- ��^0$ decay is studied with the WASA detector at COSY, based on a combined data sample of $ (4.408\pm 0.042) \times 10^4$ events. The Dalitz plot density is parametrised by a product of the $P$-wave phase space and a polynomial expansion in the normalised polar Dalitz plot variables $Z$ and $��$. For the first time, a deviation from pure $P$-wave phase space is observed with a significance of $4.1��$. The deviation is parametrised by a linear term $1+2��Z$, with $��$ determined to be $+0.147\pm0.036$, consistent with the expectations of $��$-meson-type final-state interactions of the $P$-wave pion pairs., 8 pages, 7 figures

Published
2016
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13. ABC effect and resonance structure in the double-pionic fusion to ${}^{3}\mathrm{He}$

Author

Adlarson, P., Augustyniak, W., Ciepał, I., Żuprański, P., Żurek, M., WASA-at-COSY Collaboration, Clement, H., Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Eyrich, W., Fedorets, P., Bardan, W., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.-O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Bashkanov, M., Höistad, B., Hüsken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Bergmann, F. S., Kleines, H., Kłos, B., Krzemień, W., Kulessa, P., Kupść, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Berłowski, M., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, P., Ohm, H., Ozerianska, I., Perez del Rio, E., Piskunov, N. M., Bhatt, H., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Bondar, A., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Büscher, M., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Calén, H., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieliński, M. J., Zink, A., and Złomańczuk, J.

Subjects
ddc:530, Nuclear Experiment
Abstract

Exclusive and kinematically complete measurements of the double pionic fusion to 3He have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the ππ-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→dπ0π0 reaction and in the dd→4Heπ0π0 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 ΔΔ 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

14. Neutron-Proton Scattering in the Context of the $d^*$(2380) Resonance

Author

Adlarson, P., Augustyniak, W., Clement, H., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., Żurek, M., Workman, R. L., Briscoe, W. J., Strakovsky, I. I., WASA-at-COSY Collaboration, Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Bardan, W., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.-O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Bashkanov, M., Hodana, M., Höistad, B., Hüsken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Bergmann, F. S., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Berłowski, M., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, P., Ohm, H., Bhatt, 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., Büscher, M., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Calén, H., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, Hans, Szczurek, A., Ciepał, I., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., and Yurev, L.

Subjects
Np Elastic-Scattering, Nuclear and High Energy Physics, Nucleon-Scattering, Partial wave analysis, Nuclear Theory, Hexaquark, Analyzing Power, FOS: Physical sciences, Context (language use), Double-Pionic Fusion, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Proton scattering, Neutron, ddc:530, Nuclear Experiment (nucl-ex), Nuclear Experiment, Partial-Wave Analysis, Physics, Elastic scattering, Scattering, Total Cross-Section, Resonance (chemistry), Intermediate Energies, Isospin Decomposition, Delta-Sigma-T, Spin Observables
Abstract

New data on quasifree polarized neutron-proton scattering in the region of the recently observed $d^{\ast}$ resonance structure are 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 $^{3}D_{3}−^{3}G_{3}$ coupled partial waves at (2380 $\pm$ 10−i40 $\pm$ 5) MeV—in accordance with the $d^{\ast}$ 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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15. 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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16. Energy Calibration for the Forward Detector at WASA-at-COSY

Author

Demmich, Kay and WASA-at-COSY Collaboration

Subjects
Physics, Particle physics, Meson, Scattering, QC1-999, Detector, Nuclear Theory, Context (language use), lcsh:QC1-999, Calibration, High statistic, ddc:530, High Energy Physics::Experiment, Statistical physics, Nuclear Experiment, Energy (signal processing), lcsh:Physics
Abstract

Studies on rare and forbidden decays of light mesons are one main aspect of the WASA-at-COSY physics program. In this context a large data set for η mesons has been produced in the proton-proton scattering in order to investigate the decay properties of this meson. This high statistic measurement allows, e.g., for the search for the C-parity violating reaction η → π 0 + e + + e − . This article presents a new calibration method which allows for an improved separation of the physical background by means of the missing mass method.

Published
2014

17. Search for the 4He-η bound state in dd → (4He-η)bound → 3Henπ 0 and dd → (4He-η)bound → 3Hepπ− reactions with the WASA-at-COSY facility

Author

Skurzok, M., Krzemien, W., Moskal, P., Wrońska, A., Guaraldo, C., Magiera, A., Stroeher, Hans, and WASA-at-COSY Collaboration

Subjects
ddc:530
Abstract

In November 2010, the search for the 4He-η bound state was performed with high statistics and high acceptance with the WASA-at-COSY facility using a ramped beam technique. The signature of η - mesic nuclei is searched for in the measured excitation functions for the two reaction channels: dd → 3Henπ0 and dd → 3Hepπ− near the η production threshold. This report includes the description of the experimental method and the status of the data analysis.

Published
2014

18. 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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19. 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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20. Double pion production in proton-proton interactions at Tp=1.4 GeV

Author

T. Tolba and null WASA-at-COSY Collaboration

Subjects
Nuclear physics, Cross section (geometry), Physics, Pion, Proton, Excited state, Nuclear Theory, Physics::Accelerator Physics, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, Excitation
Abstract

The total as well as the differential cross sections of the π0 π0 production in proton-proton interactions have been evaluated at Tp = 1.4 GeV using the WASA-at-COSY facility. The total cross section is found to be (324 ± 21systematic ± 58normalization) μb. The differential distributions indicate the mutual excitation of the initial protons into their first excited state, Δ(1232), which decays by emission of a proton and a pion. No significant contribution of the Roper N*(1440) via its decay into a proton and two pions is found.

Published
2012

21. Measurement of the eta->3pi0 Dalitz Plot Distribution with the WASA Detector at COSY

Author

COSY Collaboration

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

In the first production run of the WASA experiment at COSY, the eta decay into three neutral pions was measured in proton-proton interactions at a proton beam kinetic energy of 1.4 GeV. The Dalitz plot of the three pions was studied using 1.2e5 fully reconstructed events, and the quadratic slope parameter alpha was determined to be -0.027+/-0.008(stat)+/-0.005(syst). The result is consistent with previous measurements and further corroborates the importance of pion-pion final state interactions., 6 pages, 4 figures, elsarticle

Published
2008
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22. Study of light mesons with WASA-at-COSY

Author

Prencipe, Elisabetta and WASA-at-COSY Collaboration

Subjects
Physics, Particle physics, Hydrogen, Meson, QC1-999, Nuclear Theory, chemistry.chemical_element, Dalitz plot, Background level, Nuclear physics, Recoil, chemistry, Deuterium, ddc:530, High Energy Physics::Experiment, Symmetry breaking, Nuclear Experiment, Beam energy
Abstract

The WASA detector, operating at the COSY facility in Jülich (Germany) has been collecting data since 2007. The experiment allows to perform studies of light mesons, such as π0, η and ω rare decay processes, in order to perform precise measurements of branching ratios, determine Dalitz plot parameters, test symmetry and symmetry breaking, and evaluate transition form factors. In the experiments a proton or deuteron beam impinged on a pellet target of hydrogen or deuterium, which allows the reactions proton-proton (pp) or proton-deuteron (pd). A high-statistics sample of η mesons has been collected: in the reaction pd →3He η, 3×107η mesons were tagged at a beam energy of 1.0 GeV, while 5×108η mesons were produced in the reaction pp → ppη at 1.4 GeV. This corresponds to the production of 10 η/s and 100 η/s, respectively, for the two reaction processes. In the pp dataset a higher background level is found compared to the pd data set. In both cases, we identify the η mesons by means of the missing mass derived from the recoil particles. A kinematic fit largely rejects the background in our analysis. The advantage in using the pp dataset is that the production of η mesons is almost a factor of 10 higher than in the pd fusion to 3He. As we plan to measure the branching ratios of very rare processes, high statistics is needed. A summary of the recent activity on the study of light mesons with WASA-at-COSY here is given.

Published
2014

23. Double pion production in proton-proton interactions at Tp=1.4 GeV.

Author

Tolba, T. and WASA-at-COSY Collaboration

Subjects
*PROTON-proton interactions, *PION-pion interactions, *NUCLEAR cross sections, *DISTRIBUTION (Probability theory), *EXCITED state chemistry, *GAMMA decay
Abstract

The total as well as the differential cross sections of the π0 π0 production in proton-proton interactions have been evaluated at Tp = 1.4 GeV using the WASA-at-COSY facility. The total cross section is found to be (324 ± 21systematic ± 58normalization) μb. The differential distributions indicate the mutual excitation of the initial protons into their first excited state, Δ(1232), which decays by emission of a proton and a pion. No significant contribution of the Roper N*(1440) via its decay into a proton and two pions is found. [ABSTRACT FROM AUTHOR]

Published
2012
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