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1. Corrigendum to 'Isoscalar single-pion production in the region of Roper and d⁎(2380) resonances' [Phys. Lett. B 774 (2017) 599]

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, H. Bhatt, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C.-O. Gullström, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H.-P. Morsch, P. Moskal, H. Ohm, W. Parol, E. Perez del Rio, N.M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, K. Sitterberg, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, R. Varma, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M.J. Zieliński, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Physics, QC1-999
Published: 2020
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2. Search for η mesic 3He with the WASA-at-COSY facility in the pd→3He2γ and pd→3He6γ reactions

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, S.D. Bass, M. Berłowski, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, L. Heijkenskjöld, V. Hejny, S. Hirenzaki, L. Jarczyk, T. Johansson, B. Kamys, N.G. Kelkar, G. Kemmerling, A. Khreptak, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H.-P. Morsch, P. Moskal, H. Ohm, W. Parol, E. Perez del Rio, N.M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, J. Ritman, A. Roy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti–Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M.J. Zieliński, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Physics, QC1-999
Abstract: We report on the experimental search for the bound state of an η meson and He3 nucleus performed using the WASA-at-COSY detector setup. In order to search for the η-mesic nucleus decay, the pd→3He2γ and pd→3He6γ channels have been analysed. These reactions manifest the direct decay of the η meson bound in a He3 nucleus. This non-mesonic decay channel has been considered for the first time. When taking into account only statistical errors, the obtained excitation functions reveal a slight indication for a possible bound state signal corresponding to a 3He-η nucleus width Γ above 20 MeV and binding energy Bs between 0 and 15 MeV. However, the determined cross sections are consistent with zero in the range of the systematic uncertainty. Therefore, as final result we estimate only the upper limit for the cross section of the η-mesic He3 nucleus formation followed by the η meson decay which varies between 2 nb and 15 nb depending on possible bound state parameters. Keywords: η-mesic nuclei, η meson
Published: 2020
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3. Search for C violation in the decay η → π0e+e− with WASA-at-COSY

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C.-O. Gullström, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, A. Khreptak, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H.-P. Morsch, P. Moskal, H. Ohm, W. Parol, E. Perez del Rio, N.M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, K. Sitterberg, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M.J. Zieliński, J. Złomańczuk, P. Żuprański, M. Żurek, and A. Wirzba
Subjects: Physics, QC1-999
Abstract: We report on the search for the rare decay η→π0e+e− which is of interest to study C violation in the electromagnetic interaction which would indicate contributions from physics beyond the Standard Model, since the allowed decay via a two-photon intermediate state is strongly suppressed. The experiment has been performed using the WASA-at-COSY installation, located at the COSY accelerator of the Forschungszentrum Jülich, Germany. In total 3×107 events of the reaction pd→3Heη have been recorded at an excess energy of Q=59.8MeV. Based on this data set the C parity violating decay η→π0γ⁎→π0e+e− via a single-photon intermediate state has been searched for, resulting in new upper limits of Γ(η→π0e+e−)/Γ(η→π+π−π0)
Published: 2018
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4. Total and differential cross sections of η-production in proton–deuteron fusion for excess energies between Qη = 13 MeV and Qη = 81 MeV

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C.-O. Gullström, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, A. Khreptak, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H.-P. Morsch, P. Moskal, H. Ohm, W. Parol, E. Perez del Rio, N.M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, K. Sitterberg, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M.J. Zieliński, J. Złomańczuk, P. Żuprański, M. Żurek, and C. Wilkin
Subjects: Physics, QC1-999
Abstract: New data on both total and differential cross sections of the production of η mesons in proton–deuteron fusion to He3η in the excess energy region 13.6MeV≤Qη≤80.9MeV are presented. These data have been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum Jülich, using a proton beam at 15 different beam momenta between pp=1.60GeV/c and pp=1.74GeV/c. While significant structure of the total cross section is observed in the energy region 20MeV≲Qη≲60MeV, a previously reported sharp variation around Qη≈50MeV cannot be confirmed. Angular distributions show the typical forward-peaking that was noted earlier. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a wide interval. Keywords: Meson production, Proton–deuteron interactions, η meson
Published: 2018
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5. Importance of d-wave contributions in the charge symmetry breaking reaction dd→4Heπ0

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C.-O. Gullström, C. Hanhart, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H.-P. Morsch, P. Moskal, H. Ohm, W. Parol, E. Perez del Rio, N.M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, K. Sitterberg, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M.J. Zieliński, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Physics, QC1-999
Abstract: This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd→4Heπ0 using the WASA-at-COSY detector setup at an excess energy of Q=60MeV. The determined differential cross section can be parametrized as dσ/dΩ=a+bcos2⁡θ⁎, where θ⁎ is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a=(1.55±0.46(stat)+0.32−0.8(syst))pb/sr and b=(13.1±2.1(stat)−2.7+1.0(syst))pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the Δ isobar to the dd→4Heπ0 reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions. Keywords: Charge symmetry breaking, Deuteron–deuteron interactions, Pion production
Published: 2018
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6. Isoscalar single-pion production in the region of Roper and d⁎(2380) resonances

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, H. Bhatt, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C.-O. Gullström, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H.-P. Morsch, P. Moskal, H. Ohm, W. Parol, E. Perez del Rio, N.M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, K. Sitterberg, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, R. Varma, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M.J. Zieliński, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Single-pion production, Isoscalar part, Roper resonance, Dibaryon resonance, Physics, QC1-999
Abstract: Exclusive measurements of the quasi-free pn→ppπ− and pp→ppπ0 reactions have been performed by means of pd collisions at Tp=1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region Tp=0.95–1.3 GeV (s=2.3–2.46 GeV), which includes the regions of Δ(1232), N⁎(1440) and d⁎(2380) resonance excitations. From these measurements the isoscalar single-pion production has been extracted, for which data existed so far only below Tp=1 GeV. We observe a substantial increase of this cross section around 1 GeV, which can be related to the Roper resonance N⁎(1440), the strength of which shows up isolated from the Δ resonance in the isoscalar (Nπ)I=0 invariant-mass spectrum. No evidence for a decay of the dibaryon resonance d⁎(2380) into the isoscalar (NNπ)I=0 channel is found. An upper limit of 180 μb (90% C.L.) corresponding to a branching ratio of 9% has been deduced.
Published: 2017
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7. Measurement of the ω→π+π−π0 Dalitz plot distribution

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, H. Bhatt, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C.-O. Gullström, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, F.A. Khan, G. Khatri, A. Khoukaz, O. Khreptak, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H.-P. Morsch, P. Moskal, H. Ohm, E. Perez del Rio, N.M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, K. Sitterberg, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, R. Varma, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M.J. Zieliński, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Decays of other mesons, Meson–meson interactions, Light mesons, Physics, QC1-999
Abstract: Using the production reactions pd→He3ω and pp→ppω, the Dalitz plot distribution for the ω→π+π−π0 decay is studied with the WASA detector at COSY, based on a combined data sample of (4.408±0.042)×104 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 ϕ. For the first time, a deviation from pure P-wave phase space is observed with a significance of 4.1σ. The deviation is parametrised by a linear term 1+2αZ, with α determined to be +0.147±0.036, consistent with the expectations of ρ-meson-type final-state interactions of the P-wave pion pairs.
Published: 2017
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8. Search for an isospin I=3 dibaryon

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, H. Bhatt, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C.-O. Gullström, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, F.A. Khan, G. Khatri, A. Khoukaz, O. Khreptak, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, H.-P. Morsch, P. Moskal, H. Ohm, E. Perez del Rio, N.M. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schätti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, K. Sitterberg, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Trzciński, R. Varma, M. Wolke, A. Wrońska, P. Wüstner, A. Yamamoto, J. Zabierowski, M.J. Zieliński, A. Zink, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Physics, QC1-999
Abstract: Various theoretical calculations based on QCD or hadronic interactions predict that in addition to the recently observed dibaryon resonance d⁎(2380) with I(JP)=0(3+) there should also exist a dibaryon resonance with mirrored quantum numbers I(JP)=3(0+). We report here on a search for such a NN-decoupled state in data on the pp→ppπ+π+π−π− reaction. Since no clear-cut evidence has been found, we give upper limits for the production cross section of such a resonance in the mass range 2280–2500 MeV. Keywords: Dibaryons, Four-pion production
Published: 2016
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9. Measurement of the np→npπ0π0 reaction in search for the recently observed d⁎(2380) resonance

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, H. Bhatt, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, D. Coderre, E. Czerwiński, K. Demmich, E. Doroshkevich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, P. Goslawski, A. Goswami, K. Grigoryev, C.-O. Gullström, F. Hauenstein, L. Heijkenskjöld, V. Hejny, B. Höistad, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, F.A. Khan, A. Khoukaz, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, M. Mikirtychiants, H.-P. Morsch, P. Moskal, H. Ohm, I. Ozerianska, E. Perez del Rio, N.M. Piskunov, P. Podkopał, D. Prasuhn, A. Pricking, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, S. Sawant, S. Schadmand, T. Sefzick, V. Serdyuk, B. Shwartz, R. Siudak, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Täschner, A. Trzciński, R. Varma, G.J. Wagner, M. Wolke, A. Wrońska, P. Wüstner, P. Wurm, A. Yamamoto, J. Zabierowski, M.J. Zieliński, A. Zink, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Physics, QC1-999
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. Keywords: Two-pion production, ABC effect and resonance structure, Dibaryon resonance
Published: 2015
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10. Charge symmetry breaking in dd→He4π0 with WASA-at-COSY

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F.S. Bergmann, M. Berłowski, H. Bhatt, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, D. Coderre, E. Czerwiński, K. Demmich, E. Doroshkevich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, P. Goslawski, A. Goswami, K. Grigoryev, C.-O. Gullström, C. Hanhart, F. Hauenstein, L. Heijkenskjöld, V. Hejny, B. Höistad, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, F.A. Khan, A. Khoukaz, D.A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, M. Mikirtychiants, H.-P. Morsch, P. Moskal, H. Ohm, I. Ozerianska, E. Perez del Rio, N.M. Piskunov, P. Podkopał, D. Prasuhn, A. Pricking, D. Pszczel, K. Pysz, A. Pyszniak, C.F. Redmer, J. Ritman, A. Roy, Z. Rudy, S. Sawant, S. Schadmand, T. Sefzick, V. Serdyuk, B. Shwartz, R. Siudak, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Täschner, A. Trzciński, R. Varma, M. Wolke, A. Wrońska, P. Wüstner, P. Wurm, A. Yamamoto, L. Yurev, J. Zabierowski, M.J. Zieliński, A. Zink, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Physics, 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
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11. Differential cross sections for neutron-proton scattering in the region of the d*(2380) dibaryon resonance

Author: C.-O. Gullström, Markus Büscher, D. Pszczel, P. Podkopał, Pawel Marciniewski, S. Sawant, Paweł Moskal, R. Varma, P. Fedorets, I. Ozerianska, R. Maier, A. Švarc, J. Ritman, W. Eyrich, T. Sefzick, V. Serdyuk, P. Goslawski, E. Stephan, Jerzy Smyrski, P. Kulessa, N. Hüsken, B. Kamys, V. Hejny, K. Föhl, R. Engels, A. Pricking, P. Wüstner, H. Clement, Günter Kemmerling, A. Kupść, M. Mikirtychiants, A. Pyszniak, W. Augustyniak, D. Lersch, Izabela Ciepał, A. Goswami, Magdalena Skurzok, M. Bashkanov, Frank Goldenbaum, M. Krapp, K. Demmich, K. Pysz, B. Kłos, A. Magiera, Ferdous Khan, J. Zabierowski, Akira Yamamoto, Hans Stockhorst, M. Berłowski, A. Erven, H. Ströher, W. Erven, G. Sterzenbach, Antoni Szczurek, B. Lorentz, Rolf Stassen, Tord Johansson, K. Fransson, H. P. Morsch, Zbigniew Rudy, T. Skorodko, V. Sopov, H. Ohm, K. Grigoryev, A. Trzcinski, A. Khoukaz, S. Schadmand, P. Żuprański, A. Zink, Jozef Zlomanczuk, B. Mariański, R. Siudak, A. Täschner, I. I. Strakovsky, E. Doroshkevich, Aleksandra Wrońska, A. Jany, K. Lalwani, Eryk Czerwiński, Hans Calén, Stanisław Kistryn, W. Bardan, W. J. Briscoe, E. Perez del Rio, Ankhi Roy, Wojciech Krzemien, M. Hodana, J. Stepaniak, C. F. Redmer, F. S. Bergmann, Magnus Wolke, Harald Kleines, Di. Kirillov, F. Hauenstein, Lena Heijkenskjöld, D. Prasuhn, P. Wurm, Patrik Adlarson, Bo Höistad, D. Coderre, L. Yurev, Benedykt R. Jany, Himani Bhatt, N.M. Piskunov, Ron L. Workman, M. Żurek, and Marcin Zieliński
Subjects: Physics, Nuclear physics, Range (particle radiation), Hydrogen, chemistry, Deuterium, Scattering, chemistry.chemical_element, Neutron, Nuclear Experiment, Resonance (particle physics), Beam (structure), Differential (mathematics)
Abstract: Differential cross sections have been extracted from exclusive and kinematically complete high-statistics measurements of quasifree polarized np scattering performed in the energy region of the d*(2380) dibaryon resonance covering the range of beam energies Tn=0.98−1.29 GeV (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+pspectator. In this way the np differential cross section σ(Θ) was measured over a large angular range. The obtained angular distributions complement the corresponding analyzing power Ay(Θ) measurements published previously. A SAID partial-wave analysis incorporating the new data strengthens the finding of a resonance pole in the coupled D33-G33 waves.
Published: 2020

12. Three-nucleon dynamics in dp breakup collisions using the WASA detector at COSY-Jülich

Author: Jozef Zlomanczuk, P. Kulessa, K. Pysz, A. Kupść, Ankhi Roy, J. Zabierowski, A. Trzcinski, Antoni Szczurek, B. Kłos, Aleksandra Wrońska, E. Perez del Rio, A. Deltuva, T. Sefzick, R. Maier, D. Lersch, W. Augustyniak, D. Pszczel, Frank Goldenbaum, S. Schadmand, Eryk Czerwiński, K. Lalwani, S. Sawant, H. P. Morsch, M. Żurek, Harald Kleines, W. Erven, A. Kozela, Jacek Golak, Oleksandr Rundel, Wojciech Krzemien, B. Kamys, P. Żuprański, R. Skibiński, Marcin Zieliński, R. Engels, P. Wüstner, B. Shwartz, J. Stepaniak, Paweł Moskal, W. Eyrich, E. Stephan, A. Magiera, F. S. Bergmann, A. Wilczek, Magnus Wolke, N. Hüsken, V. Sopov, W. Bardan, B. Mariański, M. Berłowski, Patrik Adlarson, Magdalena Skurzok, Hans Calén, Akira Yamamoto, M. Bashkanov, T. Skorodko, Pawel Marciniewski, A. Erven, H. Ströher, K. Fransson, K. Demmich, J. Ritman, Tord Johansson, Henryk Witała, V. Serdyuk, Jerzy Smyrski, K. Grigoryev, L. Jarczyk, A. Khoukaz, Izabela Ciepał, A. Goswami, Hans Stockhorst, Rolf Stassen, G. Sterzenbach, B. Lorentz, Stanisław Kistryn, Lena Heijkenskjöld, D. Prasuhn, V. Hejny, K. Föhl, Günter Kemmerling, Markus Büscher, I. Skwira-Chalot, P. Fedorets, Wiktor Parol, N.M. Piskunov, H. Clement, Di. Kirillov, A.E. Bondar, and Aleksander Khreptak
Subjects: Physics, Scattering cross-section, дейтроны, нуклоны, 010308 nuclear & particles physics, Dynamics (mechanics), Detector, Nuclear Theory, Breakup, 01 natural sciences, dp-развал, Nuclear physics, Deuterium, 0103 physical sciences, Physics::Accelerator Physics, ddc:530, протоны, 010306 general physics, Nucleon, Nuclear Experiment, Beam energy
Abstract: The differential cross section for the 1H(d,pp)n breakup reaction at deuteron beam energy of 340 MeV has been measured with the use of the WASA detector at COSY-Jülich. The set of proton-proton coincidences registered at the Forward Detector has been analyzed on a dense grid of kinematic variables, giving in total around 5600 data points. The cross-section data are compared to theoretical predictions based on the state-of-the-art nucleon-nucleon potentials, combined with a three-nucleon force or the Coulomb interaction or carried out in a relativistic regime.
Published: 2020

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

Author: B.A. Shwartz, A. Khoukaz, B. Kamys, D. Lersch, Frank Goldenbaum, P. Wüstner, A. Trzcinski, Oleksandr Rundel, E. Stephan, W. Bardan, Jozef Zlomanczuk, Di. Kirillov, P. Adlarson, Paweł Moskal, S. Sawant, H. Clement, P. Żuprański, T. Sefzick, J. Zabierowski, Magdalena Skurzok, A. Magiera, S. Schadmand, W. Eyrich, Aleksandra Wrońska, Antoni Szczurek, E. Perez del Rio, James Ritman, A. Khreptak, D. Pszczel, N. Hüsken, Pawel Marciniewski, Günter Kemmerling, J. Stepaniak, Hans Calén, M. Bashkanov, H. Ohm, A. Kuzmin, M. Żurek, M. Berłowski, Wiktor Parol, A. Pyszniak, W. Augustyniak, A. Erven, I. Schätti-Ozerianska, G. Khatri, K. Sitterberg, V. Serdyuk, Ankhi Roy, Jerzy Smyrski, Stanisław Kistryn, V. Hejny, T. Johansson, Kjell Fransson, V. Sopov, Izabela Ciepał, Akira Yamamoto, T. Skorodko, A. Kupść, A.E. Bondar, R. Maier, G. Sterzenbach, B. Lorentz, W. Erven, K. Pysz, P. Fedorets, B. Kłos, Andreas Wirzba, Lena Heijkenskjöld, H. Ströher, Hans Stockhorst, D. Prasuhn, N.M. Piskunov, Ralf Engels, Rolf Stassen, P. Kulessa, H. P. Morsch, Wojciech Krzemien, K. Lalwani, F. S. Bergmann, Magnus Wolke, Zbigniew Rudy, Eryk Czerwiński, Harald Kleines, K. Grigoryev, L. Jarczyk, A. Goswami, K. Demmich, Marcin Zieliński, B. Mariański, K. Föhl, C.-O. Gullström, and Markus Büscher
Subjects: Nuclear and High Energy Physics, Meson, Hadron, Elementary particle, cząstki elementarne, 01 natural sciences, Standard Model, fizyka jądrowa, бозоны, Pion, 0103 physical sciences, Intermediate state, detektor WASA, ddc:530, Nuclear Experiment, 010306 general physics, Boson, Physics, 010308 nuclear & particles physics, фотоны, распад, respiratory system, lcsh:QC1-999, 3. Good health, детекторы, cardiovascular system, мезоны, Physical chemistry, High Energy Physics::Experiment, Radioactive decay, lcsh:Physics, circulatory and respiratory physiology
Abstract: We report on the search for the rare decay η → π 0 e + e − which is of interest to study C violation in the electromagnetic interaction which would indicate contributions from physics beyond the Standard Model, since the allowed decay via a two-photon intermediate state is strongly suppressed. The experiment has been performed using the WASA-at-COSY installation, located at the COSY accelerator of the Forschungszentrum Julich, Germany. In total 3 × 10 7 events of the reaction p d → 3 He η have been recorded at an excess energy of Q = 59.8 MeV . Based on this data set the C parity violating decay η → π 0 γ ⁎ → π 0 e + e − via a single-photon intermediate state has been searched for, resulting in new upper limits of Γ ( η → π 0 e + e − ) / Γ ( η → π + π − π 0 ) 3.28 × 10 − 5 and Γ ( η → π 0 e + e − ) / Γ ( η → all ) 7.5 × 10 − 6 ( CL = 90 % ), respectively.
Published: 2018

14. Search for η-mesic He4 in the dd→He3nπ0 and dd→He3pπ− reactions with the WASA-at-COSY facility

Author: M. Bashkanov, A. Erven, K. Sitterberg, B. Lorentz, Frank Goldenbaum, A. Trzcinski, D. Lersch, H. Ströher, C.-O. Gullström, Markus Büscher, Jozef Zlomanczuk, Günter Kemmerling, A.E. Bondar, K. Grigoryev, H. Bhatt, R. Stassen, H. P. Morsch, Marcin Zieliński, A. Kuzmin, P. Adlarson, L. Jarczyk, T. Johansson, Rudolf Maier, H. Ohm, W. Eyrich, Aleksandra Wrońska, E. Perez del Rio, M. Berłowski, J. Zabierowski, A. Magiera, G. Sterzenbach, A. Goswami, P. Żuprański, B. Kłos, Di. Kirillov, K. Demmich, N. Hüsken, B. Mariański, P. Kulessa, V. Sopov, A. Pyszniak, W. Augustyniak, Zbigniew Rudy, Antoni Szczurek, K. Pysz, P. Fedorets, H. Clement, W. Erven, D. Pszczel, Hans Calén, Izabela Ciepał, O. Khreptak, T. Skorodko, Eryk Czerwiński, F. S. Bergmann, Magnus Wolke, S. Schadmand, T. Sefzick, Oleksandr Rundel, Magdalena Skurzok, Kjell Fransson, I. Schätti-Ozerianska, Harald Kleines, H. Stockhorst, N. G. Kelkar, K. Föhl, Stanisław Kistryn, J. Stepaniak, E. Stephan, W. Bardan, N.M. Piskunov, M. Żurek, Paweł Moskal, Pawel Marciniewski, Lena Heijkenskjöld, K. Lalwani, Wojciech Krzemien, G. Khatri, S. Sawant, Akira Yamamoto, A. Kupść, R. Engels, D. Prasuhn, J. Ritman, Ankhi Roy, V. Serdyuk, Jerzy Smyrski, B. Kamys, P. Wüstner, R. Varma, V. Hejny, B.A. Shwartz, and A. Khoukaz
Subjects: Excitation function, Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Scattering, 01 natural sciences, Momentum, Deuterium, Isospin, 0103 physical sciences, Bound state, Atomic physics, 010306 general physics, Nucleon, Excitation
Abstract: The search for He 4 - η bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the d d → He 3 n π 0 and d d → He 3 p π − processes. The deuteron beam momentum was varied continuously between 2.127 GeV/c and 2.422 GeV/c, corresponding to the excess energy for the d d → He 4 η reaction ranging from Q = − 70 MeV to Q = 30 MeV . The luminosity was determined based on the d d → He 3 n reaction and the quasi-free proton–proton scattering via d d → p p n s p e c t a t o r n s p e c t a t o r reactions. The excitation functions, determined independently for the measured reactions, do not reveal a structure which could be interpreted as a narrow mesic nucleus. Therefore, the upper limits of the total cross sections for the bound state production and decay in d d → ( He 4 - η ) b o u n d → He 3 n π 0 and d d → ( He 4 - η ) b o u n d → He 3 p π − processes were determined taking into account the isospin relation between the both of the considered channels. The results of the analysis depend on the assumptions of the N ⁎ (1535) momentum distribution in the anticipated mesic- He 4 . Assuming, as in the previous works, that this is identical with the distribution of nucleons bound with 20 MeV in He 4 , we determined that (for the mesic bound state width in the range from 5 MeV to 50 MeV) the upper limits at 90% confidence level are about 3 nb and about 6 nb for n π 0 and p π − channels, respectively. However, based on the recent theoretical findings of the N ⁎ (1535) momentum distribution in the N ⁎ - He 3 nucleus bound by 3.6 MeV, we find that the WASA-at-COSY detector acceptance decreases and hence the corresponding upper limits are 5 nb and 10 nb for n π 0 and p π − channels respectively.
Published: 2017

15. Examination of the production of an isotensor dibaryon in the pp→ppπ+π− reaction

Author: Zbigniew Rudy, Akira Yamamoto, O. Khreptak, A. Khoukaz, Eryk Czerwiński, B. Kamys, P. Żuprański, K. Fransson, Harald Kleines, Oleksandr Rundel, R. Engels, D. Lersch, P. Wüstner, H. P. Morsch, H. Clement, Hans Calén, E. Stephan, Jozef Zlomanczuk, T. Sefzick, W. Erven, A.E. Bondar, W. Eyrich, Wiktor Parol, Markus Büscher, M. Bashkanov, N. Hüsken, Pawel Marciniewski, A. Erven, Paweł Moskal, K. Pysz, M. Berłowski, D. Pszczel, A. Magiera, P. Fedorets, J. Ritman, T. Skorodko, Izabela Ciepał, A. Goswami, Di. Kirillov, B. Mariański, V. Serdyuk, H. Ströher, Stanisław Kistryn, P. Kulessa, Jerzy Smyrski, V. Hejny, K. Föhl, I. Schätti-Ozerianska, A. Trzcinski, S. Schadmand, Hans Stockhorst, B. Shwartz, J. Stepaniak, N.M. Piskunov, Lena Heijkenskjöld, W. Augustyniak, D. Prasuhn, V. Sopov, Rolf Stassen, G. Sterzenbach, B. Lorentz, Wojciech Krzemien, W. Bardan, Günter Kemmerling, J. Zabierowski, Antoni Szczurek, Aleksandra Wrońska, Ankhi Roy, E. Perez del Rio, M. Żurek, Marcin Zieliński, R. Maier, K. Grigoryev, L. Jarczyk, S. Sawant, F. S. Bergmann, Magnus Wolke, K. Demmich, K. Lalwani, A. Kupść, T. Johansson, B. Kłos, P. Adlarson, Magdalena Skurzok, H. Ohm, and Frank Goldenbaum
Subjects: Nuclear physics, Physics, Cross section (physics), Pion, Meson, 010308 nuclear & particles physics, Isospin, 0103 physical sciences, 010306 general physics, 7. Clean energy, 01 natural sciences, Resonance (particle physics)
Abstract: The quasifree pp → ppπ+π− reaction has been measured by means of pd collisions at Tp = 1.2 GeV using the WASA detector setup at COSY enabling exclusive and kinematically complete measurements. Total and differential cross sections have been extracted for the energy region Tp = 1.08–1.36 GeV (√s = 2.35–2.46 GeV) covering thus the regions of N∗(1440) and (1232)(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange as well as isospin relations based on the pp → ppπ0π0 data underpredict substantially the measured total cross section. The calculations are also at variance with specific experimental differential cross sections. An isotensor N dibaryon resonance with I (J P ) = 2(1+) produced associatedly with a pion is able to overcome these deficiencies. Such a dibaryon was predicted by Dyson and Xuong [Phys. Rev. Lett. 13, 815 (1964)] and more recently calculated by A. Gal and H. Garcilazo [Nucl. Phys. A 928, 73 (2014)].
Published: 2019

16. Search for an isospin I= 3 dibaryon

Author: A.E. Bondar, Izabela Ciepał, O. Khreptak, Hans Stockhorst, Pawel Marciniewski, Rolf Stassen, Frank Goldenbaum, M. Berłowski, A. Magiera, J. Stepaniak, Jozef Zlomanczuk, J. Ritman, T. Skorodko, W. Erven, Di. Kirillov, Oleksandr Rundel, A. Zink, Paweł Moskal, V. Serdyuk, H. Bhatt, W. Eyrich, P. Kulessa, H. P. Morsch, T. Sefzick, Jerzy Smyrski, B. Kamys, P. Żuprański, P. Wüstner, D. Lersch, E. Stephan, M. Żurek, C.-O. Gullström, N. Hüsken, Markus Büscher, Günter Kemmerling, S. Schadmand, Zbigniew Rudy, N.M. Piskunov, A. Pyszniak, W. Augustyniak, A. Kuzmin, Hans Calén, M. Bashkanov, Eryk Czerwiński, K. Pysz, P. Fedorets, H. Clement, G. Khatri, Ferdous Khan, Kjell Fransson, Rudolf Maier, V. Hejny, A. Erven, Stanisław Kistryn, Harald Kleines, Akira Yamamoto, A. Kupść, K. Sitterberg, W. Bardan, Lena Heijkenskjöld, D. Prasuhn, B.A. Shwartz, A. Khoukaz, R. Varma, G. Sterzenbach, B. Lorentz, Ralf Engels, J. Zabierowski, Ankhi Roy, K. Föhl, Antoni Szczurek, H. Ströher, A. Trzcinski, Wojciech Krzemien, V. Sopov, D. Pszczel, I. Schätti-Ozerianska, Marcin Zieliński, P. Adlarson, H. Ohm, B. Mariański, Aleksandra Wrońska, E. Perez del Rio, Magdalena Skurzok, F. S. Bergmann, Magnus Wolke, K. Grigoryev, L. Jarczyk, A. Goswami, K. Demmich, T. Johansson, B. Kłos, K. Lalwani, and S. Sawant
Subjects: Nuclear and High Energy Physics, Particle physics, Pion-Production, Gev/C, Nuclear Theory, Hadron, FOS: Physical sciences, 01 natural sciences, Pp Collisions, High Energy Physics - Experiment, Subatomär fysik, Nuclear physics, High Energy Physics - Experiment (hep-ex), dibaryons, Subatomic Physics, 0103 physical sciences, ddc:530, Nuclear Experiment (nucl-ex), Nuclear Experiment, 010306 general physics, Proton-Proton Interactions, Physics, Quantum chromodynamics, States, Decomposition, Four-pion production, Dibaryons, 010308 nuclear & particles physics, Resonance, Quantum number, lcsh:QC1-999, Energies, Delta, Resonances, Isospin, four-pion production, 24 Gev-C, Beam energy, lcsh:Physics
Abstract: Various theoretical calculations based on QCD or hadronic interactions predict that in addition to the recently observed dibaryon resonance d⁎(2380) with I(JP)=0(3+) there should also exist a dibaryon resonance with mirrored quantum numbers I(JP)=3(0+). We report here on a search for such a NN-decoupled state in data on the pp→ppπ+π+π−π− reaction. Since no clear-cut evidence has been found, we give upper limits for the production cross section of such a resonance in the mass range 2280–2500 MeV., This work has been supported by DFG (CL 214/3-1), STFC (ST/L00478X/1) and by the Polish National Science Center through grants Nos. DEC-2013/11/N/ST2/04152 and 2011/03/B/ST2/01847
Published: 2016

17. Corrigendum to 'Isoscalar single-pion production in the region of Roper and d⁎(2380) resonances' [Phys. Lett. B 774 (2017) 599]

Author: A. Khoukaz, K. Grigoryev, P. Fedorets, P. Żuprański, P. Wüstner, R. Stassen, W. Eyrich, Wiktor Parol, B. Kamys, A. Bondar, Hans Calén, C.-O. Gullström, Aleksandra Wrońska, H. Clement, E. Perez del Rio, Kjell Fransson, A. Trzciński, M. Bashkanov, A. Pyszniak, W. Augustyniak, Izabela Ciepał, Magnus Wolke, V. Serdyuk, A. Magiera, Zbigniew Rudy, A. Yamamoto, H. Kleines, A. Kupść, Eryk Czerwiński, H.-P. Morsch, Pawel Marciniewski, A. Roy, Marcin Zieliński, H. Ohm, H. Stockhorst, K. Pysz, L. Jarczyk, G. Sterzenbach, P. Kulessa, Stanisław Kistryn, N.M. Piskunov, B. Shwartz, K. Sitterberg, B. Lorentz, K. Lalwani, K. Demmich, R. Varma, J. Ritman, W. Bardan, Lena Heijkenskjöld, G. Khatri, Paweł Moskal, D.A. Kirillov, Jerzy Smyrski, T. Sefzick, M. Büscher, F. Goldenbaum, G. Kemmerling, R. Maier, T. Johansson, B. Kłos, A. Kuzmin, D. Prasuhn, S. Sawant, F.S. Bergmann, A. Goswami, T. Skorodko, V. Hejny, N. Hüsken, J. Stepaniak, Himani Bhatt, S. Schadmand, D. Lersch, B. Mariański, V. Sopov, P. Adlarson, Oleksandr Rundel, Magdalena Skurzok, M. Berłowski, D. Pszczel, H. Ströher, R. Engels, I. Schätti-Ozerianska, W. Erven, J. Zabierowski, Wojciech Krzemien, E. Stephan, A. Szczurek, K. Föhl, A. Erven, M. Żurek, O. Khreptak, and Jozef Zlomanczuk
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Pion, Isoscalar, ddc:530, lcsh:Physics, lcsh:QC1-999
Published: 2020

18. Search for η mesic 3He with the WASA-at-COSY facility in the pd→3He2γ and pd→3He6γ reactions

Author: Jozef Zlomanczuk, A. Trzcinski, W. Bardan, A. Magiera, V. Hejny, R. Maier, S. Sawant, James Ritman, Aleksandra Wrońska, E. Perez del Rio, B. Kamys, K. Grigoryev, Izabela Ciepał, D. Pszczel, B. Mariański, P. Wüstner, B.A. Shwartz, A.E. Bondar, T. Sefzick, Akira Yamamoto, A. Kupść, Hans Stockhorst, I. Schätti–Ozerianska, V. Sopov, D. Lersch, Rolf Stassen, T. Johansson, L. Jarczyk, B. Kłos, G. Sterzenbach, B. Lorentz, Oleksandr Rundel, M. Żurek, S. Schadmand, Paweł Moskal, A. Goswami, Marcin Zieliński, E. Stephan, Wiktor Parol, Pawel Marciniewski, Ralf Engels, Di. Kirillov, P. Kulessa, W. Erven, H. Clement, Wojciech Krzemien, Satoru Hirenzaki, V. Serdyuk, M. Berłowski, Günter Kemmerling, Jerzy Smyrski, Stanisław Kistryn, W. Augustyniak, K. Föhl, Ankhi Roy, A. Khreptak, T. Skorodko, Lena Heijkenskjöld, D. Prasuhn, W. Eyrich, Magnus Wolke, Markus Büscher, J. Zabierowski, M. Bashkanov, N.M. Piskunov, Antoni Szczurek, N. G. Kelkar, A. Erven, H. Ströher, Eryk Czerwiński, Harald Kleines, K. Lalwani, Frank Goldenbaum, Steven D. Bass, P. Żuprański, Hans Calén, Kjell Fransson, K. Pysz, P. Fedorets, J. Stepaniak, H. P. Morsch, H. Ohm, P. Adlarson, and Magdalena Skurzok
Subjects: Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Nuclear Theory, Eta meson, Detector, 01 natural sciences, Nuclear physics, medicine.anatomical_structure, 0103 physical sciences, Bound state, medicine, Order (group theory), High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleus
Abstract: We report on the experimental search for the bound state of an eta meson and He-3 nucleus performed using the WASA-at-COSY detector setup. In order to search for the eta-mesic nucleus decay, the pd ...
Published: 2020

19. Backward single-pion production in the $ pd\rightarrow {}^{3}\mathrm{He} \pi^{0}$ p d → 3 He π 0 reaction with WASA-at-COSY

Author: Günter Kemmerling, Izabela Ciepał, A. Trzcinski, Aleksandra Wrońska, E. Perez del Rio, Hans Calén, Hans Stockhorst, W. Eyrich, Wojciech Krzemien, R. Maier, H. Ohm, D. Lersch, Rolf Stassen, N. Hüsken, Kjell Fransson, Jozef Zlomanczuk, K. Lalwani, G. Sterzenbach, P. Kulessa, Stanisław Kistryn, B. Lorentz, C. Wilkin, H. Clement, Lena Heijkenskjöld, Pawel Marciniewski, Ralf Engels, D. Prasuhn, Frank Goldenbaum, Oleksandr Rundel, B. Mariański, Paweł Moskal, B.A. Shwartz, A. Khoukaz, F. S. Bergmann, J. Zabierowski, Magnus Wolke, Magdalena Skurzok, N.M. Piskunov, T. Johansson, W. Erven, E. Stephan, H. Ströher, K. Föhl, A. Magiera, Antoni Szczurek, A. Kuzmin, Wiktor Parol, P. Żuprański, B. Kłos, D. Pszczel, James Ritman, S. Sawant, I. Schätti-Ozerianska, V. Serdyuk, A. Pyszniak, W. Augustyniak, V. Sopov, Jerzy Smyrski, K. Grigoryev, C.-O. Gullström, Markus Büscher, B. Kamys, M. Bashkanov, V. Hejny, Akira Yamamoto, P. Wüstner, A. Kupść, A. Erven, Marcin Zieliński, L. Jarczyk, W. Bardan, K. Sitterberg, P. Adlarson, A. Goswami, K. Demmich, S. Schadmand, G. Khatri, M. Berłowski, Ankhi Roy, T. Skorodko, T. Sefzick, Zbigniew Rudy, M. Żurek, Eryk Czerwiński, Harald Kleines, K. Pysz, P. Fedorets, J. Stepaniak, H. P. Morsch, Di. Kirillov, A. Khreptak, and A.E. Bondar
Subjects: Physics, Nuclear reaction, Nuclear and High Energy Physics, Meson, Proton, 010308 nuclear & particles physics, Hadron, Elementary particle, 01 natural sciences, 7. Clean energy, Nuclear physics, Pion, 0103 physical sciences, Production (computer science), Nuclear Experiment, 010306 general physics, Isotopes of helium
Abstract: New data on the production of single neutral pions in the $ pd\rightarrow {}^{3}\mathrm{He} \pi^{0}$ reaction are presented. For fifteen proton beam momenta between $ p_{p}=1.60$ GeV/c and $ p_{p}=1.74$ GeV/c, differential cross sections are determined over a large fraction of the backward hemisphere. Since the only previous systematic measurements of single-pion production at these energies were made in collinear kinematics, the present work constitutes a significant extension of the current knowledge on this reaction. Even this far above the production threshold, significant changes are found in the behaviour of the angular distributions over small intervals in beam momentum.
Published: 2018

20. Isotensor Dibaryon in the pp→ppπ+π− Reaction?

Author: A. Magiera, Stanisław Kistryn, O. Khreptak, H. Clement, A. Bondar, B. Shwartz, J. Stepaniak, Lena Heijkenskjöld, D. Prasuhn, K. Lalwani, H. Ohm, D. Lersch, W. Erven, T. Johansson, Jozef Zlomanczuk, H. P. Morsch, G. Sterzenbach, B. Lorentz, Ralf Engels, Pawel Marciniewski, B. Kłos, Wiktor Parol, A. Khoukaz, D. Pszczel, K. Föhl, H. Ströher, Izabela Ciepał, F. S. Bergmann, K. Pysz, P. Fedorets, W. Augustyniak, J. Ritman, V. Serdyuk, S. Sawant, Frank Goldenbaum, Jerzy Smyrski, Aleksandra Wrońska, E. Perez del Rio, Hans Stockhorst, Magnus Wolke, V. Hejny, M. Bashkanov, I. Schätti-Ozerianska, T. Sefzick, S. Schadmand, Akira Yamamoto, A. Kupść, A. Trzcinski, Marcin Zieliński, Rolf Stassen, A. Erven, Di. Kirillov, P. Żuprański, B. Kamys, Markus Büscher, W. Eyrich, Günter Kemmerling, P. Wüstner, N. Hüsken, Hans Calén, P. Adlarson, K. Grigoryev, Kjell Fransson, Magdalena Skurzok, M. Żurek, Paweł Moskal, L. Jarczyk, M. Berłowski, Wojciech Krzemien, R. Maier, A. Goswami, K. Demmich, T. Skorodko, B. Mariański, J. Zabierowski, Antoni Szczurek, Zbigniew Rudy, Eryk Czerwiński, Harald Kleines, V. Sopov, W. Bardan, Oleksandr Rundel, E. Stephan, P. Kulessa, N.M. Piskunov, and Ankhi Roy
Subjects: Nuclear physics, Physics, Cross section (physics), Pion, Meson, 010308 nuclear & particles physics, Excited state, 0103 physical sciences, General Physics and Astronomy, 010306 general physics, 01 natural sciences, Resonance (particle physics), Energy (signal processing)
Abstract: Exclusive measurements of the quasifree pp→ppπ^{+}π^{-} reaction have been carried out at WASA@COSY by means of pd collisions at T_{p}=1.2 GeV. Total and differential cross sections have been extracted covering the energy region T_{p}=1.08-1.36 GeV, which is the region of N^{*}(1440) and Δ(1232)Δ(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor ΔN dibaryon resonance with I(J^{P})=2(1^{+}) produced associatedly with a pion is able to overcome these deficiencies.
Published: 2018

21. Importance of -wave Contributions in the Charge Symmetry Breaking Reaction

Author: D. Lersch, O. Khreptak, M. Bashkanov, K. Grigoryev, A. Erven, K. Sitterberg, K. Föhl, Izabela Ciepał, H. Ströher, Oleksandr Rundel, A. Magiera, V. Sopov, T. Johansson, B. Kłos, Jozef Zlomanczuk, A. Trzcinski, L. Jarczyk, B.A. Shwartz, A. Khoukaz, Hans Stockhorst, G. Khatri, E. Stephan, Rolf Stassen, G. Sterzenbach, Marcin Zieliński, S. Sawant, B. Lorentz, N.M. Piskunov, A. Kuzmin, A. Goswami, J. Zabierowski, K. Demmich, C.-O. Gullström, Markus Büscher, Antoni Szczurek, W. Bardan, S. Schadmand, D. Pszczel, Rudolf Maier, Ankhi Roy, P. Kulessa, P. Adlarson, J. Stepaniak, W. Erven, Wiktor Parol, Zbigniew Rudy, I. Schätti-Ozerianska, K. Lalwani, Magdalena Skurzok, Eryk Czerwiński, B. Mariański, Aleksandra Wrońska, K. Pysz, P. Fedorets, Harald Kleines, E. Perez del Rio, Hans Calén, B. Kamys, P. Wüstner, F. S. Bergmann, Wojciech Krzemien, Magnus Wolke, M. Berłowski, H. P. Morsch, H. Ohm, Kjell Fransson, H. Clement, Frank Goldenbaum, T. Skorodko, T. Sefzick, Pawel Marciniewski, P. Żuprański, M. Żurek, J. Ritman, V. Serdyuk, Jerzy Smyrski, Ralf Engels, Günter Kemmerling, W. Eyrich, N. Hüsken, Christoph Hanhart, Stanisław Kistryn, Lena Heijkenskjöld, D. Prasuhn, A. Pyszniak, W. Augustyniak, Paweł Moskal, V. Hejny, Akira Yamamoto, A. Kupść, Di. Kirillov, and A.E. Bondar
Subjects: Physics, Quark, Nuclear and High Energy Physics, Meson, 010308 nuclear & particles physics, Spontaneous symmetry breaking, Hadron, Charge (physics), 01 natural sciences, Nuclear physics, Pion, 0103 physical sciences, Isobar, Symmetry breaking, Atomic physics, 010306 general physics
Abstract: This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd→4Heπ0 using the WASA-at-COSY detector setup at an excess energy of Q=60MeV. The determined differential cross section can be parametrized as dσ/dΩ=a+bcos2⁡θ⁎, where θ⁎ is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a=(1.55±0.46(stat)+0.32−0.8(syst))pb/sr and b=(13.1±2.1(stat)−2.7+1.0(syst))pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the Δ isobar to the dd→4Heπ0 reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions.
Published: 2018

22. Isotensor Dibaryon in the pp→ppπ^{+}π^{-} Reaction?

Author: P, Adlarson, W, Augustyniak, W, Bardan, M, Bashkanov, F S, Bergmann, M, Berłowski, A, Bondar, M, Büscher, H, Calén, I, Ciepał, H, Clement, E, Czerwiński, K, Demmich, R, Engels, A, Erven, W, Erven, W, Eyrich, P, Fedorets, K, Föhl, K, Fransson, F, Goldenbaum, A, Goswami, K, Grigoryev, L, Heijkenskjöld, V, Hejny, N, Hüsken, L, Jarczyk, T, Johansson, B, Kamys, G, Kemmerling, A, Khoukaz, O, Khreptak, D A, Kirillov, S, Kistryn, H, Kleines, B, Kłos, W, Krzemień, P, Kulessa, A, Kupść, K, Lalwani, D, Lersch, B, Lorentz, A, Magiera, R, Maier, P, Marciniewski, B, Mariański, H-P, Morsch, P, Moskal, H, Ohm, W, Parol, E, Perez Del Rio, N M, Piskunov, D, Prasuhn, D, Pszczel, K, Pysz, J, Ritman, A, Roy, Z, Rudy, O, Rundel, S, Sawant, S, Schadmand, I, Schätti-Ozerianska, T, Sefzick, V, Serdyuk, B, Shwartz, T, Skorodko, M, Skurzok, J, Smyrski, V, Sopov, R, Stassen, J, Stepaniak, E, Stephan, G, Sterzenbach, H, Stockhorst, H, Ströher, A, Szczurek, A, Trzciński, M, Wolke, A, Wrońska, P, Wüstner, A, Yamamoto, J, Zabierowski, M J, Zieliński, J, Złomańczuk, P, Żuprański, and M, Żurek
Abstract: Exclusive measurements of the quasifree pp→ppπ^{+}π^{-} reaction have been carried out at WASA@COSY by means of pd collisions at T_{p}=1.2 GeV. Total and differential cross sections have been extracted covering the energy region T_{p}=1.08-1.36 GeV, which is the region of N^{*}(1440) and Δ(1232)Δ(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor ΔN dibaryon resonance with I(J^{P})=2(1^{+}) produced associatedly with a pion is able to overcome these deficiencies.
Published: 2018

23. Total and differential cross sections of η -production in proton–deuteron fusion for excess energies between Q η = 13 MeV and Q η = 81 MeV

Author: B.A. Shwartz, A. Khoukaz, M. Bashkanov, A. Erven, K. Sitterberg, Hans Calén, K. Grigoryev, Stanisław Kistryn, D. Pszczel, P. Adlarson, Kjell Fransson, K. Pysz, P. Fedorets, D. Lersch, A. Khreptak, S. Schadmand, H. Clement, Ankhi Roy, A. Pyszniak, W. Augustyniak, Günter Kemmerling, H. Ströher, K. Lalwani, I. Schätti-Ozerianska, L. Jarczyk, Zbigniew Rudy, Lena Heijkenskjöld, D. Prasuhn, P. Kulessa, C.-O. Gullström, Frank Goldenbaum, T. Johansson, F. S. Bergmann, Eryk Czerwiński, W. Eyrich, B. Kłos, W. Erven, Magnus Wolke, Wiktor Parol, Markus Büscher, J. Stepaniak, Pawel Marciniewski, N. Hüsken, Harald Kleines, C. Wilkin, Izabela Ciepał, S. Sawant, A. Kuzmin, Jozef Zlomanczuk, J. Zabierowski, H. P. Morsch, G. Sterzenbach, B. Lorentz, P. Żuprański, A. Trzcinski, Hans Stockhorst, Di. Kirillov, Antoni Szczurek, G. Khatri, A. Magiera, V. Serdyuk, Paweł Moskal, James Ritman, Ralf Engels, Rolf Stassen, A. Goswami, Jerzy Smyrski, B. Kamys, K. Demmich, Wojciech Krzemien, P. Wüstner, Oleksandr Rundel, N.M. Piskunov, A.E. Bondar, R. Maier, V. Hejny, Akira Yamamoto, A. Kupść, Aleksandra Wrońska, E. Perez del Rio, E. Stephan, K. Föhl, Magdalena Skurzok, H. Ohm, V. Sopov, W. Bardan, B. Mariański, M. Berłowski, T. Skorodko, Marcin Zieliński, T. Sefzick, and M. Żurek
Subjects: Nuclear and High Energy Physics, eta meson, Proton, Meson, Hadron, Nuclear Theory, Elementary particle, η meson, 7. Clean energy, 01 natural sciences, Nuclear physics, Subatomär fysik, proton–deuteron interactions, Astronomi, astrofysik och kosmologi, 0103 physical sciences, протон-дейтронные взаимодействия, Subatomic Physics, Astronomy, Astrophysics and Cosmology, ddc:530, 010306 general physics, Nuclear Experiment, Boson, Physics, 010308 nuclear & particles physics, Eta meson, Meson production, lcsh:QC1-999, Deuterium, meson production, Proton-deuteron interactions, \eta meson, мезоны, Physics::Accelerator Physics, High Energy Physics::Experiment, ηмезоны, Beam (structure), lcsh:Physics
Abstract: New data on both total and differential cross sections of the production of η mesons in proton–deuteron fusion to He3η in the excess energy region 13.6MeV≤Qη≤80.9MeV are presented. These data have been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum Jülich, using a proton beam at 15 different beam momenta between pp=1.60GeV/c and pp=1.74GeV/c. While significant structure of the total cross section is observed in the energy region 20MeV≲Qη≲60MeV, a previously reported sharp variation around Qη≈50MeV cannot be confirmed. Angular distributions show the typical forward-peaking that was noted earlier. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a wide interval.
Published: 2018

24. Charge symmetry breaking in dd→He4π0 with WASA-at-COSY

Author: Izabela Ciepał, H. Bhatt, Hans Stockhorst, V. Sopov, D. Lersch, Marcin Zieliński, Rolf Stassen, A. Pricking, Bo Höistad, Jozef Zlomanczuk, A.S. Kuzmin, C.-O. Gullström, Markus Büscher, C. F. Redmer, A. Goswami, E. Doroshkevich, B. Mariański, Aleksandra Wrońska, E. Perez del Rio, P. Goslawski, K. Demmich, P. Wurm, H. Clement, K. Lalwani, Stanisław Kistryn, W. Eyrich, D. Coderre, R. Varma, M. Berłowski, A. Pyszniak, W. Augustyniak, K. Föhl, I. Ozerianska, W. Bardan, L. Yurev, P. Podkopał, S. Sawant, Lena Heijkenskjöld, F. S. Bergmann, A. Zink, Zbigniew Rudy, F. Hauenstein, D. Prasuhn, Paweł Moskal, R. Siudak, Magnus Wolke, T. Skorodko, N. Hüsken, Ankhi Roy, R. Maier, J. Stepaniak, W. Erven, P. Kulessa, Eryk Czerwiński, V. Hejny, S. Schadmand, Akira Yamamoto, A. Kupść, B. Kamys, T. Sefzick, Harald Kleines, P. Wüstner, K. Grigoryev, P. Adlarson, Christoph Hanhart, H. Ströher, E. Stephan, N.M. Piskunov, T. Johansson, M. Żurek, L. Jarczyk, B. Kłos, Wojciech Krzemien, K. Pysz, P. Fedorets, Ferdous Khan, Pawel Marciniewski, H. Ohm, V. Serdyuk, B.A. Shwartz, A. Khoukaz, H. P. Morsch, Jerzy Smyrski, M. Mikirtychiants, Magdalena Skurzok, M. Bashkanov, Günter Kemmerling, A. Trzciński, A. Erven, G. Sterzenbach, B. Lorentz, D. Pszczel, Ralf Engels, A. Täschner, A. Magiera, James Ritman, Frank Goldenbaum, P. Żuprański, A.E. Bondar, Hans Calén, Di. Kirillov, J. Zabierowski, Kjell Fransson, and Antoni Szczurek
Subjects: Physics, Quark, Nuclear and High Energy Physics, Particle physics, Chiral perturbation theory, 010308 nuclear & particles physics, Nuclear Theory, Observable, Charge (physics), 01 natural sciences, Nuclear physics, 0103 physical sciences, Sum rule in quantum mechanics, Symmetry breaking, Nuclear Experiment, 010306 general physics
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 cu ...
Published: 2014

25. Spin dependence of {\eta} meson production in proton-proton collisions close to threshold

Author: M. Bashkanov, Günter Kemmerling, A. Erven, I. Schätti-Ozerianska, K. Sitterberg, G. Sterzenbach, W. Eyrich, A. Magiera, B. Lorentz, H. P. Morsch, O. Khreptak, Ralf Engels, N. Hüsken, Paweł Moskal, Zbigniew Rudy, Marcin Zieliński, Eryk Czerwiński, C.-O. Gullström, Markus Büscher, Harald Kleines, Ankhi Roy, W. Bardan, Aleksandra Wrońska, Hans Calén, E. Perez del Rio, T. Sefzick, Stanisław Kistryn, J. Zabierowski, K. Pysz, V. Hejny, Akira Yamamoto, Kjell Fransson, Lena Heijkenskjöld, D. Prasuhn, Antoni Szczurek, A. Khoukaz, Magdalena Skurzok, B. Mariański, K. Grigoryev, Jozef Zlomanczuk, Wojciech Krzemien, V. Sopov, Andrzej Kupsc, Patrik Adlarson, Frank Goldenbaum, Pawel Marciniewski, Damian Pszczel, B. Shwartz, J. Stepaniak, P. Zupranski, D. Lersch, J. Ritman, A. Trzcinski, G. Khatri, P. Fedorets, W. Augustyniak, Tord Johansson, L. Jarczyk, W. Erven, V. Serdyuk, Steven D. Bass, H. Ohm, H. Clement, M. Berłowski, K. Föhl, K. Lalwani, A. Bondar, H. Stroeher, Maria Zurek, Jerzy Smyrski, B. Kamys, P. Wüstner, B. Kłos, T. Skorodko, S. Schadmand, K. Demmich, A. Pyszniak, S. Sawant, Di. Kirillov, A. Kuzmin, F. S. Bergmann, Magnus Wolke, Izabela Ciepał, A. Goswami, Hans Stockhorst, Rolf Stassen, Rudolf Maier, P. Kulessa, Wiktor Parol, Oleksandr Rundel, E. Stephan, and N.M. Piskunov
Subjects: Nuclear Theory, General Physics and Astronomy, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, 0103 physical sciences, ddc:530, FACILITY, NEAR-THRESHOLD, 010306 general physics, NUCLEON, Nuclear Experiment, Nuclear theory, Physics, QUASI-FREE, 010308 nuclear & particles physics, Eta meson, Detector, COSY, Polarization (waves), Near threshold, High Energy Physics - Phenomenology, Physics::Accelerator Physics, Axial symmetry, Nucleon
Abstract: Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high degree of the polarized proton beam of COSY, the reaction pp{\to} pp{\eta} has been measured close to threshold to explore the analyzing power Ay. The angular distribution of Ay is determined with the precision improved by more than one order of magnitude with respect to previous results allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q = 15 MeV signaling s wave production with no evidence for higher partial waves. At Q = 72 MeV the data reveals strong interference of P s and P p partial waves and cancellation of (P p) and Ss*Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the {\eta} meson., Comment: Accepted for publication in Phys. Rev. Lett
Published: 2017

26. Measurements of branching ratios for η decays into charged particles

Author: A. Kupść, Oleksandr Rundel, Akira Yamamoto, T. Johansson, B. Kłos, K. Fransson, E. Stephan, K. Grigoryev, B. Kamys, R. Engels, P. Wüstner, K. Pysz, Ferdous Khan, S. Sawant, Zbigniew Rudy, L. Jarczyk, V. Hejny, K. Föhl, Jozef Zlomanczuk, C.-O. Gullström, Markus Büscher, P. Fedorets, Ankhi Roy, Paweł Moskal, D. Lersch, A. Trzcinski, T. Sefzick, Marcin Zieliński, Stanisław Kistryn, A.E. Bondar, B. Shwartz, J. Stepaniak, A. Magiera, Eryk Czerwiński, R. Varma, K. Demmich, Lena Heijkenskjöld, D. Prasuhn, I. Ozerianska, Harald Kleines, G. Khatri, P. Kulessa, J. Zabierowski, Pawel Marciniewski, M. Berłowski, H. P. Morsch, W. Eyrich, Himani Bhatt, Antoni Szczurek, T. Skorodko, F. S. Bergmann, Magnus Wolke, Aleksandra Wrońska, E. Perez del Rio, A. Kuzmin, J. Ritman, P. Adlarson, N. Hüsken, V. Serdyuk, A. Pyszniak, W. Augustyniak, Jerzy Smyrski, K. Lalwani, M. Żurek, H. Ohm, H. Clement, P. Wurm, N.M. Piskunov, S. Schadmand, B. Mariański, Wojciech Krzemien, W. Erven, R. Siudak, D. Coderre, W. Bardan, M. Mikirtychiants, Magdalena Skurzok, Ulrich Wiedner, V. Sopov, D. Pszczel, R. Maier, H. Ströher, Di. Kirillov, G. Sterzenbach, B. Lorentz, A. Täschner, Günter Kemmerling, Frank Goldenbaum, P. Żuprański, Hans Calén, M. Bashkanov, A. Erven, K. Sitterberg, A. Khoukaz, Izabela Ciepał, A. Goswami, Hans Stockhorst, Rolf Stassen, and A. Zink
Subjects: Energy loss, Particle physics, Meson, Dalitz plot, Branching (polymer chemistry), 01 natural sciences, Subatomär fysik, Conversion Decays, Subatomic Physics, 0103 physical sciences, ddc:530, Gamma, Transition Form-Factors, Nuclear Experiment, 010306 general physics, Na60, Physics, Omega, 010308 nuclear & particles physics, Branching fraction, High Energy Physics::Phenomenology, Detector, Mu(+)Mu(-)Gamma, Charged particle, Crystallography, High Energy Physics::Experiment
Abstract: The WASA-at-COSY experiment has collected $3\ifmmode\times\else\texttimes\fi{}{10}^{7}$ events with $\ensuremath{\eta}$ mesons produced via the reaction $pd\ensuremath{\rightarrow}^{3}\mathrm{He}\phantom{\rule{0.16em}{0ex}}\ensuremath{\eta}$ at $\mathrm{T}=1.0\phantom{\rule{4pt}{0ex}}\mathrm{GeV}$. Using this data set, we evaluate the branching ratios of the decays $\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$, $\ensuremath{\eta}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\gamma}$, $\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{e}^{+}{e}^{\ensuremath{-}}$, and $\ensuremath{\eta}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{e}^{+}{e}^{\ensuremath{-}}$. The branching ratios are normalized to the $\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ decay. In addition an upper limit on a $CP$-violating asymmetry in $\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{e}^{+}{e}^{\ensuremath{-}}$ is extracted.
Published: 2016

27. Search for a dark photon in the π0→e+e−γ decay

Author: M. Mikirtychiants, Magdalena Skurzok, C. F. Redmer, Bo Höistad, G. J. Wagner, Jozef Zlomanczuk, A. Magiera, P. Goslawski, T. Sefzick, W. Eyrich, James Ritman, B. Mariański, C.-O. Gullström, Markus Büscher, H. Clement, Zbigniew Rudy, R. Siudak, Eryk Czerwiński, A. Trzcinski, Harald Kleines, Aleksandra Wrońska, Ulf-G. Meißner, A. Bondar, E. Perez del Rio, N. Shah, K. Pysz, P. Fedorets, Ferdous Khan, W. Zipper, P. Adlarson, W. Bardan, J. Zabierowski, K. Lalwani, Ankhi Roy, M. Hodana, Antoni Szczurek, P. Wurm, H. P. Morsch, H. Ohm, R. Varma, D. Pszczel, M. Żurek, Izabela Ciepał, T. Johansson, I. Ozerianska, V. Hejny, K. Föhl, B. Kłos, M. Siemaszko, Hans Stockhorst, V. Sopov, E. Stephan, H. Ströher, Marcin Zieliński, Frank Goldenbaum, S. Sawant, Pawel Marciniewski, F. Hauenstein, P. Podkopał, Rolf Stassen, K. Grigoryev, E. Doroshkevich, B. Shwartz, J. Stepaniak, Stanisław Kistryn, P. Pluciński, Alexander Schmidt, M. Krapp, P. Żuprański, F. Hinterberger, Hans Calén, R. Maier, Lena Heijkenskjöld, A. Jany, D. Prasuhn, Wojciech Krzemien, L. Li, Kjell Fransson, W. Wȩglorz, T. Tolba, Akira Yamamoto, A. Kupść, M. Berłowski, W. Erven, L. Jarczyk, Andreas Wirzba, A. Pricking, T. Skorodko, K. Demmich, V. Serdyuk, Di. Kirillov, G. Sterzenbach, B. Lorentz, Jerzy Smyrski, M. Bashkanov, F. S. Bergmann, Ralf Engels, Magnus Wolke, Paweł Moskal, Günter Kemmerling, S. Schadmand, B. Kamys, A. Pyszniak, W. Augustyniak, P. Wüstner, A. Goswami, A. Khoukaz, Himani Bhatt, Basanta Kumar Nandi, N.M. Piskunov, Benedykt R. Jany, P. Kulessa, A. Kuzmin, J. Klaja, D. Coderre, and D. Lersch
Subjects: Physics, Nuclear and High Energy Physics, Muon, Anomalous magnetic dipole moment, Magnetic moment, 010308 nuclear & particles physics, Elementary particle, 01 natural sciences, 7. Clean energy, Dark photon, Nuclear physics, Massless particle, Particle decay, 0103 physical sciences, 010306 general physics, Lepton
Abstract: The presently world largest data sample for π 0 → γ e + e − decays studies containing nearly 5 × 10 5 events was collected using the WASA detector at COSY. A search for a dark photon U produced in the π 0 → γ U → γ e + e − decay from the p p → p p π 0 reaction was carried out. An upper limit on the square of the U − γ mixing strength parameter ϵ 2 of 5 × 10 − 6 at 90% CL was obtained for the mass range 20 MeV M U 100 MeV . This result together with other recent experimental limits significantly reduces the M U vs. ϵ 2 parameter space which could explain the presently seen deviation between the Standard Model prediction and the direct measurement of the anomalous magnetic moment of the muon.
Published: 2013

28. Exclusive measurement of the η→π+π−γ decay

Author: Paweł Moskal, B. Lorentz, A. Magiera, Ulf-G. Meißner, M. Berłowski, H. P. Morsch, C. Adolph, C.-O. Gullström, Markus Büscher, B. Kamys, Benedykt R. Jany, A. Winnemöller, Jozef Zlomanczuk, James Ritman, Joanna Klaja, M. Mikirtychiants, D. Coderre, P. Wüstner, P. Goslawski, Magdalena Skurzok, R. Maier, G. J. Wagner, S. Schadmand, H. Clement, P. Fedorets, G. Sterzenbach, Günter Kemmerling, Bo Höistad, Paweł Podkopał, W. Eyrich, F. Stollenwerk, J. Heimlich, L. Jarczyk, A. Trzciński, T. Skorodko, A. Schmidt, Aleksandra Wrońska, A. Povtoreyko, E. Perez del Rio, X. Yuan, Tomasz Bednarski, Annika Passfeld, Zbigniew Rudy, H. Bhatt, W. Erven, Basanta Kumar Nandi, T. Sefzick, Stanisław Kistryn, J. Stepaniak, R. Engels, A. Pricking, D. Prasuhn, K. Föhl, R. Varma, P. Wurm, Andreas Wirzba, P. Pluciński, Eryk Czerwiński, K. T Brinkmann, K. Grigoryev, C. Zheng, Szymon Niedźwiecki, Harald Kleines, P. Vlasov, M. Hodana, W. Zipper, Lena Heijkenskjöld, W. Bardan, C. F. Redmer, P. Adlarson, P. Kulessa, T. Tolba, V. Serdyuk, R. Siudak, Hans Stockhorst, L. Yurev, Pawel Marciniewski, A. Täschner, H. Ohm, K. Pysz, T. Rausmann, Rolf Stassen, Christoph Hanhart, E. Doroshkevich, J. Zabierowski, F. Hinterberger, A. Jany, M. Siemaszko, Antoni Szczurek, Wojciech Krzemien, V. Sopov, F. S. Bergmann, Magnus Wolke, F. Kren, Jerzy Smyrski, Hans Calén, Kjell Fransson, T. Johansson, Frank Goldenbaum, B. Kłos, W. Węglorz, A. Pyszniak, W. Augustyniak, V. Hejny, S. Sawant, A. Kupść, Carla Terschlüsen, M. Bashkanov, P. Żuprański, Stefan Leupold, K. Lalwani, Y. Petukhov, A. Khoukaz, N.M. Piskunov, Marek Jacewicz, C. Pauly, N. Shah, Marcin Zieliński, H. Ströher, Ankhi Roy, O. Khakimova, B. Mariański, and T. Petri
Subjects: Physics, Nuclear and High Energy Physics, Proton, Meson, 010308 nuclear & particles physics, Nuclear Theory, Eta meson, Hadron, 01 natural sciences, 7. Clean energy, Nuclear physics, Pion, Helium-3, 0103 physical sciences, Physics::Accelerator Physics, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Isotopes of helium, Dimensionless quantity
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 -> He-3 X at a proton be ...
Published: 2012

29. ABC effect and resonance structure in the double-pionic fusion toHe3

Author: V. Hejny, Akira Yamamoto, A. Kupść, Frank Goldenbaum, A. Khoukaz, Pawel Marciniewski, K. Lalwani, Jozef Zlomanczuk, A. Kuzmin, J. Ritman, V. Serdyuk, P. Żuprański, Jerzy Smyrski, Bo Höistad, M. Berłowski, B. Kamys, P. Wüstner, G. J. Wagner, P. Adlarson, A. Magiera, Hans Calén, F. S. Bergmann, S. Schadmand, R. Varma, S. Sawant, Magnus Wolke, W. Eyrich, A. Zink, K. Pysz, P. Fedorets, M. Bashkanov, P. Goslawski, Kjell Fransson, I. Ozerianska, Ferdous Khan, N. Hüsken, H. Ohm, G. Sterzenbach, D. Pszczel, T. Skorodko, B. Lorentz, P. Podkopał, H. Clement, A. Pyszniak, W. Augustyniak, Alexander Bondar, T. Sefzick, R. Maier, Di. Kirillov, Zbigniew Rudy, M. Żurek, A. Erven, E. Stephan, Ralf Engels, F. Hauenstein, Paweł Moskal, Eryk Czerwiński, T. Johansson, B. Shwartz, J. Stepaniak, M. Mikirtychiants, Magdalena Skurzok, Aleksandra Wrońska, A. Täschner, B. Mariański, Harald Kleines, B. Kłos, E. Perez del Rio, Izabela Ciepał, A. Goswami, A. Pricking, P. Wurm, D. Lersch, H. Ströher, H. P. Morsch, Wojciech Krzemien, W. Erven, Hans Stockhorst, Stanisław Kistryn, E. Doroshkevich, K. Demmich, C.-O. Gullström, Markus Büscher, Marcin Zieliński, N.M. Piskunov, Rolf Stassen, H. Bhatt, Lena Heijkenskjöld, D. Prasuhn, J. Zabierowski, K. Grigoryev, Antoni Szczurek, L. Jarczyk, Günter Kemmerling, K. Föhl, A. Trzciński, P. Kulessa, L. Yurev, V. Sopov, Ankhi Roy, R. Siudak, W. Bardan, and D. Coderre
Subjects: Mass enhancement, Nuclear physics, Physics, Nuclear and High Energy Physics, Fusion, Near threshold, Angular distribution, Meson production, Dalitz plot, Pi interaction, 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 enhan ...
Published: 2015

30. Measurement of theη→π+π−π0Dalitz plot distribution

Author: M. Hodana, C. F. Redmer, Himani Bhatt, E. Stephan, D. Pszczel, G. Sterzenbach, B. Lorentz, B. Mariański, A. Magiera, A.E. Bondar, S. Sawant, A. Zink, F. S. Bergmann, Magnus Wolke, S. Schadmand, P. Goslawski, Akira Yamamoto, B. Shwartz, J. Stepaniak, K. Grigoryev, N.M. Piskunov, Ankhi Roy, Pawel Marciniewski, Di. Kirillov, P. Adlarson, K. Fransson, A. Täschner, H. Clement, P. Podkopał, L. Jarczyk, A. Kuzmin, A. Kupść, J. Ritman, V. Serdyuk, R. Maier, T. Johansson, H. Ohm, L. Yurev, Jerzy Smyrski, B. Kamys, B. Kłos, Ulf-G. Meißner, K. Demmich, R. Engels, H. P. Morsch, Stanisław Kistryn, A. Trzcinski, P. Wüstner, Paweł Moskal, M. Żurek, Aleksandra Wrońska, E. Perez del Rio, X. Yuan, V. Sopov, Benedykt R. Jany, F. Hauenstein, Lena Heijkenskjöld, A. Pricking, Wojciech Krzemien, D. Prasuhn, P. Wurm, Marcin Zieliński, P. Kulessa, M. Mikirtychiants, Magdalena Skurzok, W. Erven, M. Bashkanov, Jozef Zlomanczuk, Izabela Ciepał, Zbigniew Rudy, A. Goswami, K. Lalwani, K. Pysz, Günter Kemmerling, A. Erven, R. Siudak, W. Bardan, Ferdous Khan, Hans Stockhorst, A. Pyszniak, W. Augustyniak, C. Zheng, B. V. Martemyanov, Rolf Stassen, D. Lersch, Eryk Czerwiński, J. Zabierowski, A. Khoukaz, Harald Kleines, Antoni Szczurek, D. Coderre, Bo Höistad, H. Ströher, W. Eyrich, N. Hüsken, V. Hejny, K. Föhl, C.-O. Gullström, Markus Büscher, P. Fedorets, M. Berłowski, T. Skorodko, Hans Calén, Frank Goldenbaum, E. Doroshkevich, A. Jany, P. Żuprański, T. Sefzick, R. Varma, and I. Ozerianska
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Distribution (number theory), Meson, 010308 nuclear & particles physics, 0103 physical sciences, Dalitz plot, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, 01 natural sciences
Abstract: The Dalitz plot distribution of the $\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ decay is determined by using a data sample of $1.2\ifmmode\times\else\texttimes\fi{}{10}^{7}$ $\ensuremath{\eta}$ mesons from the $pd\ensuremath{\rightarrow}^{3}\mathrm{He}\ensuremath{\eta}$ reaction at 1 GeV collected by the WASA detector at COSY.
Published: 2014

31. Cross section ratio and angular distributions of the reaction p + d -> 3He + eta at 48.8 MeV and 59.8 MeV excess energy

Author: M. Bashkanov, Benedykt R. Jany, A. Erven, E. Stephan, R. Siudak, W. Bardan, K. Lalwani, D. Lersch, P. Podkopał, H. P. Morsch, C. F. Redmer, A. Zink, R. Maier, G. J. Wagner, A. Magiera, B. Mariański, Jozef Zlomanczuk, S. Sawant, V. Sopov, D. Coderre, Günter Kemmerling, Aleksandra Wrońska, W. Eyrich, E. Perez del Rio, V. Hejny, K. Föhl, Stanisław Kistryn, K. Demmich, P. Goslawski, F. Hauenstein, Lena Heijkenskjöld, D. Prasuhn, A. Trzciński, A. Kupść, L. Yurev, N. Hüsken, P. Wurm, T. Johansson, Himani Bhatt, Annika Passfeld, A. Khoukaz, P. Kulessa, H. Clement, M. Hodana, B. Kłos, A. Pricking, W. Węglorz, E. Doroshkevich, M. Żurek, A. Pyszniak, W. Augustyniak, A. Jany, Ankhi Roy, C.-O. Gullström, Markus Büscher, H. Ohm, N.M. Piskunov, R. Varma, M. Berłowski, Paweł Moskal, W. Erven, P. Fedorets, H. Ströher, Marcin Zieliński, M. Krapp, F. S. Bergmann, I. Ozerianska, J. Stepaniak, Akira Yamamoto, T. Skorodko, Magnus Wolke, K. Fransson, T. Sefzick, Hans Calén, B. Kamys, P. Wüstner, K. Grigoryev, Frank Goldenbaum, K. Pysz, Pawel Marciniewski, Ferdous Khan, J. Ritman, V. Serdyuk, P. Żuprański, Jerzy Smyrski, S. Schadmand, P. Adlarson, M. Mikirtychiants, Magdalena Skurzok, Bo Höistad, Izabela Ciepał, A. Goswami, Zbigniew Rudy, L. Jarczyk, Eryk Czerwiński, G. Sterzenbach, B. Lorentz, Harald Kleines, Hans Stockhorst, Ralf Engels, A. Täschner, Rolf Stassen, Di. Kirillov, D. Pszczel, J. Zabierowski, Antoni Szczurek, and Wojciech Krzemien
Subjects: Physics, Nuclear and High Energy Physics, Proton, 010308 nuclear & particles physics, Nuclear Theory, Intermediate Energies, Eta, 01 natural sciences, 7. Clean energy, Nuclear physics, Cross section (physics), Tensor Analyzing Power, Deuterium, Near-Threshold, 0103 physical sciences, Energy interval, Physics::Accelerator Physics, ddc:530, 010306 general physics, Nuclear Experiment, Excess energy, Beam (structure)
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

32. Evidence for a New Resonance from Polarized Neutron-Proton Scattering

Author: A. Magiera, M. Buescher, James Ritman, M. Mikirtychiants, Magdalena Skurzok, F. Hauenstein, T. Sefzick, A. Taeschner, H. Stockhorst, L. Yurev, K. Lalwani, J. Stepaniak, Jozef Zlomanczuk, Frank Goldenbaum, G. J. Wagner, A. Khoukaz, Paweł Moskal, Tord Johansson, Wojciech Krzemien, M. Krapp, P. Goslawski, R. Stassen, B. Kamys, P. Zupranski, F. S. Bergmann, A. Zink, M. Hodana, W. Eyrich, K. Foehl, A. Pricking, D. Lersch, K. Pysz, P. Fedorets, Ferdous Khan, H. Stroeher, I. I. Strakovsky, Aleksandra Wrońska, E. Perez del Rio, H. Ohm, N. Huesken, Günter Kemmerling, Izabela Ciepał, A. Goswami, M. Bashkanov, P. Wurm, Di. Kirillov, R. Varma, H. P. Morsch, C. F. Redmer, K. Grigoryev, A. Erven, E. Doroshkevich, M. Wolke, Hans Calén, I. Ozerianska, J. Zabierowski, A. Pyszniak, W. Augustyniak, Bo Höistad, A. Jany, Antoni Szczurek, W. J. Briscoe, D. Pszczel, Kjell Fransson, P. Podkopał, Andrzej Kupsc, Akira Yamamoto, A. Trzciński, Said Data Anal Ctr, M. Berłowski, S. Schadmand, R. Maier, L. Jarczyk, Stanisław Kistryn, B. Lorentz, P. Wuestner, V. Hejny, Anubhab Roy, Lena Heijkenskjöld, T. Skorodko, E. Stephan, V. Sopov, P. Adlarson, K. Demmich, Zbigniew Rudy, Pawel Marciniewski, R. Siudak, Eryk Czerwiński, Harald Kleines, V. Serdyuk, Jerzy Smyrski, B. Kłos, G. Sterzenbach, Ralf Engels, Ron L. Workman, S. Sawant, W. Erven, Marcin Zieliński, B. Mariański, P. Kulessa, H. Clement, C.-O. Gullström, N.M. Piskunov, H. Bhatt, Benedykt R. Jany, Maria Zurek, W. Bardan, D. Prasuhn, and D. Coderre
Subjects: Physics, Elastic scattering, States, Scattering, Partial wave analysis, Dibaryon, Nuclear Theory, FOS: Physical sciences, General Physics and Astronomy, Hexaquark, Analyzing Power, Resonance (particle physics), Nuclear physics, Angular distribution, Elastic-Scattering, Proton scattering, ddc:550, Neutron, Nuclear Experiment (nucl-ex), Nuclear Experiment, Partial-Wave Analysis, Spin Observables
Abstract: Exclusive and kinematically complete high-statistics measurements of quasifree polarized (n) over right arrowp scattering have been performed in the energy region of the narrow resonancelike structure d* with I(J(P)) = 0(3(+)),M approximate to 2380 MeV, and Gamma approximate to 70 MeV observed recently in the double-pionic fusion channels pn -> d pi(0)pi(0) and pn -> 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 (d) over right arrowp -> np + p(spectator). This allowed the np analyzing power, A(y), to be measured over a broad 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 D-3(3) - (3)G(3) waves in support of the d* resonance hypothesis.
Published: 2014

33. Measurement of thepn→ppπ0π−reaction in search for the recently observed resonance structure indπ0π0anddπ+π−systems

Author: Di. Kirillov, H. Ströher, D. Lersch, N. Shah, G. J. Wagner, S. Schadmand, Alexander Schmidt, W. Eyrich, R. Varma, K. Grigoryev, K. Demmich, I. Ozerianska, E. Doroshkevich, W. Erven, L. Li, A. Jany, Pawel Marciniewski, Jozef Zlomanczuk, Stanisław Kistryn, Lena Heijkenskjöld, D. Prasuhn, T. Tolba, C.-O. Gullström, X. Yuan, Markus Büscher, V. Hejny, Akira Yamamoto, A. Kupść, T. Johansson, Bo Höistad, H. Bhatt, T. Sefzick, B. Kłos, A. Khoukaz, Günter Kemmerling, C. Zheng, A. Trzciński, W. Węglorz, A. Pyszniak, W. Augustyniak, M. Bashkanov, F. S. Bergmann, J. Ritman, Magnus Wolke, C. F. Redmer, Zbigniew Rudy, Izabela Ciepał, A. Goswami, V. Serdyuk, Hans Stockhorst, Frank Goldenbaum, Paweł Moskal, Rolf Stassen, G. Sterzenbach, B. Lorentz, F. Hinterberger, Jerzy Smyrski, M. Krapp, Eryk Czerwiński, M. Berłowski, Pawel Plucinski, Harald Kleines, B. Kamys, S. Sawant, R. Siudak, W. Zipper, P. Wüstner, W. Bardan, A. Magiera, P. Żuprański, L. Jarczyk, K. Pysz, P. Fedorets, Hans Calén, M. Siemaszko, T. Skorodko, Kjell Fransson, Ferdous Khan, H. P. Morsch, F. Hauenstein, J. Stepaniak, E. Stephan, K. Föhl, M. Hodana, Ankhi Roy, B. Mariański, V. Sopov, P. Goslawski, H. Clement, D. Coderre, P. Kulessa, M. Żurek, Marcin Zieliński, Basanta Kumar Nandi, J. Zabierowski, N.M. Piskunov, R. Engels, P. Podkopał, A. Pricking, Benedykt R. Jany, Antoni Szczurek, J. Klaja, D. Pszczel, R. Maier, Wojciech Krzemien, Aleksandra Wrońska, E. Perez del Rio, P. Wurm, H. Ohm, M. Mikirtychiants, Magdalena Skurzok, P. Adlarson, and K. Lalwani
Subjects: Nuclear physics, Mass enhancement, Physics, Nuclear and High Energy Physics, Roper resonance, Meson production, Pi, Analytical chemistry
Abstract: Exclusive measurements of the quasifree pn -> 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 ...
Published: 2013

34. Investigation of thedd→3Henπ0reaction with the FZ Jülich WASA-at-COSY facility

Author: P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F. S. Bergmann, M. Berłowski, H. Bhatt, M. Büscher, H. Calén, I. Ciepał, H. Clement, D. Coderre, E. Czerwiński, K. Demmich, E. Doroshkevich, R. Engels, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, P. Goslawski, A. Goswami, K. Grigoryev, C.-O. Gullström, C. Hanhart, F. Hauenstein, L. Heijkenskjöld, V. Hejny, F. Hinterberger, M. Hodana, B. Höistad, A. Jany, B. R. Jany, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, F. A. Khan, A. Khoukaz, D. A. Kirillov, S. Kistryn, J. Klaja, H. Kleines, B. Kłos, M. Krapp, W. Krzemień, P. Kulessa, A. Kupść, K. Lalwani, D. Lersch, L. Li, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, M. Mikirtychiants, H.-P. Morsch, P. Moskal, B. K. Nandi, H. Ohm, I. Ozerianska, E. Perez del Rio, N. M. Piskunov, P. Pluciński, P. Podkopał, D. Prasuhn, A. Pricking, D. Pszczel, K. Pysz, A. Pyszniak, C. F. Redmer, J. Ritman, A. Roy, Z. Rudy, S. Sawant, A. Schmidt, S. Schadmand, T. Sefzick, V. Serdyuk, N. Shah, M. Siemaszko, R. Siudak, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, T. Tolba, A. Trzciński, R. Varma, G. J. Wagner, W. Węglorz, M. Wolke, A. Wrońska, P. Wüstner, P. Wurm, A. Yamamoto, X. Yuan, J. Zabierowski, C. Zheng, M. J. Zieliński, W. Zipper, J. Złomańczuk, P. Żuprański, and M. Żurek
Subjects: Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Sigma, State (functional analysis), 01 natural sciences, Nuclear physics, Momentum, Cross section (physics), Norm (mathematics), Phase space, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, Beam (structure)
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.
Published: 2013

35. Search forη-mesic4He with the WASA-at-COSY detector

Author: B. Kamys, Stanisław Kistryn, A. Goswami, Paweł Moskal, W. Zipper, D. Coderre, P. Wüstner, T. Tolba, W. Bardan, M. Bashkanov, Zbigniew Rudy, A. Kupść, Lena Heijkenskjöld, Hans Stockhorst, Rolf Stassen, A. Magiera, V. Serdyuk, D. Prasuhn, V. Hejny, T. Johansson, P. Kulessa, Eryk Czerwiński, T. Sefzick, D. Pszczel, Akira Yamamoto, Szymon Niedźwiecki, B. Kłos, K. Föhl, Harald Kleines, P. Vlasov, P. Goslawski, James Ritman, F. Hinterberger, A. Roy, R. Siudak, K. Pysz, H. Ströher, K. Lalwani, Jozef Zlomanczuk, Ferdous Khan, L. Yurev, R. Engels, Pawel Marciniewski, Frank Goldenbaum, H. Clement, K. Demmich, M. Krapp, S. Schadmand, Bo Höistad, Basanta Kumar Nandi, M. Żurek, C.-O. Gullström, Markus Büscher, P. Adlarson, G. J. Wagner, W. Węglorz, A. Pyszniak, W. Augustyniak, F. S. Bergmann, Magnus Wolke, F. Hauenstein, R. Varma, H. Bhatt, H. Ohm, Jerzy Smyrski, N. Shah, M. Hodana, W. Eyrich, B. Mariański, A. Pricking, P. Fedorets, P. Żuprański, J. Stepaniak, I. Ozerianska, M. Siemaszko, Benedykt R. Jany, J. Zabierowski, X. Yuan, D. Lersch, P. Pluciński, Alexander Schmidt, J. Klaja, Hans Calén, Antoni Szczurek, M. Mikirtychiants, Magdalena Skurzok, W. Erven, C. Zheng, Aleksandra Wrońska, E. Perez del Rio, V. Sopov, H. P. Morsch, C. F. Redmer, L. Li, P. Wurm, Wojciech Krzemien, Kjell Fransson, Marcin Zieliński, P. Podkopał, R. Maier, E. Doroshkevich, K. Grigoryev, L. Jarczyk, A. Jany, E. Stephan, M. Berłowski, T. Skorodko, A. Khoukaz, G. Sterzenbach, B. Lorentz, S. Sawant, Günter Kemmerling, A. Trzciński, and Tomasz Bednarski
Subjects: Excitation function, Physics, Nuclear and High Energy Physics, Particle physics, Meson, 010308 nuclear & particles physics, Detector, 01 natural sciences, Synchrotron, law.invention, Nuclear physics, law, 0103 physical sciences, Bound state, 010306 general physics
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 ...
Published: 2013

36. Isospin decomposition of the basic double-pionic fusion in the region of the ABC effect

Author: P. Wüstner, M. Mikirtychiants, Magdalena Skurzok, H. Ströher, K. Grigoryev, Pawel Marciniewski, Tord Johansson, V. Serdyuk, Jerzy Smyrski, A. Magiera, S. Sawant, H. Stockhorst, Frank Goldenbaum, M. Żurek, G. Sterzenbach, L. Jarczyk, C.-O. Gullström, James Ritman, Markus Büscher, M. Krapp, A. Pricking, W. Erven, B. Mariański, P. Adlarson, T. Skorodko, G. J. Wagner, A. Khoukaz, Alexander Schmidt, H. P. Morsch, X. Yuan, D. Lersch, H. Ohm, F. S. Bergmann, W. Eyrich, P. Goslawski, Magnus Wolke, R. Stassen, E. Doroshkevich, Günter Kemmerling, T. Tolba, P. Żuprański, Wojciech Krzemien, C. Zheng, A. Trzciński, A. Jany, Jozef Zlomanczuk, F. Hauenstein, K. Föhl, C. F. Redmer, Tomasz Bednarski, L. Yurev, V. Hejny, J. Stepaniak, P. Pluciński, Marcin Zieliński, K. Demmich, P. Podkopał, Lena Heijkenskjöld, M. Hodana, T. Sefzick, W. Węglorz, A. Pyszniak, W. Augustyniak, Hans Calén, K. Pysz, P. Fedorets, D. Pszczel, R. Maier, Ferdous Khan, B. Kłos, H. Bhatt, B. Lorentz, Kjell Fransson, Aleksandra Wrońska, E. Perez del Rio, L. Li, A. Goswami, F. Hinterberger, P. Wurm, M. Berłowski, P. Kulessa, Paweł Moskal, E. Stephan, S. Schadmand, Akira Yamamoto, A. Kupść, M. Bashkanov, N. Shah, K. Lalwani, R. Varma, I. Ozerianska, Benedykt R. Jany, H. Clement, Basanta Kumar Nandi, Bo Höistad, Zbigniew Rudy, R. Siudak, J. Klaja, Eryk Czerwiński, Szymon Niedźwiecki, Harald Kleines, P. Vlasov, W. Zipper, W. Bardan, D. Coderre, V. Sopov, R. Engels, D. Prasuhn, Ankhi Roy, St. Kistryn, M. Siemaszko, J. Zabierowski, Antoni Szczurek, and B. Kamys
Subjects: Nuclear reaction, Nuclear and High Energy Physics, Particle physics, fusion, +deuteron+2pi%22">p nucleon --> deuteron 2pi, Meson, Gev-C, two-pion [mass spectrum], Nuclear Theory, Hadron, isovector, FOS: Physical sciences, Elementary particle, Juelich COSY PS, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, ABC effect and resonance structure, isoscalar, 0103 physical sciences, Pi, Nuclear fusion, Collisions, ddc:530, Meson Production, Nuclear Experiment (nucl-ex), WASA, Nuclear Experiment, 010306 general physics, Physics, 010308 nuclear & particles physics, Double Pion Production, mass enhancement, Pp, energy dependence [channel cross section], Total Cross-Sections, isospin decomposition, p n, Abc Effect And Resonance Structure, double pion production, Isospin, fusion [p p], pair production [pi], Lsospin Decomposition, experimental results
Abstract: Exclusive and kinematically complete high-statistics measurements of the basic double-pionic fusion reactions $pn\rightarrow d\pi ^{0}\pi ^{0}, pn\rightarrow d\pi ^{+}\pi ^{-}$ and $pp\rightarrow d\pi ^{+}\pi ^{0}$ 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 $d\pi ^{0}\pi ^{0}$ channel exhibits the ABC effect, i.e. a low-mass enhancement in the $\pi \pi$ - invariant mass distribution, as well as the associated resonance structure in the total cross section, the isovector part given by the $d\pi ^{+}\pi ^{-}$ channel shows a smooth behavior consistent with the conventional t -channel $\Delta \Delta$ process. The $d\pi^{+}\pi ^{-}$ 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: 2013

37. Abashian-Booth-Crowe resonance structure in the double pionic fusion to He-4

Author: R. Varma, I. Ozerianska, T. Tolba, A. Magiera, S. Schadmand, B. Mariański, P. Wuestner, K. Lalwani, B. Kamys, D. Pszczel, Hans Stockhorst, D. Lersch, Zbigniew Rudy, Rolf Stassen, Jozef Zlomanczuk, M. Berłowski, Patrik Adlarson, Benedykt R. Jany, B. Kłos, M. Buescher, C. Pauly, F. Hinterberger, T. Skorodko, F. S. Bergmann, Magnus Wolke, Eryk Czerwiński, G. Kemmerling, Frank Goldenbaum, P. Goslawski, Ankhi Roy, Stanisław Kistryn, R. Siudak, H. Ohm, W. Zipper, W. Bardan, Paweł Moskal, A. Trzciński, K. Foehl, H. Kleines, P. Vlasov, S. Sawant, Tomasz Bednarski, P. Podkopał, Lena Heijkenskjöld, J. Klaja, P. Zupranski, A. Pricking, N. Shah, D. Prasuhn, M. Bashkanov, H. Clement, Basanta Kumar Nandi, Alexander Schmidt, Wojciech Krzemien, G. Sterzenbach, B. Lorentz, E. Doroshkevich, X. Yuan, Pawel Plucinski, R. Maier, A. Jany, P. Kulessa, Marcin Zieliński, Bo Höistad, G. J. Wagner, C. Zheng, Y. Petukhov, K. Demmich, R. Engels, C. F. Redmer, A. Khoukaz, L. Yurev, W. Węglorz, K. T Brinkmann, W. Augustyniak, W. Eyrich, K. Grigoryev, J. Zabierowski, W. Erven, V. Sopov, Andrzej Kupsc, Antoni Szczurek, D. Coderre, M. Hodana, V. Hejny, Akira Yamamoto, L. Jarczyk, Carl-Oscar Gullström, M. Mikirtychiants, Magdalena Skurzok, Tord Johansson, Aleksandra Wrońska, E. Perez del Rio, Szymon Niedzwiecki, P. Wurm, Pawel Marciniewski, J. Ritman, V. Serdyuk, Jerzy Smyrski, Andzej Pyszniak, Hans Calén, Kjell Fransson, H. Stroeher, C. Husmann, L. Li, H. P. Morsch, H. Bhatt, K. Pysz, P. Fedorets, Ferdous Khan, F. Hauenstein, and J. Stepaniak
Subjects: Nuclear and High Energy Physics, Particle physics, Meson production, two-pion [mass spectrum], pair production [pi0], Juelich COSY PS, 0.4-0.7 GeV/nucleon, +helium+2pi0%22">deuteron deuteron --> helium 2pi0, 7. Clean energy, 01 natural sciences, Nuclear physics, 0103 physical sciences, Nuclear fusion, ddc:530, Collisions, Meson Production, WASA, Nuclear Experiment, 010306 general physics, Inclusive Reaction, Nuclear-Matter, Physics, Range (particle radiation), Fusion, fusion [deuteron deuteron], 010308 nuclear & particles physics, Dibaryons, energy dependence [channel cross section], Nuclear matter, width [resonance], angular dependence [differential cross section], Abc Enhancement, experimental results
Abstract: Exclusive and kinematically complete high-statistics measurements of the double pionic fusion reaction dd -> He-4 pi(0)pi(0) have been performed in the energy range 0.8-1.4 GeV covering thus the region of the Abashian-Booth-Crowe 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 the cooler synchrotron at Forshungszentrum Julich GmbH. Similar to the observation in the basic pn -> d pi(0)pi(0) reaction, the data reveal a correlation between the ABC effect and a resonancelike energy dependence in the total cross section. The maximum occurs at m = 2.37 GeV + 2m(N), i.e., at the same position as in the basic reaction. The observed resonance width Gamma approximate to 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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38. Isotensor Dibaryon in the pp→ppπ^{+}π^{-} Reaction?

Author: Adlarson P, Augustyniak W, Bardan W, Bashkanov M, Bergmann FS, 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, Heijkenskjöld L, Hejny V, Hüsken N, Jarczyk L, Johansson T, Kamys B, Kemmerling G, Khoukaz A, Khreptak O, Kirillov DA, Kistryn S, Kleines H, Kłos B, Krzemień W, Kulessa P, Kupść A, Lalwani K, Lersch D, Lorentz B, Magiera A, Maier R, Marciniewski P, Mariański B, Morsch HP, Moskal P, Ohm H, Parol W, Perez Del Rio E, Piskunov NM, Prasuhn D, Pszczel D, Pysz K, Ritman J, Roy A, Rudy Z, Rundel O, Sawant S, Schadmand S, Schätti-Ozerianska I, Sefzick T, Serdyuk V, Shwartz B, 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 MJ, Złomańczuk J, Żuprański P, and Żurek M
Abstract: Exclusive measurements of the quasifree pp→ppπ^{+}π^{-} reaction have been carried out at WASA@COSY by means of pd collisions at T_{p}=1.2 GeV. Total and differential cross sections have been extracted covering the energy region T_{p}=1.08-1.36 GeV, which is the region of N^{*}(1440) and Δ(1232)Δ(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor ΔN dibaryon resonance with I(J^{P})=2(1^{+}) produced associatedly with a pion is able to overcome these deficiencies.
Published: 2018
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39. Spin Dependence of η Meson Production in Proton-Proton Collisions Close to Threshold.

Author: Adlarson P, Augustyniak W, Bardan W, Bashkanov M, Bass SD, Bergmann FS, 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 CO, Heijkenskjöld L, Hejny V, Hüsken N, Jarczyk L, Johansson T, Kamys B, Kemmerling G, Khatri G, Khoukaz A, Khreptak O, Kirillov DA, 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 HP, Moskal P, Ohm H, Parol W, Perez Del Rio E, Piskunov NM, 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 MJ, Złomańczuk J, Żuprański P, and Żurek M
Abstract: Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high polarization degree of the proton beam of COSY, the reaction p[over →]p→ppη has been measured close to threshold to explore the analyzing power A_{y}. The angular distribution of A_{y} is determined with the precision improved by more than 1 order of magnitude with respect to previous results, allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q=15 MeV, signaling s-wave production with no evidence for higher partial waves. At Q=72 MeV the data reveal strong interference of Ps and Pp partial waves and cancellation of (Pp)^{2} and Ss^{*}Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the η meson.
Published: 2018
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