Isoscalar Single-Pion Production in the Region of Roper and $d^*(2380)$ Resonances

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

Preprint

FZJ-2017-05279

Isoscalar Single-Pion Production in the Region of Roper and $d^*(2380)$ Resonances

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

2017

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Please use a persistent id in citations: http://hdl.handle.net/2128/15005

Abstract: Exclusive measurements of the quasi-free $pn \to pp\pi^-$ and $pp \to pp\pi^0$ reactions have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $T_p = 0.95 - 1.3$ GeV ($\sqrt s$ = 2.3 - 2.46 GeV), which includes the regions of $\Delta(1232)$, $N^*(1440)$ and $d^*(2380)$ resonance excitations. From these measurements the isoscalar single-pion production has been extracted, for which data existed so far only below $T_p$ = 1 GeV. We observe a substantial increase of this cross section above 1 GeV, which can be related to the Roper resonance $N^*(1440)$, the strength of which shows up isolated from the $\Delta$ resonance in the isoscalar $(N\pi)_{I=0}$ invariant-mass spectrum. No evidence for a decay of the dibaryon resonance $d^*(2380)$ into the isoscalar $(NN\pi)_{I=0}$ channel is found. An upper limit of 180 $\mu$b (90 $\%$ C.L.) corresponding to a branching ratio of 9 $\%$ has been deduced.

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