Study of the quasi-free np -> np pi(+)pi(-) reaction with a deuterium beam at 1.25 GeV/nucleon

0454030 - ÚJF 2016 RIV NL eng J - Journal Article
Agakishiev, G. - Balanda, A. - Belver, D. - Belyaev, A. V. - Blanco, A. - Křížek, Filip - Kugler, Andrej - Sobolev, Yuri, G. - Tlustý, Pavel - Wagner, Vladimír … Total 105 authors
Study of the quasi-free np -> np pi(+)pi(-) reaction with a deuterium beam at 1.25 GeV/nucleon.
Physics Letters. B. Roč. 750, NOV (2015), s. 184-193. ISSN 0370-2693. E-ISSN 1873-2445
R&D Projects: GA MŠMT LC07050; GA MŠMT LA316; GA AV ČR IAA100480803
Institutional support: RVO:61389005
Keywords : HADES * two-pion production * n p collisions * resonance excitations
Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders
Impact factor: 4.787, year: 2015

The tagged quasi-free np -> np pi(+)pi(-) reaction has been studied experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI at a deuteron incident beam energy of 1.25 GeV/nucleon (root S similar to 2.42 GeV/c for the quasi-free collision). For the first time, differential distributions of solid statistics for pi(+)pi(-) production in np collisions have been collected in the region corresponding to the large transverse momenta of the secondary particles. The invariant mass and angular distributions for the np -> np pi(+)pi(-) reaction are compared with different models. This comparison confirms the dominance of the t-channel with Delta Delta contribution. It also validates the changes previously introduced in the Valencia model to describe two-pion production data in other isospin channels, although some deviations are observed, especially for the pi(+)pi(-) invariant mass spectrum. The extracted total cross section is also in much better agreement with this model. Our new measurement puts useful constraints for the existence of the conjectured dibaryon resonance at mass M similar to 2.38 GeV and with width Gamma similar to 70 MeV.
Permanent Link: http://hdl.handle.net/11104/0254729