Measurement of the quasi freenp→npπ+π−andnp→ppπ−π0reactions at 1.25 GeV With HADES

A Kurilkin,J Pietraszko,C Behnke,J Markert,R Holzmann,T Kunz,S Harabasz,H Kuc,A Dybczak,J Michel,L Maier,J Friese,D González-Díaz,V Wagner,M Böhmer,V Pechenov,S Spataro,P Bordalo,A Lebedev,C Müntz,I Fröhlich,M Gumberidze,R Lalik,G Kornakov,C Höhne,E T Atomssa,L Lopes,J Siebenson,B W Kolb,L Naumann,A Tarantola,A Blanco,S Yurevich,H Schuldes,J Wüstenfeld,V Metag,T Scheib,P Sellheim,K Kardan,P Strzempek,A Sadovsky,A Ivashkin,O Pechenova,P Salabura,B Ramstein,H Ströbele,A Rost,J C Berger-Chen,M Traxler,T Hennino,T Galatyuk,C Deveaux,A Krása,H Tsertos,A Rustamov,K Teilab,O Svoboda,A Mangiarotti,C Wendisch,Yu G Sobolev,J A Garzón,P Fonte,Η Krebs ,L Silva,P Tlustý ,A Belyaev,W Przygoda,E Epple,M Pałka ,K Gill,Christian Sturm ,I Köenig ,F Křížek ,A Kurepin,A Reshetin,J Wirth,M Lorenz,L Rehnisch,K R Schmidt-Sommerfeld ,O Fateev,M Golubeva,B Kämpfer,T Karavicheva,V Petousis ,F Guber,S Lang,L Fabbietti,C Franco,W Koenig,J Biernat,O Arnold,V P Ladygin ,M Jurkovič ,Y Zanevsky,C Blume,A Ierusalimov,J Stroth,Robert Helmut Münzer ,P K Kurilkin ,K Lapidus,А Куглер ,R Kötte ,T Vasiliev,S Chernenko,G Korcyl

doi:10.1051/epjconf/20148102009

Abstract

We present the results of two-pion production in tagged quasi-free np collisions at a deutron incident beam energy of 1.25 GeV/c measured with the High-Acceptance Di-Electron Spectrometer (HADES) installed at GSI. The specific acceptance of HADES allowed for the first time to obtain high-precision data on π+π− and π−π0 production in np collisions in a region corresponding to large transverse momenta of the secondary particles. The obtained differential cross section data provide strong constraints on the production mechanisms and on the various baryon resonance contributions (∆∆, N(1440), N(1520), ∆(1600)). The invariant mass and angular distributions from the np → npπ+π −and np → ppπ−π0 reactions are compared with different theoretical model predictions.

Highlights

The two-pion production in nucleon-nucleon (NN) collisions is a very rich source of information about the baryon excitation spectrum and the baryon-baryon interaction properties
In this work we present high statistics invariant mass and angular distributions on π+π− and π−π0 production in quasi-free np collisions at an incident deutron beam energy of 1.25 GeV/c obtained with the High-Acceptance Di-Electron Spectrometer (HADES) spectrometer
The calculations [3] and [12] predict that the ππ production for the np → npπ+π− reaction at 1.25 GeV is mainly caused by the ΔΔ excitation, while according to the OPER model [11] the ΔΔ and OBE gives commensurable contributions

Summary

Introduction

The two-pion production in nucleon-nucleon (NN) collisions is a very rich source of information about the baryon excitation spectrum and the baryon-baryon interaction properties. In this work we present high statistics invariant mass and angular distributions on π+π− and π−π0 production in quasi-free np collisions at an incident deutron beam energy of 1.25 GeV/c obtained with the HADES spectrometer. The experimental data have been obtained using the High Acceptance Di-Electron Spectrometer (HADES) [9] located at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany.

Results

Conclusion