Partial wave analysis of HADES data for two-pion production in pion-nucleon reactions

I Ciepał,A V Sarantsev,W Przygoda

doi:10.1051/epjconf/201919902001

Abstract

Pion beams are perfect tools to probe resonance excitations at a fixed energy, thus properties of baryonic resonances and their coupling channels can be studied. The HADES Collaboration performed a systematic scan around the second resonance region at four different pion beam momenta 0.656, 0.69, 0.748 and 0.8 GeV/c in π− p reaction. The role of the N(1520) resonance in conjunction with the intermediate ρ-meson production has been studied in the framework of a partial wave analysis. Preliminary results on exclusive channels with one pion (π− p) and two pions (nπ+π− and pπ−π0) in the final state are presented.

Highlights

The experimental program of the High Acceptance Di-Electron Spectrometer (HADES) Collaboration covers the measurement of dielectron emission from a compressed baryonic matter formed in heavy ion collisions and in elementary nucleon–nucleon and pion–proton collisions [1]
The π− p elastic scattering has been reconstructed for all four pion beam momenta, and normalized in the θCπ−M range of 60◦ − 110◦ to the known world data (SAID database [8]), see Fig. 1, left panel
The absolute cross sections for π− p elastic scattering are presented in Fig. 1 for the two pion beam momenta, 656 and 800 MeV/c

Summary

Introduction

The experimental program of the HADES Collaboration covers the measurement of dielectron emission from a compressed baryonic matter formed in heavy ion collisions and in elementary nucleon–nucleon (np, pp) and pion–proton (πp) collisions [1]. Both objectives are complementary, the in-medium effects can be studied following the understanding of the production channels in the elementary reactions. A systematic energy scan and high precision data are needed [2]. The data have been included into the multichannel partial wave analysis (PWA), developed by the Bonn-Gatchina group [4]. The role of resonance-ρN coupling in the electromagnetic form factors of baryonic resonances are in focus of the on-going investigations [1, 5]

HADES detector and pion beamline

Results

Summary and outlook