Single-pion production in proton-proton collisions at 1.25 GeV: measurements by HADES and a PWA

Witold Przygoda

doi:10.1051/epjconf/20148102014

Abstract

We report on the single-pion production in proton-proton collisions at a kinetic energy of 1.25 GeV based on data measured with HADES. Exclusive channels npπ + and ppπ 0 were studied simultaneously. The parametrization of production cross sections of the one-pion final states by means of the resonance model has been obtained. Inde- pendently, the extraction of the leading partial waves in the data were analyzed within the framework of the partial wave analysis (PWA). Contributions for the production of Δ(1232) and N(1440) intermediate states have been deduced.

Highlights

We report on the single-pion production in proton-proton collisions at a kinetic energy of 1.25 GeV based on data measured with High-Acceptance Di-Electron Spectrometer (HADES)
Our data are compared with results of a resonance model approach and a partial wave analysis (PWA)
To describe the data the resonance model of Teis et al [3] was implemented. It incorporates the one-pion exchange (OPE) model by Dmitriev and Sushkov [5] which assumes a dominance of the one-pion exchange contribution to the inelastic amplitude

Summary

Introduction

We report on the single-pion production in proton-proton collisions at a kinetic energy of 1.25 GeV based on data measured with HADES. Only the P33 partial wave was taken into account in the intermediate πN channel and pole diagram matrix elements were calculated using a form factor function with the cut-off parameter Λπ = 0.75 obtained by fitting the HADES data. Thanks to good acceptance coverage in the npπ+ channel the data were corrected by means of a 2-dimensional (cosθCpπM+ vs Mipnπv+ ) acceptance and efficiency correction matrix resulting in the cross section of 16.5 ± 2.0 mb (which is 85% of a resonance model prediction, see Fig. 1 left - open squares).

Results

Conclusion