Low-energy pion-pion scattering in the $pp \to pp\pi^{+}\pi^{-}$ and $p\bar p \to p\bar p\pi^{+}\pi^{-}$ reactions

TL;DR

This paper investigates the role of pion-pion rescattering in specific proton-proton and proton-antiproton reactions, finding it negligible near threshold and providing predictions for future experiments with detailed differential distributions.

Contribution

It presents a detailed evaluation of pion-pion rescattering effects in these reactions and offers predictions for upcoming experiments, including methods to suppress dominant resonance mechanisms.

Findings

Pion-pion rescattering contribution is negligible near threshold.

Provides differential distribution predictions for future experiments.

Discusses methods to suppress resonance mechanisms.

Abstract

We evaluate the contribution of pion-pion rescattering to the $p p \to p p \pi^+ \pi^-$ and $p \bar p \to p \bar p \pi^+ \pi^-$ reactions. We compare our results with the close-to-threshold experimental data. The pion-pion rescattering contribution is found there to be negligible. The predictions for future experiments with PANDA detector at High Energy Storage Ring (HESR) in GSI Darmstadt are presented. It is discussed how to cut off the dominant Roper resonance and double-$\Delta$ excitation mechanisms leading to the $p p \pi^+ \pi^-$ channel in final state. Differential distributions in momentum transfers, transverse momentum, effective two-pions mass, relative azimuthal angle between pions, and pion rapidities are presented.