Reaction pp-> {pp}_s pi^0 in the GeV region and pi^0 p rescattering

TL;DR

This paper analyzes proton-proton to proton-proton pi-zero reactions in the GeV energy range using a one-pion exchange model, explaining some features of the cross section but underpredicting higher energy maxima.

Contribution

It applies a one-pion exchange model to new COSY data, providing insights into the reaction mechanism and pion-proton rescattering effects in this energy region.

Findings

Broad maximum at 0.5-1.4 GeV explained by isospin 3/2 contribution

Model successfully describes low-energy peak but underpredicts the 2 GeV maximum

Highlights the importance of pi^0 p rescattering in the reaction

Abstract

COSY data on the cross section of the reaction pp -> {pp}_s pi^0, where {pp}_s is the proton pair in the 1S0 state at small excitation energy E_{pp}=0-3 MeV, recently obtained for beam energies 0.5 - 2.0 GeV are analyzed within the one-pion exchange model. The model is based on the subprocess pi^0 p -> pi^0 p and final state pp-interaction. A broad maximum observed in the energy dependence of the cross section at 0.5 - 1.4 GeV in the forward direction is explained by this model as a dominant contribution of the isospin 3/2 in the pi^0 p-rescattering. The second maximum observed at 2 GeV is underpredicted within the model by one order of magnitude.