# Charge asymmetries in e e-> pi pi- gamma at the phi resonance - High Energy Physics - Phenomenology

Abstract: We consider the forward-backward pion charge asymmetry for thee^{+}e^{-}\to\pi^{+}\pi^{-}\gamma process. At tree level we considerbremsstrahlung and double resonance contributions. Although the lattercontribution is formally sub-leading, it is enhanced at low dipion invariantmass due to $ho$ resonant effects. We consider also four alternative modelsto describe the final state radiation at the loop level: Resonance ChiralPerturbation Theory, Unitarized Chiral Perturbation Theory, Kaon Loop Model andLinear Sigma Model. The last three models yield results compatible withexperimental data. The Kaon Loop Model requires an energy dependent phase toachieve the agreement.

Author: A. Gallegos, J. L. Lucio, G. Moreno, M. Napsuciale

Source: https://arxiv.org/