Charge asymmetry in $e^+e^-\to \pi^+\pi^-$ process

TL;DR

This paper investigates the charge asymmetry in the $e^+e^- o \pi^+\pi^-$ process, identifying the source of previous discrepancies and proposing a more accurate model that aligns well with experimental observations.

Contribution

The authors introduce a more realistic model of pion structure in two-photon exchange calculations, resolving prior theoretical-experimental discrepancies.

Findings

Improved agreement between theory and experiment

Identification of pion structure effects in charge asymmetry

Enhanced understanding of two-photon exchange contributions

Abstract

We consider the charge asymmetry in the differential cross section of the process $e^+e^- \rightarrow \pi^+\pi^-$. Experimental data show large deviations from the results of the available theoretical calculations. Motivated by this fact, we revisit the contribution of the two photon exchange diagrams and find the origin of discrepancy in an oversimplified account of the pion internal structure in the theoretical calculations. We present a natural and simple approach that accounts for the pion structure in a more consistent way and find remarkable agreement with the experimental data.