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

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.