Test of FSR in the process $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ at DA$\Phi$NE

Abstract

In this paper we consider the possibility to test the FSR model in the reaction $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ at DA$\Phi$NE. We propose to consider the low $Q^2$ region ($Q^2$ is the invariant mass squared of the di-pion system) to study the different models describing $gamm{a}^{\ast }\to {\pi }^{+}{\pi }^{-}\gamma$ interaction. As illustration we compare the scalar QED and Resonance Perturbation Theory prediction for the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ cross section. We also consider the contribution coming from the $\varphi$ direct decay ($\varphi \to {\pi }^{+}{\pi }^{-}\gamma$). We find the low $Q^2$ region is sensitive to FSR models.

7 pages, 4 figures, talk at EURIDICE Midterm Collaboration Meeting, Frascati, 8-12 February