A study of $\rho -\omega$ mixing in resonance chiral theory

Abstract

The strong and electromagnetic corrections to $\rho -\omega$ mixing are calculated using a SU(2) version of resonance chiral theory up to next-to-leading orders in $1/N_C$ expansion, respectively. Up to our accuracy, the effect of the momentum dependence of $\rho -\omega$ mixing is incorporated due to the inclusion of loop contributions. We analyze the impact of $\rho -\omega$ mixing on the pion vector form factor by performing numerical fit to the data extracted from $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ and $\tau \to {\nu }_{\tau }2\pi$, while the decay width of $\omega \to {\pi }^{+}{\pi }^{-}$ is taken into account as a constraint. It is found that the momentum dependence is significant in a good description of the experimental data. In addition, based on the fitted values of the involved parameters, we analyze the decay width of $\omega \to {\pi }^{+}{\pi }^{-}$, which turns out to be highly dominated by the $\rho -\omega$ mixing effect.

Comments: 10 pages, 4 figures. References added