Effect of $K^*$ meson magnetic dipole moment on the $e^+e^- \to K^+ K^-\pi^0 \pi^0 $ cross section

Abstract

We explore the sensitivity of the $e^{+} e^{-} \to K^+ K^- 2 \pi^0$ cross section to the magnetic dipole moment (MDM) of the $K^*$ vector meson. We describe the $\gamma^* \to 2K2\pi$ vertex using a vector meson dominance model, including the intermediate resonant contributions relevant for energies below 2.4 GeV. Using BaBar data for this process, we show that this observable is indeed sensitive to the MDM of the $K^*$; we obtain a central value for the MDM of $\mu_{K^*}=4.5$ and an upper bound of $\bar{\mu}_{K^*} = 6.3$, in units of $e/2 m_{K^*}$. We emphasize the need for higher precision data to provide a first data-driven determination of this parameter to confront it with theoretical predictions.