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

TL;DR

This study investigates how the $K^*$ meson's magnetic dipole moment influences the $e^+e^- o K^+ K^- o ext{2}\pi^0$ cross section, using BaBar data and a vector meson dominance model.

Contribution

It provides the first data-driven estimate and bounds for the $K^*$ meson's magnetic dipole moment based on experimental cross section data.

Findings

Sensitivity of the cross section to the $K^*$ MDM demonstrated.

Estimated $K^*$ MDM central value is 4.5 in units of $e/2 m_{K^*}$.

Upper bound for the $K^*$ MDM is 6.3 in the same units.

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.