Space- and time-like form factors for $\omega\to\pi\gamma^*$ and $K^*\to K\gamma^*$ in light-front quark model

TL;DR

This paper uses a light-front quark model to calculate and analyze the space- and time-like form factors for specific meson decays, showing good agreement with experimental data and revealing a zero in the charged kaon form factor.

Contribution

It introduces a method to compute meson decay form factors in both space- and time-like regions using the light-front quark model constrained by a variational principle.

Findings

Predicted time-like form factor $F_{\omega o\pi}(q^2)$ matches experimental data.

Found a zero in the space-like form factor $F_{K^{*\pm}K^{\pm}}(Q^2)$ due to interference effects.

Successfully analytically continued form factors from space-like to time-like regions.

Abstract

We investigate space- and time-like form factors for $\omega\to\pi\gamma^*$ and $K^*\to K\gamma^*$ decays using the light-front quark model constrained by the variational principle for the QCD-motivated effective Hamiltonian. The momentum dependent space-like form factors are obtained in the $q^+=0$ frame and then analytically continued to the time-like region. Our prediction for the time-like form factor $F_{\omega\pi}(q^2)$ is in good agreement with the experimental data. We also find that the space-like form factor $F_{K^{*\pm}K^{\pm}}(Q^2)$ for charged kaons encounters a zero because of the negative interference between the two currents to the quark and the antiquark.