Spacelike and timelike form factors forω→πγ*andK*→Kγ*in the light-front quark model

Abstract

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