Within the framework of chiral effective field theory, we study various electromagnetic processes with light vector resonances: $K^{ \ast}(892)\to K\gamma$, $e^{ +}e^{ -}\to K^{ \ast}(892)K $ and the $\omega\pi\gamma^\ast$ form factors. With two multiplets of vector resonances being introduced, we fit the decay widths of $K^{ \ast0}\to K^{ 0}\gamma$, $K^{ \ast+}\to K^{ +}\gamma$, and the pertinent measurements from the $e^{ +}e^{ -}\to K^{ \ast \pm}(892)K^{ \mp} $ cross sections, such as moduli and relative phases between the isoscalar and isovector components from BABAR collaboration, together with the $\omega\pi$ form factors from NA60, SND and CLEO collaborations. The values of resonance couplings, masses and widths of the excited vector states $\rho'$ and $\phi'$ are then determined. The $\omega'$-$\phi'$ mixing angle is discussed and turns out to be quite different from the ideal mixing case. Three sources of $SU(3)$ symmetry breaking effects in the $\Gamma(K^{ \ast}\to K\gamma)$ decays are identified and analyzed in detail.
Categories: hep-ph hep-ex