Radiative transition processes of light vector resonances in a chiral framework

Within the framework of chiral effective field theory, we study various electromagnetic processes with light vector resonances: $K^{\ast}(892)\to Kγ$, $e^{+}e^{-}\to K^{\ast}(892)K$ and the $ωπγ^\ast$ form factors. With two multiplets of vector resonances being introduced, we fit the decay widths of $K^{\ast0}\to K^{0}γ$, $K^{\ast+}\to K^{+}γ$, 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 $ωπ$ form factors from NA60, SND and CLEO collaborations. The values of resonance couplings, masses and widths of the excited vector states $ρ'$ and $ϕ'$ are then determined. The $ω'$-$ϕ'$ 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 $Γ(K^{\ast}\to Kγ)$ decays are identified and analyzed in detail.

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