Mixing effects in radiative decays of heavy-strange axial-vector mesons within light-cone QCD sum rules

Abstract

We calculate the radiative decay widths of $D_{s1}(2460)\to D_s\gamma$, $D_{s1}(2536)\to D_s\gamma$, $B_{s1}(5750)\to B_s\gamma$, and $B_{s1}(5830)\to B_s\gamma$ within light-cone QCD sum rules, taking into account the mixing between the ${}^1{P}_1$ and ${}^3{P}_1$ configurations. In the bottom-strange sector, we consider the experimentally established $B_{s1}(5830)$ together with the theoretically expected lower $1^{+}$ state, denoted $B_{s1}(5750)$. We obtain $\Gamma [D_{s1}(2460)\to D_s\gamma ]=45.9_{-8.5}^{+10.1}$ keV, $\Gamma [D_{s1}(2536)\to D_s\gamma ]=0.55_{-0.48}^{+1.73}$ keV, $\Gamma [B_{s1}(5750)\to B_s\gamma ]=12.0_{-2.3}^{+2.9}$ keV, and $\Gamma [B_{s1}(5830)\to B_s\gamma ]=8.9_{-2.0}^{+2.4}$ keV. The $D_{s1}(2460)\to D_s\gamma$ decay width is substantially larger than that of $D_{s1}(2536)\to D_s\gamma$. This difference originates from ${}^1{P}_1$-${}^3{P}_1$ mixing: the two basis-current contributions interfere constructively for the lower state and destructively for the higher state. In the bottom-strange sector, the two widths are comparable within their uncertainties, although the higher state still exhibits destructive interference. These results show that the radiative decay pattern of strange heavy axial-vector mesons is sensitive to the mixing of the two spin configurations.