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 $D_{s1}(2460)\to D_sγ$, $D_{s1}(2536)\to D_sγ$, $B_{s1}(5750)\to B_sγ$, and $B_{s1}(5830)\to B_sγ$ 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 $Γ[D_{s1}(2460)\to D_sγ]=45.9^{+10.1}_{-8.5}$ keV, $Γ[D_{s1}(2536)\to D_sγ]=0.55^{+1.73}_{-0.48}$ keV, $Γ[B_{s1}(5750)\to B_sγ]=12.0^{+2.9}_{-2.3}$ keV, and $Γ[B_{s1}(5830)\to B_sγ]=8.9^{+2.4}_{-2.0}$ keV. The $D_{s1}(2460)\to D_sγ$ decay width is substantially larger than that of $D_{s1}(2536)\to D_sγ$. 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.