标题： 大$q^{2}$时$B_{s}\to μ^{+}μ^{-}γ$的衰变率来自格点 QCD 显示英文标题

标题： The $B_{s}\to μ^{+}μ^{-}γ$ decay rate at large $q^{2}$ from lattice QCD

摘要： 我们通过格点QCD计算确定描述$B_{s}\to \mu^{+}\mu^{-}\gamma$衰变的局部形式因子。 对于此分析，我们使用ETM合作组产生的规范配置，采用最大扭曲下的$N_{f}=2+1+1$种味的Wilson-Clover扭曲质量费米子。 为了获得$B_{s}$介子的形式因子，我们对几个重-奇夸克介子质量$m_{H_{s}}$在范围$m_{H_{s}} \in [ m_{D_{s}}, 2 m_{D_{s}} ]$内进行模拟，并利用HQET标度定律外推到物理的$B_{s}$介子点$m_{B_{s}}\simeq 5.367~{\rm GeV}$。 我们覆盖大二Muon不变质量区域$\sqrt{q^{2}} > 4.16\,{\rm GeV}$，并利用我们的结果确定$B_{s}\to \mu^{+}\mu^{-}\gamma$的分支比，该分支比最近由LHCb在区域$\sqrt{q^{2}} > 4.9\,{\rm GeV}$中测量。 在$\sqrt{q^{2}} < 4.8\,{\rm GeV}$值处的部分分支比的不确定性中，最大的贡献现在来自于共振和其他长距离效应，包括来自“魅夸克penguins”的效应，我们通过求和$J_P=1^-$朱子能级共振的贡献来估计这些效应。 显示英文摘要

摘要： We determine, by means of lattice QCD calculations, the local form factors describing the $B_{s}\to \mu^{+}\mu^{-}\gamma$ decay. For this analysis we make use of the gauge configurations produced by the ETM Collaboration with $N_{f}=2+1+1$ flavour of Wilson-Clover twisted-mass fermions at maximal twist. To obtain the $B_{s}$ meson form-factors, we perform simulations for several heavy-strange meson masses $m_{H_{s}}$ in the range $m_{H_{s}} \in [ m_{D_{s}}, 2 m_{D_{s}} ]$, and extrapolate to the physical $B_{s}$ meson point $m_{B_{s}}\simeq 5.367~{\rm GeV}$ making use of the HQET scaling laws. We cover the region of large di-muon invariant masses $\sqrt{q^{2}} > 4.16\,{\rm GeV}$, and use our results to determine the branching fraction for $B_{s}\to \mu^{+}\mu^{-}\gamma$, which has been recently measured by LHCb in the region $\sqrt{q^{2}} > 4.9\,{\rm GeV}$. The largest contribution to the uncertainty in the partial branching fractions at values of $\sqrt{q^{2}} < 4.8\,{\rm GeV}$ is now due to resonance and other long-distance effects, including those from "charming penguins", which we estimate by summing over the contributions from the $J_P=1^-$ charmonium resonances.