AI 中文总结
该研究更新了标准模型对$\bar B \to X_s \boldsymbol{\text{γ}}$衰变的预言，完成了其QCD次领头阶领头幂次计算，消除了粲夸克质量插值的$\boldsymbol{\text{±3%}}$不确定性，所得分支比与实验平均值吻合。
AI 中文摘要
我们报告了关于遍举辐射衰变$\bar B\to X_s \boldsymbol{\text{γ}}$的两项最新计算，具体包括：次领头阶（NLO）下的多部分子贡献，以及针对粲夸克质量物理值的次-次领头阶（NNLO）下$Q_{1,2}-Q_7$干涉项。前者从形式上完成了QCD中领头幂次下$\bar{B} \rightarrow X_s \boldsymbol{\text{γ}}$的次领头阶计算；后者消除了因粲夸克质量$m_c$插值导致的长期存在的$\boldsymbol{\text{±3%}}$不确定性。更新后的标准模型预言，对于B介子静止系中光子能量$E_\boldsymbol{\text{γ}} > 1.6\boldsymbol{\text{GeV}}$、CP及同位旋平均的分支比为$\boldsymbol{\text{Br}}_{s \boldsymbol{\text{γ}}}^{\boldsymbol{\text{SM}}} = (3.54 \boldsymbol{\text{±}} 0.14)\boldsymbol{\text{×}} 10^{-4}$，该值与当前实验平均值$\boldsymbol{\text{Br}}_{s \boldsymbol{\text{γ}}}^{\boldsymbol{\text{exp}}} = (3.49 \boldsymbol{\text{±}} 0.19)\boldsymbol{\text{×}} 10^{-4}$吻合良好。
英文摘要
We report on two recent calculations on the inclusive radiative decay $\bar B\to X_s γ$, notably multi-parton contributions at NLO and the $Q_{1,2}-Q_7$ interference at NNLO for the physical value of the charm-quark mass. The former calculation formally completes $\bar{B} \rightarrow X_s γ$ at NLO in QCD at leading power, the latter removes a long-standing $\pm 3\%$ uncertainty arising from interpolation in $m_c$. The updated Standard-Model prediction for the CP- and isospin-averaged branching ratio reads ${\mathcal B}_{s γ}^{\rm SM} = (3.54 \pm 0.14)\times 10^{-4}$ for photon energies $E_γ> 1.6\,{\rm GeV}$ in the $B$-meson rest frame. This value is in good agreement with the current experimental average ${\mathcal B}_{s γ}^{\rm exp} = (3.49 \pm 0.19)\times 10^{-4}$.
Comments13 pages, 6 figures, 1 table. Contribution to the proceedings of "Loops and Legs in Quantum Field Theory (LL2026), 12-17, April, 2026, Bayreuth, Germany"
