论文标题
在符合符号依赖的nnlo校正上b-> xs伽马
On charm-mass dependent NNLO corrections to B -> Xs gamma
论文作者
论文摘要
已知B Meson的包容性辐射衰减可在标准模型的许多流行扩展中提供强大的限制。这些限制在于至关重要的取决于标准模型预测的精度。对理论不确定性的主要贡献之一是由于某些近代到领先的顺序QCD校正QCD校正，其在物理魅力夸克质量质量m_c的值是使用m_c = 0和m_c >> m_b限制之间的插值估算的。在M_C的物理值中直接确定此类校正需要计算数百个具有单位性削减的两尺度的四环传播器图。应用按零件的集成方法，我们用主积分来表达校正。这些积分在M_C >> M_B上的渐近扩展是正在求解的Z = M_C^2/M_B^2中微分方程的边界条件。在这里，我们介绍了涉及Gluon线上无质量和巨大费米循环的图表的最终结果。对于两体削减，我们确认文献中已经存在的分析表达式和/或数值拟合。在四体情况下，我们通过包括以前仅在M_C中使用插值估算的几张图来完成校正。我们还报告了剩余图的持续计算的状态，在该图中没有封闭的fermion循环存在。
The inclusive radiative decay of the B meson is known to provide strong constraints on many popular extensions of the Standard Model. Such constraints crucially depend on precision of the Standard Model predictions. One of the main contributions to the theoretical uncertainty is due to certain Next-to-Next-to-Leading Order QCD corrections whose values at the physical charm quark mass m_c have been estimated using interpolation between the m_c=0 and m_c >> m_b limits. A direct determination of such corrections at the physical value of m_c requires calculating hundreds of two-scale four-loop propagator diagrams with unitarity cuts. Applying the integration-by-parts method, we express the corrections in terms of master integrals. Asymptotic expansions of these integrals at m_c >> m_b serve as boundary conditions for differential equations in z=m_c^2/m_b^2 that are being numerically solved. Here, we present our final results for the diagrams involving massless and massive fermion loops on the gluon lines. For the two-body cuts, we confirm the analytical expressions and/or numerical fits that are already present in the literature. In the four-body case, we make the correction complete by including several diagrams that have previously been only estimated using interpolation in m_c. We also report the status of the ongoing calculation of the remaining diagrams where no closed fermion loops on the gluon lines are present.
