论文标题
在$ \ bar {b} \ to \ bar {k} \ ell^+ \ ell^ - $ in Double-dirdferential级别中的QED校正
QED Corrections in $\bar{B} \to \bar{K} \ell^+ \ell^-$ at the Double-Differential Level
论文作者
论文摘要
我们将QED更正的详细分析列为$ \ bar {b} \ to \ bar {k} \ ell^+ \ ell^ - $ $ $在双分化级别上衰减。使用相空间切片方法在分析上证明了软和共线差异的取消。虽然发现软差可以在差分级别取消，但除了光子含量外，还需要取消硬线性日志$ \ ln m_ \ ell $，这是运动变量的特定选择。特别是，在Lepton-Pair不变质量分布（$ Q^2 $）中的硬性日志很大，并且在与实验进行比较时需要谨慎处理。使用有效的介体拉格朗日评估虚拟和真实振幅。至关重要的是，我们表明，超越这种近似不会引入任何进一步的红外敏感术语。所有分析计算均用于通用电荷，因此适应半衰减的衰减，例如$ b \ to d \ ell \barν$。
We present a detailed analysis of QED corrections to $\bar{B} \to \bar{K} \ell^+ \ell^-$ decays at the double-differential level. Cancellations of soft and collinear divergences are demonstrated analytically using the phase space slicing method. Whereas soft divergences are found to cancel at the differential level, the cancellation of the hard-collinear logs $\ln m_\ell$ require, besides photon-inclusiveness, a specific choice of kinematic variables. In particular, hard-collinear logs in the lepton-pair invariant mass distribution ($q^2$), are sizeable and need to be treated with care when comparing with experiment. Virtual and real amplitudes are evaluated using an effective mesonic Lagrangian. Crucially, we show that going beyond this approximation does not introduce any further infrared sensitive terms. All analytic computations are performed for generic charges and are therefore adaptable to semileptonic decays such as $B \to D \ell \bar ν$.
