Lattice Calculation of Light Meson Radiative Leptonic Decays
Physics Department, Brookhaven National Laboratory（布鲁克海文国家实验室物理系）；School of Physics and Astronomy, The University of Edinburgh（爱丁堡大学物理与天文学院）；Physics Department, Columbia University（哥伦比亚大学物理系）；School of Physics, Peking University（北京大学物理学院）；Collaborative Innovation Center of Quantum Matter（量子物质协同创新中心）；Center for High Energy Physics, Peking University（北京大学高能物理中心）；RIKEN-BNL Research Center, Brookhaven National Laboratory（布鲁克海文国家实验室理研-BNL研究中心）；Physics Department, University of Connecticut（康涅狄格大学物理系）；School of Physics and Astronomy, University of Southampton（南安普顿大学物理与天文学院）
Peter Boyle, Norman H. Christ, Xu Feng, Taku Izubuchi, Luchang Jin, Christopher T. Sachrajda, Xin-Yu Tuo
In this work, we perform a lattice QCD calculation of the branching ratios and the form factors of radiative leptonic decays $P \to \ell ν_\ell γ$ ($P = π, K$) using $N_f=2+1$ domain wall fermion ensembles generated by the RBC and UKQCD collaborations at the physical pion mass. We adopt the infinite volume reconstruction (IVR) method, which extends lattice data to infinite volume and effectively controls the finite volume effects. This study represents a first step toward a complete calculation of radiative corrections to leptonic decays using the IVR method, including both real photon emissions and virtual photon loops. For decays involving a final state electron, collinear radiative corrections, enhanced by the large logarithmic factors such as $\ln(m_π^2/m_e^2)$ and $\ln(m_K^2/m_e^2)$, can reach the level of $O(10\%)$ and are essential at the current level of theoretical and experimental precision. After including these corrections, our result for $π\to eν_eγ$ agrees with the PIBETA measurement; for \(K \to eν_eγ\), our results are consistent with the KLOE data and exhibit a $1.7σ$ tension with E36; and for $K \to μν_μγ$, where radiative corrections are negligible, our results confirm the previously observed discrepancies between lattice results and the ISTRA/OKA measurements at large photon energies, and with the E787 results at large muon photon angles.
Inclusive semi-leptonic B meson decay structure functions from lattice QCD
本文提出了一种非微扰计算包含半轻子B介子衰变的前向散射矩阵元的方法。通过对四点关联函数的格点量子色动力学计算，可以得到相应的强子非物理运动学结构函数。非物理运动学点可由物理微分衰减率解析延拓得到。在零反冲极限下，对B_s -> X_c l nu模进行了数值检验。我们使用2+1动力学夸克味产生的晶格系综。价粲夸克的质量被调谐到它的物理值，而底夸克的质量在（1.56-2.44）mc范围内变化。从数值结果中我们可以看出基态D_s^（*）介子的贡献以及激发态和连续态的贡献。
Leptonic Decays of Charged Pseudoscalar Mesons - 2015
本文综述了$π^\pm$、$K^\pm$、$D^{\pm}$、$D_s^\pm$和$B^\pm$赝标介子的纯轻子衰变物理。所测得的衰变率与组分夸克的相关弱相互作用CKM矩阵元和与介子中夸克和反夸克波函数重叠相关的强相互作用参数（称为衰变常数$f_P$）的乘积有关。用{ \it ab initio}格点QCD模拟方法，可以得到$π^\pm$、$K^\pm$、$D^{\pm}$、$D_s^\pm$和$B^\pm$介子的轻子衰变常数，理论不确定度可控，计算精度高.实验轻子衰变率测量和理论衰变常数计算相结合，使几个元素的CKM矩阵内的标准模型的确定。这些测定与半轻子衰变的结果是竞争性的，也是互补的，因为它们对不同的夸克变味电流敏感。它们也可以用来测试CKM矩阵的第一行和第二行的酉性。相反地，采用由么正性预测的CKM元素，可以推断出$f_P$的“实验”值，其可以与理论进行比较。这些提供了格点QCD方法的测试，假设新物理对轻子衰变的贡献在当前的精度水平上可以忽略不计。这篇评论是粒子数据组2016年版文章的基础，更新了参考文献中的版本。[1-3]中所述。
