我们发展了一种计算硬过程中的靶质量和有限t=(p '-p)^2修正的一般方法,这种硬过程可以在算子乘积展开的框架内研究,并涉及到从强子初态到末态的动量转移。这样的修正,通常被称为运动学的,可以被定义为所有扭转的算子的贡献,可以减少到总的领导扭转算子的导数。作为主要的结果,我们提供了一组投影算子,拿起“运动”的一部分,一个任意的味道非单扭四QCD运营商。一个完整的表达式推导出的两个电磁电流的时间顺序的产品,包括所有的运动学修正扭曲四精度。所得结果可直接应用于深虚康普顿散射、跃迁γ ^*-> M γ形状因子及相关过程的研究。作为这项研究的副产品,我们发现了一系列“真正的”扭曲四味非单线态夸克-反夸克-胶子运营商具有相同的反常尺寸的领导扭曲夸克-反夸克运营商。
英文摘要:
We develop a general approach to the calculation of target mass and finite t=(p'-p)^2 corrections in hard processes which can be studied in the framework of the operator product expansion and involve momentum transfer from the initial to the final hadron state. Such corrections, which are usually referred to as kinematic, can be defined as contributions of operators of all twists that can be reduced to total derivatives of the leading twist operators. As the principal result, we provide a set of projection operators that pick up the "kinematic" part of an arbitrary flavor-nonsinglet twist-four operator in QCD. A complete expression is derived for the time-ordered product of two electromagnetic currents that includes all kinematic corrections to twist-four accuracy. The results are immediately applicable to the studies of deeply-virtual Compton scattering, transition gamma^*-> M gamma form factors and related processes. As a byproduct of this study, we find a series of "genuine" twist-four flavor-nonsinglet quark-antiquark-gluon operators which have the same anomalous dimensions as the leading twist quark-antiquark operators.
The forward-backward asymmetry and differences of partial moments in inclusive semileptonic B decays
对包含半轻子$B\rightarrow X_c l ν_l$中测得的运动学分布的矩进行全局拟合,使得能够确定Cabibbo-Kobayashi-Maskawa矩阵元$|V_{cb}|$以及重夸克展开的非微扰矩阵元。在当前的拟合中,仅采用两种不同的运动学分布,因此,需要考虑这些分布的较高矩来提取相关的非微扰矩阵元素。一个给定的分布的时刻是高度相关的,实验的不确定性增加更高的时刻。为了解决这些问题,Turczyk建议在全局拟合中加入带电轻子前后不对称性$\mathcal{A}_{FB}$,因为它提供了常用矩之外的非微扰参数的信息。这是可能的构造运动分布的部分矩的差异,它可以提供额外的信息的非微扰参数以外的$\mathcal{A}_{FB}$,并在这项工作中首次进行了研究。此外,实验削减四动量转移平方研究,并保持角分布的形状,在常用的轻子能量削减。最后,讨论了末态辐射和实验轻子识别要求对$\mathcal{A}_{FB}$测量和偏矩差的影响。
Improved Regge Kinematics and All-Path-Length Corrections to Momentum Broadening in the Quark-Gluon Plasma
School of Physics, University of the Witwatersrand(威特沃特斯兰德大学物理学院);Mandelstam Institute for Theoretical Physics (MITP), University of the Witwatersrand(威特沃特斯兰德大学曼德尔斯坦理论物理研究所);National Institute for Theoretical and Computational Sciences (NITheCS)(理论与计算科学国家研究所)