We compute the (three) master integrals for the crossed ladder diagram with two exchanged quanta of equal mass. The differential equations obeyed by the master integrals are used to generate power series expansions centered around all the singular (plus some regular) points, which are then matched numerically with high accuracy. The expansions allow a fast and precise numerical calculation of the three master integrals (better than 15 digits with less than 30 terms in the whole real axis). A conspicuous relation with the equal-mass sunrise in two dimensions is found. Comparison with a previous large momentum expansion is made finding complete agreement.
We present an evaluation of the two master integrals for the crossed vertex diagram with a closed loop of top quarks that allows for an easy numerical implementation. The differential equations obeyed by the master integrals are used to generate power series expansions centered around all the singular points. The different series are then matched numerically with high accuracy in intermediate points. The expansions allow a fast and precise numerical calculation of the two master integrals in all the regions of the phase space. A numerical routine that implements these expansions is presented.
Calculation of tensor susceptibility beyond rainbow-ladder approximation of Dyson-Schwinger equations approach
本文推广了[Y. M. Shi，K. P. Wu，W. M. Sun，H. S. Zong，J. L. Ping，Phys. Lett. B $\bf{639}$，248（2006）]的方法与采用Ball-Chiu（BC）顶点的方法相比。研究了夸克胶子顶点的修饰效应对张量真空磁化率的影响。结果表明，与彩虹梯近似值相比，在BC顶点近似下得到的张量真空磁化率降低了约10%。这说明在DS方法中计算张量真空磁化率时，夸克胶子顶点的修饰效应并不大。
We perform a complete calculation of electron-seeded pair-creation (the trident process) in a constant crossed electromagnetic background. Unlike earlier treatments, we include the interference between exchange diagrams. We find this exchange interference can be written as a contribution solely to the one-step process, and for small quantum nonlinearity parameter is of the same order as other one-step terms. We find the exchange interference further suppresses the one-step process in this parameter regime. Our findings further support the crucial assumption made in laser-plasma simulation code…
We compute the general expression of the one-loop vertex correction in an arbitrary plane-wave background field for the case of two on-shell external electrons and an off-shell external photon. The properties of the vertex corrections under gauge transformations of the plane-wave background field and of the radiation field are studied. Concerning the divergences of the vertex correction, the infrared one is cured by assigning a finite mass to the photon, whereas the ultraviolet one is shown to be renormalized exactly as in vacuum. Finally, the corresponding expression of the vertex correction …
A previously proposed all-loop-orders relation between the Regge limits of four-point amplitudes of N=4 supersymmetric Yang-Mills theory and N=8 supergravity is established at the three-loop level. We show that the Regge limit of known expressions for the amplitudes obtained using generalized unitarity simplifies in both cases to a (modified) sum over three-loop ladder and crossed-ladder scalar diagrams. This in turn is consistent with the result obtained using the eikonal representation of the four-point gravity amplitude. A possible exact three-loop relation between four-point amplitudes is …
Z-gamma-Higgs vertex effects in Higgs production at future e-gamma linear colliders
通过（e γ-> e H）过程研究了在未来加速器中电子-光子碰撞中希格斯玻色子玻色子的单圈产生，对于中等质量的希格斯粒子.精确的截面，包括纵向偏振的初始光束的可能性，提出。在能量范围为$\sqrt{s}=(0.5-2)$ TeV的情况下，重新计算了以前在Weizsäcker-Williams近似下所作的估计，发现它们比交叉过程（e e-> gamma H）的截面大两个数量级以上。我们发现，不仅（e gamma -> e H）具有与（gamma gamma -> H）过程类似的用于测试单圈gamma-gamma-H顶点的势，而且，通过要求在（e gamma -> e H）中以大角度标记的最终电子，（H e）产生也提供了测试Z-gamma-H顶点的极好方式。本文分析了末态电子被标记时（e γ-> e H -> e bb）过程的运动学分布，找到了控制主要不可约背景的策略，初态辐射效应被控制在几个百分点以内。
