We discuss two recent developments of the sector-improved residue subtraction scheme for handling real radiation at NNLO in QCD. We present a new phase space construction which minimizes the number phase space configurations for subtraction terms and we rederive the four-dimensional formulation of the scheme.
A new method for local subtraction at next-to-next-to-leading order in QCD is sketched, attempting to conjugate the minimal counterterm structure arising from a sector partition of the radiation phase space with the simplifications following from analytic integration of the counterterms.
We present a new method for the local subtraction of infrared divergences at next-to-next-to-leading order (NNLO) in QCD, for generic infrared-safe observables. Our method attempts to conjugate the minimal local counterterm structure arising from a sector partition of the radiation phase space with the simplifications following from analytic integration of the counterterms. In this first implementation, the method applies to final-state massless particles. We show how our method compactly organises infrared subtraction at NLO, we deduce in detail the general structure of the subtraction terms …
Within the framework of local analytic sector subtraction, we present the subtraction of next-to-leading-order QCD singularities for processes featuring massless coloured particles in the initial as well as in the final state. The features of the method are explained in detail, including the introduction of an optimisation procedure aiming at improving numerical stability at the cost of no extra analytic complexity. A numerical validation is provided for a variety of processes relevant to lepton as well as hadron colliders. This work constitutes a relevant step in view of the application of ou…
A novel subtraction scheme for double-real radiation at NNLO
本文导出了一个通用的减影方案STRIPPER(SecToR Improved Phase sPacE for real Radiation),用于计算双实辐射对末态至少有两个粒子处于首阶过程的次首阶(NNLO)QCD贡献。其结果是在维正则化的参数中的洛朗展开,其系数应通过数值蒙特卡罗积分来评估。两个主要的想法是一个两级分解的相空间,第二个因式分解的振幅的奇异极限,和一个合适的参数化的运动学允许推导的减法和集成减法项程函因子和分裂函数,而无需非平凡的解析积分。
Mixing of pseudoscalar-baryon and vector-baryon in the $J^P=1/2^-$ sector and the $N^*$(1535) and $N^*$(1650) resonances
采用$πN$,$ηN$,$KΛ$,$KΣ$,$ρN$和$πΔ$(d波)的耦合通道方案,利用隐规范拉格朗日量和赝标介子-重子与矢量介子-重子态的混合,研究了介子-重子与$J^P=1/2^-$的相互作用.我们将每个通道的减法常数拟合到从实验数据中提取的$πN$散射数据的$S_{11}$分波振幅。我们发现两个极点,我们与$N^*(1535)$和$N^*(1650)$共振,并表明减法常数都是负的,自然的大小。我们计算了每个共振的不同通道的分支比,我们发现一个很好的协议与实验数据。还评估了$π^- p \to ηn$散射的横截面并与实验进行了比较。
Within the framework of local analytic sector subtraction, we present the full analytic integration of double-real and real-virtual local infrared counterterms that enter NNLO QCD computations with any number of massless final-state partons. We show that a careful choice of phase-space mappings leads to simple analytic results, including non-singular terms, that can be obtained with conventional integration techniques.
We propose a new method of computing real emission contributions to hard QCD processes. Our approach uses sector decomposition of the exclusive final-state phase space to enable extraction of all singularities of the real emission matrix elements before integration over any kinematic variable. The exact kinematics of the real emission process are preserved in all regions of phase space. Traditional approaches to extracting singularities from real emission matrix elements, such as phase space slicing and dipole subtraction, require both the determination of counterterms for double real emission…