Renormalization and scale evolution of the soft-quark soft function

• Published in: The journal of high energy physics Vol. 2020; no. 7; pp. 1 - 37
• Main Authors: Liu, Ze Long, Mecaj, Bianka, Neubert, Matthias, Wang, Xing, Fleming, Sean
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2020; Springer Nature B.V; Springer Berlin; SpringerOpen
• Subjects: Classical and Quantum Gravitation; Decay rate; Effective Field Theories; Elementary Particles; Evolution; Factorization; Gluons; Higgs bosons; High energy physics; Momentum; Operators (mathematics); Perturbative QCD; Physics; Physics and Astronomy; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Quarks; Regular Article - Theoretical Physics; Relativity Theory; Renormalization Group; Resummation; String Theory; Theorems; Renormalization Group; Effective Field Theories; Resummation; Perturbative QCD
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP07(2020)104

A bstract Soft functions defined in terms of matrix elements of soft fields dressed by Wilson lines are central components of factorization theorems for cross sections and decay rates in collider and heavy-quark physics. While in many cases the relevant soft functions are defined in terms of gluon operators, at subleading order in power counting soft functions containing quark fields appear. We present a detailed discussion of the properties of the soft-quark soft function consisting of a quark propagator dressed by two finite-length Wilson lines connecting at one point. This function enters in the factorization theorem for the Higgs-boson decay amplitude of the h → γγ process mediated by light-quark loops. We perform the renormalization of this soft function at one-loop order, present a conjecture for its two-loop anomalous dimension and discuss solutions to its renormalization-group evolution equation in momentum space, in Laplace space and in the “diagonal space”, where the evolution is strictly local in the momentum variable.