Leading-logarithmic threshold resummation of Higgs production in gluon fusion at next-to-leading power

There has been recent interest in understanding the all loop structure of the subleading power soft and collinear limits, with the goal of achieving a systematic resummation of subleading power infrared logarithms. Most of this work has focused on subleading power corrections to soft gluon emission, whose form is strongly constrained by symmetries. In this paper we initiate a study of the all loop structure of soft fermion emission. In N = 1 QCD we perform an operator based factorization and resummation of the associated infrared logarithms using the formalism introduced in [1], and prove that they exponentiate into a Sudakov due to their relation to soft gluon emission. We verify this result through explicit calculation to O(α 3 s). We show that in QCD, this simple Sudakov exponentiation is violated by endpoint contributions proportional to (C A − C F) n which contribute at leading logarithmic order. Combining our N = 1 result and our calculation of the endpoint contributions to O(α 3 s), we conjecture a result for the soft quark Sudakov in QCD, a new all orders function first appearing at subleading power, and give evidence for its universality. Our result, which is expressed in terms of combinations of cusp anomalous dimensions in different color representations, takes an intriguingly simple form and also exhibits interesting similarities to results for large-x logarithms in the off diagonal splitting functions.

Section: Introductionmentioning

confidence: 99%

The soft quark Sudakov

Moult

Stewart

Vita

et al. 2020

“…To improve the numerical performance, these power corrections can be included systematically by computing them in an expansion in the resolution variable about the soft and collinear limits. Recently, there has been significant interest and progress in understanding collider cross sections at subleading power [52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69]. In particular, for inclusive Higgs and Drell-Yan production the leading-logarithmic (LL) corrections at NNLO at next-to-leading power (NLP) are known for T 0 [70][71][72].…”

Section: Introductionmentioning

confidence: 99%

Impact of isolation and fiducial cuts on qT and N-jettiness subtractions

Ebert

Tackmann

2020

Kinematic selection cuts and isolation requirements are a necessity in experimental measurements for identifying prompt leptons and photons that originate from the hard-interaction process of interest. We analyze how such cuts affect the application of the q T and N-jettiness subtraction methods for fixed-order calculations. We consider both fixed-cone and smooth-cone isolation methods. We find that kinematic selection and isolation cuts both induce parametrically enhanced power corrections with considerably slower convergence compared to the standard power corrections that are already present in inclusive cross sections without additional cuts. Using analytic arguments at next-to-leading order we derive their general scaling behavior as a function of the subtraction cutoff. We also study their numerical impact for the case of gluon-fusion Higgs production in the H → γγ decay mode and for pp → γγ direct diphoton production. We find that the relative enhancement of the additional cut-induced power corrections tends to be more severe for q T , where it can reach an order of magnitude or more, depending on the choice of parameters and subtraction cutoffs. We discuss how all such cuts can be incorporated without causing additional power corrections by implementing the subtractions differentially rather than through a global slicing method. We also highlight the close relation of this formulation of the subtractions to the projection-to-Born method.

“…for the result including quarks in QCD was presented in [57]. Subleading power infrared logarithms have also been resummed for color singlet production at kinematic threshold, when only soft real radiation is present [42,51,55].…”

Section: Introductionmentioning

confidence: 99%

Subleading power resummation of rapidity logarithms: the energy-energy correlator in $$ \mathcal{N} $$ = 4 SYM

Moult

Vita

Yan

2020

We derive and solve renormalization group equations that allow for the resummation of subleading power rapidity logarithms. Our equations involve operator mixing into a new class of operators, which we term the "rapidity identity operators", that will generically appear at subleading power in problems involving both rapidity and virtuality scales. To illustrate our formalism, we analytically solve these equations to resum the power suppressed logarithms appearing in the back-to-back (double light cone) limit of the Energy-Energy Correlator (EEC) in N = 4 super-Yang-Mills. These logarithms can also be extracted to O(α 3 s) from a recent perturbative calculation, and we find perfect agreement to this order. Instead of the standard Sudakov exponential, our resummed result for the subleading power logarithms is expressed in terms of Dawson's integral, with an argument related to the cusp anomalous dimension. We call this functional form "Dawson's Sudakov". Our formalism is widely applicable for the resummation of subleading power rapidity logarithms in other more phenomenologically relevant observables, such as the EEC in QCD, the p T spectrum for color singlet boson production at hadron colliders, and the resummation of power suppressed logarithms in the Regge limit.