Collinear limits beyond the leading order from the scattering equations

108

162

Soft and collinear radiation is responsible for large corrections to many hadronic cross sections, near thresholds for the production of heavy final states. There is much interest in extending our understanding of this radiation to next-to-leading power (NLP) in the threshold expansion. In this paper, we generalise a previously proposed all-order NLP factorisation formula to include non-abelian corrections. We define a nonabelian radiative jet function, organising collinear enhancements at NLP, and compute it for quark jets at one loop. We discuss in detail the issue of double counting between soft and collinear regions. Finally, we verify our prescription by reproducing all NLP logarithms in Drell-Yan production up to NNLO, including those associated with double real emission. Our results constitute an important step in the development of a fully general resummation formalism for NLP threshold effects.

Section: Jhep12(2016)121mentioning

confidence: 99%

Non-abelian factorisation for next-to-leading-power threshold logarithms

Bonocore

Laenen

Magnea

et al. 2016

108

162

“…It would be interesting to understand in more detail the universality of collinear splittings at subleading power, as well as collinear factorization properties. For some recent work in this direction from a different perspective, see [68,69]. The behavior of these Wilson coefficients is also quite interesting.…”

Section: Jhep07(2017)067mentioning

confidence: 99%

A subleading operator basis and matching for gg → H

Moult

Stewart

Vita

2017

107

The Soft Collinear Effective Theory (SCET) is a powerful framework for studying factorization of amplitudes and cross sections in QCD. While factorization at leading power has been well studied, much less is known at subleading powers in the λ 1 expansion. In SCET subleading soft and collinear corrections to a hard scattering process are described by power suppressed operators, which must be fixed case by case, and by well established power suppressed Lagrangians, which correct the leading power dynamics of soft and collinear radiation. Here we present a complete basis of power suppressed operators for gg → H, classifying all operators which contribute to the cross section at O(λ 2 ), and showing how helicity selection rules significantly simplify the construction of the operator basis. We perform matching calculations to determine the tree level Wilson coefficients of our operators. These results are useful for studies of power corrections in both resummed and fixed order perturbation theory, and for understanding the factorization properties of gauge theory amplitudes and cross sections at subleading power. As one example, our basis of operators can be used to analytically compute power corrections for N -jettiness subtractions for gg induced color singlet production at the LHC.

“…The study of such contributions for arbitrary processes and at higher orders in perturbation theory deserves further investigation (although see Ref. [55] for a discussion in a more formal context).…”

Section: Nlp Contributions In Dis At Nlomentioning

confidence: 99%

“…Secondly, the great interest in next-to-soft theorems has yet to be supplemented with a systematic investigation of subleading collinear behaviour (although Ref. [55] is a notable exception), and we hope that our results provide a useful springboard for further work.…”

Section: Introductionmentioning

confidence: 98%

Next-to-leading power threshold effects for inclusive and exclusive processes with final state jets

Beekveld

Beenakker

Laenen

et al. 2020

It is well known that cross-sections in perturbative QCD receive large corrections from soft and collinear radiation, whose properties must be resummed to all orders in the coupling. Whether or not the universal properties of this radiation can be extended to next-to-leading power (NLP) in the threshold expansion has been the subject of much recent study. In this paper, we consider two types of NLP effects: the interplay of next-to-soft and collinear radiation in processes with final state jets and the NLP contributions stemming from soft quarks. We derive an NLP amplitude for soft gluons and quarks, valid for an arbitrary number of coloured or colourless massless final state particles. We show explicitly that this framework can be used to correctly obtain the dominant NLP effects in three different types of processes at next-to-leading order: deep-inelastic scattering, hadroproduction via electron-positron annihilation and prompt photon production. Our results provide an important ingredient for developing a universal resummation formalism for NLP effects.