Angularity in Higgs boson decays via $\boldsymbol{H\to gg}$ at NNLL$'$ accuracy

TL;DR

This paper improves predictions for angularity distributions in Higgs decays to gluons by resumming logarithms at NNLL' accuracy, determining the gluon-jet function constant, and matching to NLO results, enabling better understanding of nonperturbative effects.

Contribution

The paper introduces a precise determination of the gluon-jet function constant at NNLL' accuracy and enhances the theoretical prediction of angularity distributions in Higgs decays.

Findings

Reasonable agreement with recent thesis value for gluon-jet function constant

Improved accuracy in angularity parameter $a$ for positive values

Enhanced understanding of nonperturbative corrections in Higgs decay distributions

Abstract

We present improved predictions of a class of event-shape distributions called angularity for a contribution from an effective operator $H\to gg$ in Higgs hadronic decay that suffers from large perturbative uncertainties. In the frame of Soft-Collinear Effective Theory, logarithmic terms of the distribution are resummed at NNLL$'$ accuracy, for which 2-loop constant of gluon-jet function for angularity is independently determined by a fit to fixed-order distribution at NLO corresponding to ${\mathcal{O}}(\alpha_s^2)$ relative to the Born rate. Our determination shows reasonable agreement with the value in a thesis recently released. In the fit, we use an asymptotic form with a fractional power conjectured from recoil corrections at one-loop order and it improves the accuracy of determination in positive values of angularity parameter $a$. The resummed distribution is matched to the NLO fixed-order results to make our predictions valid at all angularity values. We also discuss the first moment and subtracted moment of angularity as a function of $a$ that allow to extract information on leading and subleading nonperturbative corrections associated with gluons.