N-Jettiness Subtractions for $gg\to H$ at Subleading Power

TL;DR

This paper analytically and numerically studies subleading power corrections in N-jettiness subtractions for Higgs production via gluon fusion, improving the accuracy and efficiency of NNLO calculations.

Contribution

It provides the first analytical computation of leading power corrections in N-jettiness for $gg o H$, and explores their universality across different channels.

Findings

Analytical expressions for $ au o 0$ power corrections in $gg o H$.

Numerical extraction of power correction coefficients in various channels.

Including power corrections reduces missing contributions, enhancing subtraction method efficiency.

Abstract

$N$-jettiness subtractions provide a general approach for performing fully-differential next-to-next-to-leading order (NNLO) calculations. Since they are based on the physical resolution variable $N$-jettiness, $\mathcal{T}_N$, subleading power corrections in $\tau=\mathcal{T}_N/Q$, with $Q$ a hard interaction scale, can also be systematically computed. We study the structure of power corrections for $0$-jettiness, $\mathcal{T}_0$, for the $gg\to H$ process. Using the soft-collinear effective theory we analytically compute the leading power corrections $\alpha_s \tau \ln\tau$ and $\alpha_s^2 \tau \ln^3\tau$ (finding partial agreement with a previous result in the literature), and perform a detailed numerical study of the power corrections in the $gg$, $gq$, and $q\bar q$ channels. This includes a numerical extraction of the $\alpha_s\tau$ and $\alpha_s^2 \tau \ln^2\tau$ corrections, and a study of the dependence on the $\mathcal{T}_0$ definition. Including such power suppressed logarithms significantly reduces the size of missing power corrections, and hence improves the numerical efficiency of the subtraction method. Having a more detailed understanding of the power corrections for both $q\bar q$ and $gg$ initiated processes also provides insight into their universality, and hence their behavior in more complicated processes where they have not yet been analytically calculated.