The leading jet transverse momentum in inclusive jet production and with a loose jet veto

TL;DR

This paper develops a theoretical framework using jet functions to analyze the transverse momentum of the leading jet in inclusive and vetoed jet scenarios, incorporating next-to-leading order calculations and exploring jet radius logarithm resummation.

Contribution

Introduction of leading-jet and subleading-jet functions calculated at NLO for small jet radius, with phenomenological applications to Higgs + 1 jet production.

Findings

The small-R limit describes the NLO result well up to R=0.8.

Leading logarithm resummation alone is insufficient for accurate predictions.

Large corrections at NNLO influence the importance of resumming jet radius logarithms.

Abstract

We study the transverse momentum of the leading jet in the limit where the jet radius is small, $R\ll 1$. We introduce the leading-jet function to calculate this cross section for an inclusive jet sample, and the subleading-jet function when a loose veto on additional jets is imposed, i.e. $p_{T,J} \gtrsim p_T^{\rm veto}$. These jet functions are calculated at next-to-leading order in QCD and the resummation of jet radius logarithms is explored. We present phenomenological results for Higgs + 1 jet production, for both the jet and Higgs transverse momentum distribution. We find that, while the $R \ll 1$ limit of the cross section provides a good description of the full NLO result, even for values as large as $R=0.8$, simply retaining the leading logarithm at this order does not. Indeed, the NLO contribution to the hard function and, to a lesser extent, non-logarithmic corrections to the jet function are sizable and must be included to obtain the correct cross section. In the inclusive cross section we find that the $\alpha_s^2 \ln^2R$ corrections are several precent, while in exclusive cross sections at large $p_{T,J}$ and small $R$ they can reach 20%. However, it is not clear how important the resummation of these logarithms is, given the presence of other large corrections at NNLO.