The resummation of inter-jet energy flow for gaps-between-jets processes at HERA

TL;DR

The paper tackles gaps-between-jets energy flow in photoproduction at HERA by performing LL resummation of interjet soft radiation using Collins–Soper–Sterman factorisation in color space, including global primary logs and an approximate treatment of non-global logs in the large $N_c$ limit. It derives soft anomalous-dimension matrices for kt-defined gaps, implements refactorisation to separate soft and hard dynamics, and computes energy-flow observables that are directly comparable to H1/ZEUS data. The results show good agreement in the shape and normalization of gap fractions within quantified perturbative uncertainties, highlighting the impact of gap-area differences between kt- and cone-based definitions and the importance of NG effects. The work provides a framework for precision predictions of non-global observables in jet-gap processes and outlines clear paths to improve NG treatments and include non-perturbative power corrections.

Abstract

We calculate resummed perturbative predictions for gaps-between-jets processes and compare to HERA data. Our calculation of this non-global observable needs to include the effects of primary gluon emission (global logarithms) and secondary gluon emission (non-global logarithms) to be correct at the leading logarithm (LL) level. We include primary emission by calculating anomalous dimension matrices for the geometry of the specific event definitions and estimate the effect of non-global logarithms in the large $N_c$ limit. The resulting predictions for energy flow observables are consistent with experimental data.