Higher-order non-global logarithms from jet calculus

Non-global QCD observables are characterised by a sensitivity to the full angular distribution of soft radiation emitted coherently in hard scattering processes. This complexity poses a challenge to their all-order resummation, that was formulated at the leading-logarithmic order about two decades ago. In this article we present a solution to the long-standing problem of their resummation beyond this order, and carry out the first complete next-to-leading logarithmic calculation for non-global observables. This is achieved by solving numerically the recently derived set of non-linear differential equations which describe the evolution of soft radiation in the planar, large-N-c limit. As a case study we address the calculation of the transverse energy distribution in the interjet rapidity region in e(+)e(-) -> dijet production. The calculation is performed by means of an algorithm that we formulate in the language of jet-calculus generating functionals, which also makes the resummation technique applicable to more general non-global problems, such as those that arise in hadronic collisions. We find that NLL corrections are substantial and their inclusion leads to a significant reduction of the perturbative scale uncertainties for these observables. The computer code used in the calculations is made publicly available.

Automated summary

In this study, we present a solution to the long-standing problem of resummation for non-global QCD observables beyond the leading-logarithmic order. By numerically solving the non-linear differential equations that describe the evolution of soft radiation, we perform the first complete next-to-leading logarithmic calculation for non-global observables in the transverse energy distribution in the interjet rapidity region in e(+)e(-) -> dijet production. We find substantial NLL corrections that significantly reduce the perturbative scale uncertainties for these observables.