This paper reports detailed calculations that sharpen our understanding of how a common jet-finding method, the Cambridge/Aachen (C/A) algorithm, affects a difficult class of quantum‑chromodynamics (QCD) effects in collisions that produce a vector boson or a Higgs boson plus a jet. The authors compute the pattern of soft radiation that builds the mass of the highest‑momentum jet, working through four orders of perturbation theory, and find that at fixed order the C/A algorithm suppresses large “non-global” radiation effects more effectively than the widely used anti‑kt and kt algorithms. When the authors examine resummed, all‑orders results, C/A behaves similarly to kt. They also confirm that corrections beyond the usual large‑color approximation (finite‑Nc effects) stay at the percent level for realistic values of the observable.

Why focus on the jet mass? When the normalized jet mass is very small (m_j^2/p_t^2 ≪ 1), many radiation effects generate large logarithms that ruin a straightforward perturbative expansion. Some of these, called global logarithms, come from radiation that is uniformly sensitive to the whole event and can be resummed into a Sudakov factor. Non‑global logarithms (NGLs) are harder: they come from correlations between radiation inside and outside the jet and do not exponentiate simply. A separate class, clustering logarithms (CLs), arises when a jet algorithm recombines emissions in a way that spoils certain cancellations. Understanding both NGLs and CLs is important for precision measurements at colliders such as the Large Hadron Collider.

What the researchers did, in plain terms, was to calculate the contributions of NGLs and CLs to the leading jet mass in V/H+jet events up to four loops in fixed‑order perturbation theory. They kept the full dependence on color factors (not just the leading‑color approximation) and on the jet radius R, and they used the eikonal approximation with strong energy ordering of soft gluons to capture all single logarithms. The partonic channels they handled include quark–antiquark, quark–gluon, and gluon–gluon initial states relevant to vector‑boson and Higgs production. The result is a set of semi‑analytical formulae that can be used in phenomenological studies.