Minijet veto: a tool for the heavy Higgs search at the LHC

TL;DR

The paper addresses the challenge of identifying a very heavy Higgs boson via weak boson scattering at the LHC, where backgrounds from QCD W W and ttbar processes are substantial. It proposes a central minijet veto as a practical proxy for rapidity gaps arising from color-singlet exchange in the signal, and models minijet emission with a truncated shower approximation atop full tree-level calculations. Quantitative results for mH ~ 800 GeV show that, with a minijet veto around pT ~ 20 GeV, backgrounds can be suppressed well below the signal while retaining a sizable event rate (roughly tens of signal events for 100 fb^-1), though the exact gains depend on detector capabilities to lower the veto threshold. The work outlines a feasible strategy to exploit color-flow differences to enhance heavy Higgs searches at the LHC and motivates further experimental and theoretical refinement of minijet activity and gap survival.

Abstract

The distinct color flow of the $qq\to qqH,\; H\to W^+W^-$ process leads to suppressed radiation of soft gluons in the central region, a feature which is not shared by major background processes like $t\bar t$ production or $q\bar q \to W^+W^-$. For the leptonic decay of a heavy Higgs boson, $H\to W^+W^- \to \ell^+ν\ell^-\barν$, it is shown that these backgrounds are typically accompanied by minijet emission in the 20--40 GeV range. A central minijet veto thus constitutes a powerful background rejection tool. It may be regarded as a rapidity gap trigger at the semihard parton level which should work even at high luminosities.