Jet angular correlation in vector-boson fusion processes at hadron colliders

TL;DR

The paper addresses how jet angular correlations in vector-boson fusion processes can reveal the spin and CP properties of heavy color-singlet states X, including the Higgs boson and RS gravitons, produced with two jets and decaying to vector boson pairs.It develops a comprehensive helicity-amplitude and density-matrix framework for X production (via WBF and GF) and X decay to VV, delivering explicit off-shell current amplitudes and VVX vertices for CP-even/odd Higgs and spin-2 gravitons and linking these to parton splitting in the collinear limit.A key result is that VBF-like kinematic cuts render the VBF amplitudes dominant for X+2 jet production across subprocesses, enabling clean extraction of azimuthal jet correlations arising from quantum interference of intermediate vector-boson helicities; the study also provides detailed production and decay azimuthal distributions for Higgs and gravitons.The findings highlight distinctive, frame- and polarization-dependent angular patterns that encode the spin and CP nature of the heavy states, offering a principled approach to spin determination at the LHC.

Abstract

Higgs boson and massive-graviton productions in association with two jets via vector-boson fusion (VBF) processes and their decays into a vector-boson pair at hadron colliders are studied. They include scalar and tensor boson production processes via weak-boson fusion in quark-quark collisions, gluon fusion in quark-quark, quark-gluon and gluon-gluon collisions, as well as their decays into a pair of weak bosons or virtual gluons which subsequently decay into $\ell\bar\ell$, $q\bar q$ or $gg$. We give the helicity amplitudes explicitly for all the VBF subprocesses, and show that the VBF amplitudes dominate the exact matrix elements not only for the weak-boson fusion processes but also for all the gluon fusion processes when appropriate selection cuts are applied, such as a large rapidity separation between two jets and a slicing cut for the transverse momenta of the jets. We also show that our off-shell vector-boson current amplitudes reduce to the standard quark and gluon splitting amplitudes with appropriate gluon-polarization phases in the collinear limit. Nontrivial azimuthal angle correlations of the jets in the production and in the decay of massive spin-0 and -2 bosons are manifestly expressed as the quantum interference among different helicity states of the intermediate vector-bosons. Those correlations reflect the spin and the CP nature of the Higgs bosons and the massive gravitons.