Diboson anomaly: heavy Higgs resonance and QCD vector-like exotics

TL;DR

This paper proposes that the observed diboson excess at the LHC could be due to a heavy Higgs from a Two Higgs Doublet Model, enhanced by exotic colored fermions, predicting new particles and signals for future detection.

Contribution

It introduces a novel explanation for the diboson anomaly involving a heavy Higgs and exotic colored fermions, expanding the potential new physics scenarios beyond standard models.

Findings

Heavy Higgs production can explain the ATLAS diboson excess.

Colored vector-like fermions significantly enhance gluon fusion cross-section.

Predicted new particles include a CP-odd scalar and colored states below 2 TeV.

Abstract

The ATLAS collaboration (and also CMS) has recently reported an excess over Standard Model expectations for gauge boson pair production in the invariant mass region $1.8-2.2$ TeV. In the light of these results, we argue that such signal might be the first manifestation of the production and further decay of a heavy CP-even Higgs resulting from a type-I Two Higgs Doublet Model. We demonstrate that in the presence of colored vector-like fermions, its gluon fusion production cross-section is strongly enhanced, with the enhancement depending on the color representation of the new fermion states. Our findings show that barring the color triplet case, any QCD "exotic" representation can fit the ATLAS result in fairly large portions of the parameter space. We have found that if the diboson excess is confirmed and this mechanism is indeed responsible for it, then the LHC Run-2 should find: (i) a CP-odd scalar with mass below $\sim 2.3$ TeV, (ii) new colored states with masses below $\sim 2$ TeV, (iii) no statistically significant diboson events in the $W^\pm Z$ channel, (iv) events in the triboson channels $W^\pm W^\mp\,Z$ and $ZZZ$ with invariant mass amounting to the mass of the CP-odd scalar.