Higgs mixing and diphoton rate enhancement in NMSSM models

TL;DR

This paper explores how Higgs mixing in the NMSSM can enhance diphoton signals while keeping WW and ZZ rates close to the SM, providing insights into Higgs signal deviations and potential new physics effects.

Contribution

It demonstrates that significant diphoton rate enhancement and decay rate reductions are possible in NMSSM without conflicting with existing Higgs measurements.

Findings

Diphoton rate can be enhanced by a factor of 1.5 or more.

Higgs to bb and tautau rates can be reduced by a factor of 0.5.

WW and ZZ signal rates remain close to SM predictions.

Abstract

We study the implications of the LHC Higgs signals on the Higgs mixing in the next-to-minimal supersymmetric standard model (NMSSM). The Higgs couplings can depart from their values in the standard model (SM) due to mixing effects. However the Higgs signal rate in the WW and ZZ channels can remain close to the SM values, as observed at the LHC, even if the SM-like Higgs boson with a mass near 125 GeV has a large singlet component. This allows to get a sizable enhancement in the Higgs to diphoton rate through the charged-higgsino loop contribution, as well as a sizable reduction of the Higgs to bb and tautau rates through the mixing effects, with little deviation in the WW and ZZ signal rates from the SM prediction. We find that an enhancement of diphoton signals by a factor of 1.5 or more, and also a reduction of bb and tautau signals by a factor of 0.5, can be obtained in the region of parameter space consistent with the constraints on the higgsino mass parameter and the singlet coupling to the Higgs doublets, which determine the Higgs mixing.