The NMSSM lives: with the 750 GeV diphoton excess

TL;DR

This paper presents an NMSSM-based explanation for the 750 GeV diphoton excess observed at the LHC, involving heavy Higgs bosons decaying into collimated photon pairs that mimic a single photon.

Contribution

It introduces a specific NMSSM scenario with a light pseudoscalar that accounts for the excess without exotic matter, and discusses how to distinguish it from other models.

Findings

Reproduces the 750 GeV diphoton excess with heavy Higgs decays

Proposes a production mechanism via initial b quarks

Discusses constraints from low energy experiments

Abstract

We propose an NMSSM scenario that can explain the excess in the diphoton spectrum at 750 GeV recently observed by ATLAS and CMS. We show that in a certain limit with a very light pseudoscalar one can reproduce the experimental results without invoking exotic matter. The 750 GeV excess is produced by two resonant heavy Higgs bosons with masses ~750 GeV, that subsequently decay to two light pseudoscalars. Each of these decays to collimated photon pairs that appear as a single photon in the electromagnetic calorimeter. A mass gap between heavy Higgses mimics a large width of the 750 GeV peak. The production mechanism, containing a strong component via initial b quarks, ameliorates a possible tension with 8 TeV data compared to other production modes. We also discuss other constraints, in particular from low energy experiments. Finally, we discuss possible methods that could distinguish our proposal from other physics models describing the diphoton excess in the Run-II of the LHC.