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.
Highlights
The ATLAS [1] and CMS [2] experiments at the Large Hadron Collider (LHC) have both reported an excess in the diphoton channel at an invariant mass of about 750 GeV corresponding to a local significance of 3.6 σ (2.0 σ ) and 2.6 σ (1.2 σ ), respectively
One should consider the low-energy constraints more carefully, as charged-Higgs contributions to B → Xsγ can no longer be balanced by the SUSY loops and the anomalous magnetic moment of the muon would suffer from the negative contributions driven by the loop involving the muon and the light pseudoscalar if the 2HDM is of Type II
We have proposed an Next-to-Minimal Supersymmetric Standard Model (NMSSM) scenario that can explain the excess in the diphoton spectrum at 750 GeV recently observed by ATLAS and CMS
Summary
The ATLAS [1] and CMS [2] experiments at the Large Hadron Collider (LHC) have both reported an excess in the diphoton channel at an invariant mass of about 750 GeV corresponding to a local (global) significance of 3.6 σ (2.0 σ ) and 2.6 σ (1.2 σ ), respectively. Strict constraints exist on decays of heavy resonances into electroweak gauge bosons and light Standard Model (SM) fermions and the resonance should decay into final states which evade all current experimental searches, implying e.g. a large invisible decay rate or decays to quarks and gluons. Another way out (which we consider in this paper) would be the presence of two overlapping resonances with narrow widths which allow one to explain the large width within the current experimental accuracy [8]. We will conclude with a brief summary in the last section
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