Promising interpretation of diphoton resonance at 750 GeV

Abstract

Recently, an excess of events in diphoton channel with invariant mass of about 750 GeV has been reported by the ATLAS and CMS Collaborations. Considering it as a tantalizing hint for new physics beyond the Standard Model (SM), we propose a simple extension of the SM with an additional doublet Higgs H and a singlet s. We consider the neutral component H 0 of H as the 750 GeV resonance, and assume that s is lighter than 2.6 GeV. In particular, H 0 can be produced at tree level via qq production, and decay into a pair of s at tree level. And then s can decay into a pair of collimated photons, which cannot be distinguished at the LHC. We show that the diphoton production cross section can be from 3 to 13 fb, the decay width of H 0 can be from 30 to 60 GeV, and all the current experimental constraints including dijet constraint can be satisfied.

Diphotons from diaxions

“…This problem is ameliorated if one instead considers the following process that could mimic a diphoton signal: gg → s → aa → 4γ, where the field a is a very light scalar so that two photons from its decays are highly collimated and can be misidentified as a single photon. 1 In this construction the interaction between s and a can occur at tree, rather 1 The possibility that a pair of photons from a highly boosted particle could be identified as a single photon has previously been studied in [189][190][191][192][193][194][195], and considered in the context of the 750 GeV signal [196][197][198][199][200].…”

A 750 GeV diphoton signal from a very light pseudoscalar in the NMSSM

“…A different approach towards an explanation of the diphoton events is to consider that a single photon in the detector can represent a collimated bunch of photons (typically two of them) which originate from a single very light state, for instance a light pseudoscalar A [5,[30][31][32][33][34][35][36][37]. Then the observed processes correspond to an initial resonance X decaying into a pair A A, where M A must be well below 1 GeV for the resulting photons to be sufficiently collimated (see below).…”

“…However, the extrapolation of signal cross sections from 8 to 13 TeV depends on the assumed production mechanism [5][6][7][8][9]. Assuming the production of a resonance around 750 GeV by gluon fusion (ggF), combined fits to the signal cross sections at 13 TeV are in the range 2-10 fb [5][6][7]9], with slightly better fits and a larger signal cross section assuming a larger width of [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] GeV [5,6,9].…”

Diphoton excess through dark mediators

“…In particular, it is important to ask whether light BSM final states may be confused with the diphoton signal. A general framework for such a scenario has been already discussed in several publications [43][44][45][46]. A heavy resonance X produced by the gluon-gluon or quark-antiquark fusion may decay to a pair of light BSM states Y that have weak instability against subsequent decays to electron-positron pairs or photon pairs.…”