Scenarii for interpretations of the LHC diphoton excess: Two Higgs doublets and vector-like quarks and leptons

Abstract

An evidence for a diphoton resonance at a mass of 750 GeV has been observed in the data collected at the LHC run at a center of mass energy of 13 TeV. We explore several interpretations of this signal in terms of Higgs-like resonances in a two-Higgs doublet model and its supersymmetric incarnation, in which the heavier CP-even and CP-odd states present in the model are produced in gluon fusion and decay into two photons through top quark loops. We show that one cannot accommodate the observed signal in the minimal versions of these models and that an additional particle content is necessary. We then consider the possibility that vector-like quarks or leptons strongly enhance the heavy Higgs couplings to photons and eventually gluons, without altering those of the already observed 125 GeV state.

Comments on the diphoton excess: critical reappraisal of effective field theory interpretations

“…The only potentially significant contribution is from the top running in the loop, but even this is always sub-leading. The ratio of S → tt decay width, Γ tt , and the S → γγ rate induced entirely due to top quarks running in the loop, (Γ γγ ) tt , is (Γ γγ ) tt /Γ tt 5×10 −6 [6,49,50]. Using the bound from direct searches for S → tt at 8 TeV, Γ(S → tt)/Γ(S → γγ) 300, shows that the contribution to the S → γγ rate from the top loop is always below O(10 −3 ) and thus negligible.…”

Two Higgs doublets to explain the excesses pp → γγ(750 GeV) and h → τ ± μ ∓

“…The aim of the present paper is to study whether a simple 2HDM could explain both the diphoton excess and the LFV Higgs decay. The LHC excess has been studied in the 2HDM in [4][5][6][7][8][9][10][11][12], and several authors have combined it with other observables, such as the dark matter abundance [64][65][66][67][68][69][70][71][72][73], or B-physics anomalies [95][96][97]. In the 2HDM, candidates for the 750 GeV resonance are the heavier scalar Higgs h 2 and the pseudoscalar A.…”

750 GeV diphotons and supersymmetric grand unification

“…The double resonance scenario was considered in [38], however, it was only tested against the ATLAS 13 TeV data. 3 The sign of the mass splitting is chosen such that the dominant resonance is heavier.…”

“…An obvious candidate for the diphoton excess is a singlet which couples to gluons (photons) via new vector-like colored (charged) particles running in the loop. Simple bottom-up constructions of this type were presented in [3][4][5][6][7]. Vector-like 'exotics' are very common in string model constructions such as D-brane theories [8] or heterotic string compactifications [9].…”