Scalar Explanation of Diphoton Excess at LHC

Abstract

Inspired by the diphoton signal excess observed in the latest data of 13 TeV LHC, we consider either a 750 GeV real scalar or pseudo-scalar responsible for this anomaly. We propose a concrete vector-like quark model, in which the vector-like fermion pairs directly couple to this scalar via Yukawa interaction. For this setting the scalar is mainly produced via gluon fusion, then decays at the one-loop level to SM diboson channels $gg,\gamma \gamma ,ZZ,WW$. We show that for the vector-like fermion pairs with exotic electric charges, such model can account for the diphoton excess and is consistent with the data of 8 TeV LHC simultaneously in the context of perturbative analysis.

Comments: v2: 6 pages, 2 figures; v3: 7 pages, typos corrected, discussions about pseudo-scalar explanation added; v4: journal version with text expanded and references added