750 GeV Resonance in the Gauged $U(1)'$-Extended MSSM

TL;DR

This paper explores how an extended MSSM with an extra U(1)' gauge symmetry can explain the 750 GeV di-photon resonance observed at the LHC, proposing multiple mechanisms and benchmark scenarios involving vector-like quarks and scalar production.

Contribution

It introduces novel MSSM extensions with U(1)' symmetry to account for the 750 GeV resonance, detailing mechanisms and benchmark scenarios for its production and decay.

Findings

The 750 GeV resonance can be explained as a singlet-like scalar or pseudoscalar.

Multiple production mechanisms are viable, including vector-like quark mediation and associated production.

Some Z'-mediated production channels may be constrained by existing LHC searches.

Abstract

Recently the ATLAS and CMS collaborations at the LHC announced their observation of a potential 750 GeV di-photon resonance, after analyzing the $\sqrt{s}=13$ TeV LHC data. This observation has significant implications for low-energy supersymmetry. Beyond the MSSM and the NMSSM, we study the MSSM-extensions with an extra $U(1)'$ gauge symmetry. The anomaly cancellation and the spontaneous breaking of the non-decoupled $U(1)'$ generically require introducing vector-like supermultiplets (both colored and color-neutral ones) and singlet supermultiplets, respectively. We illustrate that the potential 750 GeV resonance ($Y$) can be accommodated in various mechanisms, as a singlet-like scalar or pseudoscalar. Three benchmark scenarios are presented: (1) vector-like quarks (VLQ) mediated $pp \to Y \to \gamma \gamma$; (2) scalar VLQ mediated $pp \to Y \to \gamma \gamma$; (3) heavy scalar (pseudo-scalar) $H/A$ associated production $pp \to H^*/A^* \to Y H/h$. Additionally, we notice that the $Z'$-mediated vector boson fusion production and $Z'$-associated production $pp \to Y qq'$, if yielding a signal rate of the observed level, might have been excluded by the searches for $Z'$ via Drell-Yan process at the LHC.