Validity of the CMSSM interpretation of the diphoton excess

TL;DR

This paper critically reexamines the CMSSM explanation for the 750 GeV diphoton excess, showing that key parameter regions are ruled out by vacuum stability and decay constraints, making the scenario unlikely.

Contribution

It extends previous analyses by including vacuum stability and decay constraints, demonstrating these exclude the parameter space needed for the diphoton excess explanation.

Findings

Parameter space with light stop and Higgs mass is ruled out.

Bound state effects are negligible in the relevant regions.

Diphoton production cross section is too small to explain the excess.

Abstract

It has been proposed that the observed diphoton excess at 750 GeV could be explained within the constrained minimal supersymmetric standard model via resonantly produced stop bound states. We reanalyze this scenario critically and extend previous work to include the constraints from the stability of the electroweak vacuum and from the decays of the stoponium into a pair of Higgs bosons. It is shown that the interesting regions of parameter space with a light stop and Higgs of the desired mass are ruled out by these constraints. This conclusion is not affected by the presence of the bound states because the binding energy is usually very small in the regions of parameter space which can explain the Higgs mass. Thus, this also leads to strong constraints on the diphoton production cross section which is in general too small.