$SU(2{)}_L$ triplet scalar as the origin of the 95 GeV excess?

Abstract

We explore the possibility that an $SU(2{)}_L$ triplet scalar with hypercharge $Y=0$ is the origin of the $95$GeV diphoton excess. For a small mixing angle with the Standard Model Higgs, its neutral component has naturally a sizable branching ratio to $\gamma \gamma$ such that its Drell-Yan production via $pp\to W^{\ast }\to H{H}^{\pm }$ is sufficient to obtain the desired signal strength, where $H^{\pm }$ is the charged Higgs component of the triplet. The predictions of this setup are: 1) The $\gamma \gamma$ signal has a $p_T$ spectrum different from gluon fusion but similar to associated production. 2) Photons are produced in association with tau leptons and jets, but generally do not fall into the vector-boson fusion category. 3) The existence of a charged Higgs with $m_{H^{\pm }}\approx (95\pm 5)$GeV leading to $\sigma (pp\to \tau \tau \nu \nu )\approx 0.4$pb, which is of the same level as the current limit and can be discovered with Run 3 data. 4) A positive definite shift in the $W$ mass as suggested by the current global electroweak fit.

Comments: 12 pages, 5 figures, version accepted for publication in PRD Letter