Confronting the 95 GeV excesses within the UN2HDM

TL;DR

This paper investigates whether the observed 95 GeV excesses in various decay channels could be due to one or two actual new scalars within the UN2HDM, a specific Standard Model extension, rather than all being statistical fluctuations.

Contribution

It explores the potential for the UN2HDM to explain selective 95 GeV excesses as real signals, focusing on scenarios where some excesses are fluctuations, which is a novel approach.

Findings

Most excess disappearance scenarios are compatible with type-I UN2HDM.

Type-III UN2HDM can also accommodate these scenarios.

The model can explain why some excesses might not persist in future data.

Abstract

We consider the small excesses around 95 GeV found in several searches for a new scalar in $\gamma \gamma$, $\tau \tau$ and $b \bar b$ final states. Instead of trying to accommodate them all, as is usually done in the literature, in the context of a given Standard Model~(SM) extension, we investigate whether it would be possible that one or two of these excesses correspond to an actual new scalar, while the remaining ones are merely statistical fluctuations. To this end, we use as benchmark model the UN2HDM, a SM extension with one scalar doublet, one scalar singlet, and an extra $\text{U}(1)'$ symmetry, which has been previously studied in the context of multiboson cascade decays. We show that most of the possibilities where the excesses in one or two of these channels disappear in the future can be accommodated by type-I or type-III UN2HDMs.