Scrutinizing the 95-100 GeV di-tau excess in the top associated process

TL;DR

This paper investigates a potential light scalar boson causing a di-tau excess at 95-100 GeV, analyzing experimental data to constrain its properties and interpretations, especially in relation to top-associated production and CP nature.

Contribution

It evaluates the experimental sensitivities to a light scalar explaining the di-tau excess and constrains its CP properties using ATLAS and CMS data.

Findings

CP-even scalar interpretation is excluded by ATLAS results.

CP-odd scalar remains a viable explanation.

Top-associated production searches provide strong model-independent limits.

Abstract

Recently, the CMS collaboration has reported a di-tau excess with a local significance of 2.6-3.1$\sigma$ where the invariant mass is $m_{\tau\tau}=$95-100 GeV. This excess can be interpreted as a light scalar boson that couples to the third generation fermions, particularly top and $\tau$. Based on the simplest model that can account for the CMS di-tau excess, we evaluate experimental sensitivities to the additional light resonance, using the results reported by the ATLAS collaboration. We see that a search for the top-quark associated production of the SM Higgs boson that decays into $\tau\bar\tau$ sets a strong model-independent limit. We also find that the CP-even scalar interpretation of the light resonance is excluded by the ATLAS results, while the CP-odd interpretation is not.