Branching Ratios of $H_{1,2,3} \rightarrow \mu^{+}\mu^{-}$ in the Broken-Phase N2HDM

TL;DR

This paper calculates the branching ratios of three Higgs bosons decaying into muon pairs within the N2HDM, incorporating radiative corrections and analyzing deviations from the Standard Model to explore new physics signals.

Contribution

It provides the first detailed analysis of $H_{i} ightarrow bcb5$ branching ratios in the broken-phase N2HDM, including one-loop corrections and parameter space constraints.

Findings

Identifies viable N2HDM parameter regions consistent with ATLAS data.

Shows potential for enhanced dimuon signals in extended Higgs sectors.

Demonstrates the importance of precision measurements in probing new physics.

Abstract

Recent evidence from the ATLAS Collaboration for the rare decay $H \rightarrow \mu^{+}\mu^{-}$ provides a unique window into the Higgs boson's coupling to second-generation fermions. In this work, we investigate how this signal can probe physics beyond the Standard Model by computing the branching ratios $B(H_{i} \rightarrow \mu^{+}\mu^{-})$ for the three CP-even Higgs bosons $H_{1,2,3}$ in the broken-phase Next-to-Two-Higgs-Doublet Model (N2HDM). We incorporate one-loop radiative corrections and analyze deviations from the Standard Model prediction due to modified Yukawa couplings, scalar mixing, and singlet--doublet interactions. By confronting our results with the ATLAS signal strength $\mu = 1.4 \pm 0.4$, we identify viable regions of the N2HDM parameter space, characterized by tan$\beta$, the singlet vacuum expectation value, and scalar masses, and assess the model's capacity to explain potential enhancements in the dimuon channel. Our study demonstrates that precision measurements of $H \rightarrow \mu^{+}\mu^{-}$ serve as a powerful tool to test extended Higgs sectors and uncover new physics at current and future colliders.