Impact of hidden heavy Higgs channels of VLB-Quarks below 1 TeV in 2HDM

TL;DR

This paper studies how new decay channels involving heavy Higgs bosons affect the mass constraints of vector-like bottom quarks in the 2HDM, showing that these channels weaken existing bounds significantly.

Contribution

It introduces and analyzes the impact of BSM decay channels of VLB quarks in 2HDM-II, revealing their effect on current mass limits and decay patterns.

Findings

BSM decay channels weaken VLB mass constraints.

Mass limits drop from ~1.5 TeV to ~1.34 TeV in the alignment limit.

Decay channels $B o Hb$ and $B o Ab$ can dominate with nearly 100 ext{ }branching ratio.

Abstract

We investigate the phenomenological impact of incorporating vector-like bottom (VLB) quarks into the Type-II Two-Higgs-Doublet Model (2HDM-II). This framework introduces novel beyond-Standard-Model (BSM) decay channels $B \to Hb$, $B \to Ab$, and $B \to H^-t$, which are typically ignored by LHC pair-production searches focused on Standard Model (SM) final states ($B \to Zb$, $B \to hb$, $B \to Wt$). Our analysis reveals that these BSM pathways significantly weaken current VLB mass constraints. In the 2HDM-II alignment limit, the mass limit for a singlet $B$ shifts from approximately 1.5 TeV down to 1.34 TeV. For $(T, B)$ and $(B, Y)$ doublet configurations, the mass limits relax further to approximately 0.98 TeV, driven by the dominance of $B \to Hb$ and $B \to Ab$ decays, which can reach combined branching ratios of nearly 100\%.