Search for single production of vector-like B quark decaying to a Higgs boson and bottom quark at the CLIC

Xin Qin,Jie-Fen Shen

doi:10.1016/j.nuclphysb.2021.115388

Abstract

We investigate the prospect of discovering the SU(2) singlet vector-like bottom quark (VLQ-B) in e+e− collisions at future Compact Linear Collider (CLIC) at the 3 TeV stage. As signal process, we focus on single production of the VLQ-B with 4b final state, namely, e+e−→Bb¯→hbb¯ followed by h→bb¯. By carrying out a full detector simulation for the signals and the relevant SM backgrounds, the 2σ exclusion limit and 5σ discovery prospects are, respectively, obtained on the coupling strength κB and the integrated luminosity. For the medium (loose) working point with 70% (90%) b-tagging efficiency, the VLQ-B quark can be excluded in the region of κB∈[0.125,0.24][0.09,0.15] and mB∈[1.3,2.0] TeV, while the discovered region can reach to κB∈[0.19,0.32]([0.14,0.24]). Finally, we also analyze the projected sensitivity in terms of the production cross section times branching fraction at the future 3 TeV CLIC.

Highlights

The vector-like quarks (VLQs) are predicted to solve the gauge hierarchy problem by regulating the Higgs boson mass-squared divergence in many new physics scenarios beyond the Standard Model (SM), such as little Higgs models [1], composite Higgs models [2], and otherX
One can see that for the loose WP with 90% (70%) b-tagging efficiency, the B quark can be excluded in the region of κB ∈ [0.09, 0.15] ([0.125, 0.24]), while the discovered region can reach to κB ∈ [0.14, 0.24] ([0.19, 0.32])
We find that for the loose WP with 90% (70%) b-tagging efficiency, single-B production and decay rates such that σ × BR(B → bh) ∼ 0.1 − 0.15 (0.06 − 0.08) fb could be discovered at the 3 TeV Compact Linear Collider (CLIC) for mass of the VLQ-B (mB) ∈ [1.3, 2.0] TeV, while the cross sections ∼ 0.046 − 0.088 (0.025 − 0.034) fb will be excluded

Summary

Introduction

The vector-like quarks (VLQs) are predicted to solve the gauge hierarchy problem by regulating the Higgs boson mass-squared divergence in many new physics scenarios beyond the Standard Model (SM), such as little Higgs models [1], composite Higgs models [2], and other. The CMS Collaboration presented a search for VLQ-B pair production in the fully hadronic final state using Run 2 data with a total integrated luminosity 137 fb−1 [23], and excluded the B masses up to 1570, 1390, and 1450 GeV for 100% B → bh, 100% B → tZ, and BY doublet cases, respectively. A combination of searches utilizing various final states were performed by the ATLAS Collaboration [24], and excluded values of the B mass up to 1220, 1370, and 1140 GeV for the singlet, the (T , B) doublet and (B, Y ) doublet cases, respectively.

Singlet vector-like bottom quark in the simplified model

Collider simulation and analysis

Findings

Summary