Probing Vector-Like Quarks at a future Muon-Proton Collider

TL;DR

This work evaluates the discovery potential for singly produced vector-like top quarks $T$ at a future muon-proton collider, emphasizing the $T\to Wb$ decay across benchmark $\sqrt{s}$ values. It develops a VLQ single-production framework with couplings $\kappa_W$, $\kappa_Z$, $\kappa_H$ and analyzes cross sections, branching ratios, and decay widths, highlighting the Goldstone Equivalence limit at high mass. Through hadronic and leptonic analyses with cut-based selections, it demonstrates that the $\mu p$ collider at $\sqrt{s}=9.16$ TeV offers significant sensitivity, with hadronic channels yielding higher significance (≈$21.8\sigma$ at $m_T=3$ TeV) than leptonic channels (≈$3.7\sigma$), and an integrated luminosity of $L=3000\,\mathrm{fb}^{-1}$ extending reach to $m_T\approx 3.5$ TeV. The results illustrate the unique advantages of a $\mu p$ machine for probing multi-TeV VLQs in cleaner environments than $pp$ colliders and with higher energy than traditional $ep$ setups, informing future collider program planning.

Abstract

This study investigates the potential for discovering singly produced vector-like top quarks at a muon-proton collider. The analysis reveals that these quarks primarily decay into a W boson accompanied by a bottom quark, which has the largest branching ratio (BR). The research considers the three different center-of-mass energies: 5.29 TeV, 6.48 TeV, and 9.16 TeV. As indicated in our cross-sectional analysis, at 9.16 TeV with a coupling parameter kappa = 0.5, the production probability reaches its peak. However, as the vector-like quark mass exceeds 3 TeV, the production significance diminishes rapidly. For the comparison, the study also performs calculations for proton-proton and electron-proton colliders to highlight the muon-proton collider's effectiveness in probing vector-like quarks. To enhance the detection sensitivity, traditional event selection cuts are applied and optimized. Detailed signal significance calculations suggest that while the hadronic channel yields higher event rates, the leptonic channel offers superior background suppression.

Figures (11)

• Figure 1: (Left)Cross Section comparison at three Colliders. (Right) Cross-section dependence on coupling of VLQ-T at various masses.
• Figure 2: (Left) Branching ratio and (Right) Decay width of vector-like quark into different standard model particles.
• Figure 3: Feynman diagrams background processes decay into leptons
• Figure 4: Transverse momentum of VLQ-T at different masses.
• Figure 5: (Left) The pseudorapidity of all jets from signal and all relevant background processes is shown. (Middle) Jet multiplicity distribution of signal and background processes in their hadronic decay, showing the dominance of background processes. (Right) Transverse momentum distribution of jets for signal and background processes.