HEP2026: 42nd Conference on Recent Developments in High Energy Physics and Cosmology [NTUA] Jul 8 – 11, 2026

Probing the Pair Production of Exotic $X_{5/3}$ Quarks in a Vector-Like Doublet Scenario at Muon Collider

Not scheduled

20m

Main Hall (Level 1) (National Technical University of Athens)

Experiments

Speaker

EDA ALICI (ZONGULDAK BULENT ECEVIT UNIVERSTY)

Description

Vector-like quarks are one of the key extensions that address the origin of fermion masses and the hierarchy problem, which is one of the major shortcomings of the Standard Model. In this study, we investigate the pair production process of exotic $X_{5/3}$ quarks within a vector-like doublet scenario at a future $\sqrt{s}=6~\mathrm{TeV}$ muon collider. The signal process of interest is $\mu^+\mu^- \to X_{5/3}\bar{X}_{5/3}$, where the $X_{5/3}$ quark decays primarily via $X_{5/3}\to tW$, leading to a fully leptonic final state containing multiple charged leptons, two $b$-tagged jets, and missing transverse energy.

During the calculations, signal events are generated at the matrix-element level using MadGraph5_aMC@NLO; subsequently, parton showering and hadronization are performed using Pythia8, and detector simulation is carried out using Delphes with the muon-collider detector configuration. In this process, the reference point $g^\ast=0.1$, where the narrow-width approximation holds, is considered, and the $X_{5/3}\to tW$ decay channel is treated as the dominant channel $\left(BR(X_{5/3}\to tW)=1\right)$.

The analysis is performed for two representative mass points, $m_{X_{5/3}}=1.0~\mathrm{TeV}$ and $m_{X_{5/3}}=2.0~\mathrm{TeV}$. For these benchmark points, the signal topology is studied using lepton and jet transverse momentum $(p_T^\ell, p_T^j)$, missing transverse energy $(E_T^{\mathrm{miss}})$, angular separations $(\Delta R)$, and invariant mass distributions $(M_{\mathrm{inv}})$. In this context, the distinctive features of the $4\ell+2b+E_T^{\mathrm{miss}}$ final state under consideration have been identified through these observables, and a cut-based analysis strategy has been developed. Consequently, the study aims to evaluate the potential sensitivity of a high-energy muon collider to exotic $X_{5/3}$ quarks in vector-like doublet models through clean multilepton final states.