Eur. Phys. J. C (2025) 85: 379
https://doi.org/10.1140/epjc/s10052-025-14085-1

Regular Article - Theoretical Physics

Probing light scalars and vector-like quarks at the high-luminosity LHC

¹ Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA
² Physics Department, Universidad de los Andes, Bogotá, Colombia

^a ca.florez@uniandes.edu.co

Received: 30 October 2024
Accepted: 15 March 2025
Published online: 2 April 2025

Abstract

A model based on a $U{(1)}_{T_R^3}$ extension of the Standard Model can address the mass hierarchy between generations of fermions, explain thermal dark matter abundance, and the muon $g-2$, $R_{(D)}$, and $R_{(D^{\ast })}$ anomalies. The model contains a light scalar boson ${\varphi }^{\prime }$ and a heavy vector-like quark ${\chi }_{\text{u}}$ that can be probed at CERN’s large hadron collider (LHC). We perform a phenomenology study on the production of ${\varphi }^{\prime }$ and ${\chi }_u$ particles from proton–proton $(\text{pp})$ collisions at the LHC at $\sqrt{s}=13.6$ TeV, primarily through $g-g$ and $t-{\chi }_{\text{u}}$ fusion. We work under a simplified model approach and directly take the ${\chi }_{\text{u}}$ and ${\varphi }^{\prime }$ masses as free parameters. We perform a phenomenological analysis considering ${\chi }_{\text{u}}$ final states to b-quarks, muons, and neutrinos, and ${\varphi }^{\prime }$ decays to ${\mu }^{+}{\mu }^{-}$. A machine learning algorithm is used to maximize the signal sensitivity, considering an integrated luminosity of 3000 ${\text{fb}}^{-1}$. The proposed methodology can be a key mode for discovery over a large mass range, including low masses, traditionally considered difficult due to experimental constraints.