On the sensitivity reach of LQ production with preferential couplings to third generation fermions at the LHC

TL;DR

This study explores the potential of the LHC to detect leptoquarks with preferential couplings to third-generation fermions, focusing on their production, decay, and interference effects, to address B-meson decay anomalies.

Contribution

It provides a new analysis of LQ production with third-generation couplings at the LHC, incorporating machine learning and interference effects, extending the discovery reach up to 5 TeV.

Findings

LHC can probe LQ masses up to 5 TeV with high luminosity.

Interference effects significantly impact detection sensitivity.

Machine learning enhances the discovery potential.

Abstract

Leptoquarks (LQs) are hypothetical particles that appear in various extensions of the Standard Model (SM) that can explain observed differences between SM theory predictions and experimental results. The production of these particles has been widely studied at various experiments, most recently at the Large Hadron Collider (LHC), and stringent bounds have been placed on their masses and couplings, assuming the simplest beyond-SM (BSM) hypotheses. However, the limits are significantly weaker for LQ models with family non-universal couplings containing enhanced couplings to third-generation fermions. We present a new study on the production of a LQ at the LHC, with preferential couplings to third-generation fermions, considering proton-proton collisions at $\sqrt{s} = 13$ $\mathrm{TeV}$ and $\sqrt{s} = 13.6$ $\mathrm{TeV}$. Such a hypothesis is well motivated theoretically and it can explain the recent anomalies in the precision measurements of $\mathrm{B}$-meson decay rates, specifically the $R_{D^{(*)}}$ ratios. Under a simplified model where the LQ masses and couplings are free parameters, we focus on cases where the LQ decays to a $\tau$ lepton and a $\mathrm{b}$ quark, and study how the results are affected by different assumptions about chiral currents and interference effects with other BSM processes with the same final states, such as diagrams with a heavy vector boson, $\mathrm{Z}^{'}$. The analysis is performed using machine learning techniques, resulting in an increased discovery reach at the LHC, allowing us to probe new physics phase space which addresses the $\mathrm{B}$-meson anomalies, for $\mathrm{LQ}$ masses up to 5.00 $\mathrm{TeV}$, for the high luminosity LHC scenario.