Testing the $R_{D^{(*)}}$ Anomaly at the LHeC

TL;DR

This paper investigates the potential of the LHeC collider to detect the $R_2$ leptoquark, which could explain B-Physics anomalies, by analyzing its resonance in the $b\tau$ final state and assessing discovery prospects.

Contribution

It provides a detailed analysis of the LHeC's sensitivity to the $R_2$ leptoquark, highlighting its discovery potential even for small couplings, and constrains its mass range based on current limits.

Findings

LHeC can discover $R_2$ leptoquark with small couplings.

Mass of $R_2$ constrained to 800-1000 GeV by current limits.

High discovery potential at LHeC for $R_2$ resonance.

Abstract

B-Physics anomalies have recently raised renewed interest in leptoquarks (LQ), predicted in several theoretical frameworks. Under simplifying but conservative assumptions, we show that the current limits from LHC searches together with the requirement to explain the observed value for $R_{D^{(*)}}$ constrain the $R_2$ leptoquark mass to be in the range of $800 \leq m_{R_2} \leq 1000$ GeV. We study the search for $R_2$ at the LHeC via its resonance in the $b\tau$ final state by performing a cut-and-count analysis of the signal and the dominant Standard Model backgrounds. We find that the LHeC has an excellent discovery potential for $R_2$ even for couplings to the first generation as small as ${\cal O}(10^{-2})$.