Searching for New Physics with $b\bar{b} \ell^+ \ell^-$ Contact Interactions

TL;DR

This paper investigates how contact interactions involving b-quarks and leptons affect high-mass di-lepton events at the LHC, demonstrating improved sensitivity to new physics through optimized b-jet selection strategies.

Contribution

It introduces a novel analysis method focusing on b-jet tagged events to enhance the detection of new physics contact interactions in di-lepton channels at the LHC.

Findings

Single b-jet selection improves sensitivity to new physics.

Expected limits surpass existing LEP bounds by a factor of 1.2-3.1.

Expected LHC limits improve by a factor of 1.3-1.4.

Abstract

We study the impact of contact interactions involving two leptons (electrons or muons) and two $b$-quarks ($b \bar{b} \ell^+ \ell^-$) on the high-mass di-lepton region at the LHC. We consider different selections of $b$-tagged jet multiplicities in the di-lepton final states: inclusive (no selection), 0, 1 and 2 $b$-tagged jets, and show that the single $b$-jet selection significantly improves the sensitivity to New Physics (NP) in the form of the $b \bar{b} \ell^+ \ell^-$ contact term. We obtain a better sensitivity compared to the currently existing searches of NP in the di-lepton inclusive channel. In particular, the expected limits go beyond competitive bounds set by LEP (for electrons) on the scale of NP, $\Lambda$, by a factor of $1.2-3.1$, depending on the chirality structure of the operator. In addition, the expected limits on $\Lambda$, set by using a non-resonant LHC di-lepton inclusive search, are expected to be improved by a factor of $1.3-1.4$ for both electrons and muons.