Differential cross-section measurements of coherent production of singly and doubly resonant top-quark in $WWbb$ events with one lepton at $\sqrt{s}$ = 13 TeV with the ATLAS detector

TL;DR

This paper measures how often certain top-quark related events occur at the LHC, focusing on interference effects between different production modes, and compares these measurements with theoretical models to improve understanding of top-quark physics.

Contribution

It provides the first detailed differential cross-section measurements of $W^{+}W^{-}bar{b}$ events sensitive to interference effects between singly and doubly resonant top-quark production.

Findings

Significant discrepancies observed in interference-sensitive regions.

Results improve understanding of top-quark production mechanisms.

Data offers new constraints for Monte Carlo models.

Abstract

This paper presents differential cross-section measurements of events containing a charged lepton, missing transverse momentum, two $b$-jets, and two light jets, consistent with the $W^{+}W^{-}b\bar{b}$ final state. The analysis is based on 140 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}$ = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider (2015-2018). Differential cross-sections are unfolded at particle level for a range of kinematic observables and in three kinematic regions. Both regions and observables are optimised for sensitivity to the interference between $W^{+}W^{-}b\bar{b}$ produced with singly and doubly resonant top quarks. Results are compared with various theoretical predictions. Significant discrepancies are observed in regions sensitive to the interference between singly and doubly resonant top-quark production. The unfolded results provide new information about the modelling of interference and off-shell effects of the $W^{+}W^{-}b\bar{b}$ final state, improving the understanding of top-quark production mechanisms and providing new inputs for future Monte Carlo generator development.