Abstract
The energy asymmetry in top-antitop-jet production is an observable of the top charge asymmetry designed for the LHC. We perform a realistic analysis in the boosted kinematic regime, including effects of the parton shower, hadronization and expected experimental uncertainties. Our predictions at particle level show that the energy asymmetry in the Standard Model can be measured with a significance of 3σ during Run 3, and with more than 5σ significance at the HL-LHC. Beyond the Standard Model the energy asymmetry is a sensitive probe of new physics with couplings to top quarks. In the framework of the Standard Model Effective Field Theory, we show that the sensitivity of the energy asymmetry to effective four-quark interactions is higher or comparable to other top observables and resolves blind directions in current LHC fits. We suggest to include the energy asymmetry as an important observable in global searches for new physics in the top sector.
Highlights
In the framework of the Standard Model Effective Field Theory, we show that the sensitivity of the energy asymmetry to effective four-quark interactions is higher or comparable to other top observables and resolves blind directions in current LHC fits
The energy asymmetry in ttj production provides a new handle on top quark interactions
In this work we have provided realistic predictions of the energy asymmetry in QCD and in SMEFT for a planned measurement in LHC data
Summary
The energy asymmetry is an LHC observable of the charge asymmetry in top pair production in association with a hard jet, pp → ttj. Due to the partonic boost of the incoming quark, the jet distribution in this process is asymmetric. To reflect this feature, we define an optimized energy asymmetry as [23, 28]. Yttj is the rapidity of the top-antitop-jet system, i.e., the boost of the final state in the laboratory frame This allows us to “guess” the direction of the incoming quark, which tends to be aligned with the boost of the final state. In inclusive top pair production the charge asymmetry can be observed as a rapidity asymmetry [24]. The two observables are sensitive to the interplay between real and virtual QCD effects in different kinematic regimes of top pair production
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