Binned top quark spin correlation and polarization observables for the LHC at 13.6 TeV

Abstract

We consider top-antitop quark (tt¯) production at the Large Hadron Collider (LHC) with subsequent decays into dileptonic final states. We use and investigate a set of leptonic angular correlations and distributions with which all the independent coefficient functions of the top-spin-dependent parts of the tt¯ production spin density matrices can be experimentally probed. We compute these observables for the LHC center-of-mass energy 13.6 TeV within the Standard Model at next-to-leading order in the QCD coupling including the mixed QCD weak corrections. We determine also the tt¯ charge asymmetry where we take in addition also the mixed QCD-QED corrections into account. In addition we analyze and compute possible new physics (NP) effects on these observables within effective field theory in terms of a gauge-invariant effective Lagrangian that contains the operators up to mass dimension six that are relevant for hadronic tt¯ production. First, we compute our observables inclusive in phase space. Then, in order to investigate which region in phase space has, for a specific observable, a high NP sensitivity, we determine our observables also in two-dimensional (Mtt¯,cosθt*) bins, where Mtt¯ denotes the tt¯-invariant mass and θt* is the top quark scattering angle in the tt¯ zero-momentum frame. Published by the American Physical Society 2024