Hadronic production of top-quark pairs in association with a pair of leptons in the POWHEG BOX framework

Abstract

We present an implementation of $t\bar{t}{\ell }^{+}{\ell }^{-}$ ($\ell =e,\mu$) hadronic production at next-to-leading order in QCD matched to parton-shower event generators in the POWHEG BOX framework. The program we developed includes all leading-order contributions of order ${\alpha }_s^2{\alpha }^2$ for the specified final state, as well as the corresponding first-order QCD corrections. Decays of the top quarks have been simulated retaining spin-correlations in all tree-level matrix elements. We consider the case of the Large Hadron Collider at $\sqrt{s}=13$ TeV and compare results for $t\bar{t}{\ell }^{+}{\ell }^{-}$ production in the fiducial volume where the invariant mass of the lepton pairs is centered around the $Z$-boson mass to corresponding predictions for $t\bar{t}Z$ on-shell production with $Z\to {\ell }^{+}{\ell }^{-}$. We find that off-shell effects in $t\bar{t}{\ell }^{+}{\ell }^{-}$ are in general small at the level of the total cross section, but can decrease the tail of the leptons' transverse momentum distributions by 10-20% and, in these regions, they are visible beyond the scale uncertainty due to renormalization and factorization scale variation. Moreover, we find that accounting for top-quark decays in the narrow-width approximation with tree-level spin correlations also gives origin to 10-20% effects in specific regions of the kinematic distributions of the $t\bar{t}{\ell }^{+}{\ell }^{-}$ decayed final state.

22 pages, 13 figures

References in corpus (25)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• An Introduction to PYTHIA 8.2
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• LHAPDF6: parton density access in the LHC precision era
• Tuning PYTHIA 8.1: the Monash 2013 Tune
• A standard format for Les Houches Event Files
• Higgs boson production in association with top quarks in the POWHEG BOX
• t tbar W and t tbar Z Hadroproduction at NLO accuracy in QCD with Parton Shower and Hadronization effects
• Next-to-leading order QCD corrections to t-tbar-Z production at the LHC
• Measurement of the $t\bar{t}Z$ and $t\bar{t}W$ cross sections in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Associated production of a top quark pair with a heavy electroweak gauge boson at NLO+NNLL accuracy
• Top-quark charge asymmetry and polarization in $t\bar{t}{W}^{\pm }$ production at the LHC
• On improving NLO merging for $t\bar{t}W$ production
• Measurement of the $t\bar{t}Z$ and $t\bar{t}W$ production cross sections in multilepton final states using 3.2 fb${}^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector
• Anatomy of inclusive $t\overline{t}W$ production at hadron colliders
• Top-quark pair production in association with a $W^{\pm }$ gauge boson in the POWHEG-BOX
• The simplest of them all: $t\bar{t}{W}^{\pm }$ at NLO accuracy in QCD
• Measurements of the inclusive and differential production cross sections of a top-quark-antiquark pair in association with a $Z$ boson at $\sqrt{s}=13$ TeV with the ATLAS detector
• Renormalization group improved predictions for $t\bar{t}{W}^{\pm }$ production at hadron colliders
• Associated production of a top pair and a W boson at next-to-next-to-leading logarithmic accuracy
• Combined NLO EW and QCD corrections to off-shell $\text{t}\overline{\text{t}}\text{W}$ production at the LHC
• Modeling uncertainties of $t\bar{t}{W}^{\pm }$ multilepton signatures
• NLO QCD corrections to off-shell $\text{t}\bar{\text{t}}{\text{W}}^{+}$ production at the LHC
• Updates to the One-loop Provider NLOX
• The impact of top-quark modelling on the exclusion limits in $\mathbf{t}\bar{\mathbf{t}}+\text{DM}$ searches at the LHC

Cited by in corpus (5)

• Event Generators for High-Energy Physics Experiments
• Les Houches 2021: Physics at TeV Colliders: Report on the Standard Model Precision Wishlist
• NLO QCD corrections to full off-shell production of $t\bar{t}Z$ including leptonic decays
• On two-body and three-body spin correlations in leptonic $t\bar{t}Z$ production and anomalous couplings at the LHC
• Les Houches 2023 -- Physics at TeV Colliders: Report on the Standard Model Precision Wishlist