Hadronic production of top-quark pairs in association with a pair of leptons in the powheg box framework

Journal Article · Fri Jul 01 00:00:00 EDT 2022 · Physical Review D

DOI:https://doi.org/10.1103/PhysRevD.106.014001· OSTI ID:1874614

Ghezzi, Margherita ; Jäger, Barbara ; Lopez Portillo Chavez, Santiago ; Reina, Laura ; Wackeroth, Doreen

We present an implementation of $$t\bar{t}$$ $$\ell$$^⁺$$\ell$$^⁻($$\ell$$ = $$\textit{e}$$, $$\mu$$) 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 $$\textit{a}$$$$^{2}_{s}$$$$\textit{a}$$$$^2$ for the specified final state, as well as the corresponding first-order QCD corrections. Decays of the top quarks have been simulated retaining spin-correlations in all tree-level matrix elements. We consider the case of the Large Hadron Collider at $$\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}$$Z on-shell production with Z → $$\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.

• Research Organization: Florida State Univ., Tallahassee, FL (United States)
• Sponsoring Organization: National Science Foundation (NSF); German Research Foundation (DFG); USDOE Office of Science (SC)
• Grant/Contract Number: SC0010102; PHY-1719690; PHY-2014021; INST 39/963-1 FUGG
• OSTI ID: 1874614
• Alternate ID(s): OSTI ID: 1980135
• Journal Information: Physical Review D, Journal Name: Physical Review D Vol. 106 Journal Issue: 1; ISSN 2470-0010
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English

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Top quark
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