NNLO QCD predictions for fully-differential top-quark pair production at the Tevatron

Abstract

We present a comprehensive study of differential distributions for Tevatron top-pair events at the level of stable top quarks. All calculations are performed in NNLO QCD with the help of a fully differential partonic Monte-Carlo and are exact at this order in perturbation theory. We present predictions for all kinematic distributions for which data exists. Particular attention is paid on the top-quark forward-backward asymmetry which we study in detail. We compare the NNLO results with existing approximate NNLO predictions as well as differential distributions computed with different parton distribution sets. Theory errors are significantly smaller than current experimental ones with overall agreement between theory and data.

Dynamical scales for multi-TeV top-pair production at the LHC

“…First, in practical terms, such an agreement allows the use of fixed order results without the need to worry about the numerical impact of soft-gluon resummation. 3 The fact that the fixed order result at a smaller scale is larger than the standard resummed prediction (albeit by a tiny amount) is also consistent with what one might expect about yet uncalculated higher-order effects based purely on the behaviour of the known LO, NLO and NNLO corrections to top-pair production, as well as soft-gluon resummation, where one observes reasonably fast convergence of so-far always positive higher order corrections.…”

“…(1.1) based on restricted independent variation of the factorisation and renormalisation scales has been shown to work very well through NNLO for the total inclusive cross-section [35]. We expect that it will also work well for differential distributions, at least in the bulk low-p T region, and we also extend this variation procedure to the whole kinematic range for all kinematic variables.…”

“…Recent comparison of predictions based on the BLM/PMC and the usual scale setting approaches can be found in ref. [3].…”

Color-singlet production at NNLO in MCFM

“…By partitioning the phase space into appropriate sectors in which each singularity can be made manifest, and then performing a Laurent series expansion to extract the poles. This method has been applied to various processes at the LHC [5,7,34,38].…”

Measurement of top quark polarization in tt¯ lepton+jetsAbazov1, Abbott2, Acharya3 et al. 2017Phys. Rev. D110260View full textAdd to dashboardCite

“…[21,31]. Additionally, we assign an uncertainty in modeling the invariant mass of the tt system (m tt ) based on the difference in m tt distributions in our signal MC and the NNLO predictions [35].…”