Two-loop leading color corrections to heavy-quark pair production in the gluon fusion channel

125

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.

Section: Jhep05(2016)034mentioning

confidence: 99%

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

Czakon

Fiedler

Heymes

et al. 2016

125

“…To present and discuss some features of our results, we recast the obtained coefficients with respect to a basis in color and spin space, in terms the spin density matrix of the top quarks alone. Although our results are obtained with numerical methods, there is also progress in the analytic evaluation of master integrals for this process [18][19][20][21][22].…”

Section: Jhep03(2018)085mentioning

confidence: 99%

Polarized double-virtual amplitudes for heavy-quark pair production

Chen

Czakon

Poncelet

2018

We present the two-loop virtual amplitudes for heavy-quark pair production in light quark-antiquark annihilation and gluon fusion channels, including full spin and color dependence. We use expansions around kinematical limits and numerical integration to obtain results for the involved master integrals. From these, we determine the renormalised infrared finite remainders of the coefficients of amplitude decompositions in terms of color and spin structures. The remainders are given in form of numerical interpolation grids supported by expansions around the production threshold and the high energy limit. Finally, we provide the spin density matrix, which encodes the heavy-quark spin correlations and is sufficient for phenomenological applications. Our results are necessary for the derivation of top-quark pair production cross sections in hadron collisions in the narrow width approximation with next-to-next-to-leading order accuracy in QCD.

“…In terms of the dimensionless variables z ij the phase space reads, We use the delta functions to integrate out z 12 and z 34 , and reparametrise the remaining integration variables as In the soft limit x i → 1, after the trivial integration over χ 4 is performed, our phase space parametrisation completely factorises as, 34 . As a boundary condition for the integrals found in the reduction of A 0 q,Qgg we only needed to compute the soft limit of I [4,7,8] , which reads I (sof t) [4,7,8] In this appendix we collect the seven master integrals found in the IBP reduction of the integrated antenna A 1,lc q,Qg .…”

Section: Jhep12(2015)074mentioning

confidence: 99%

Top quark pair production at NNLO in the quark-antiquark channel

Abelof¹,

Ridder²,

Majer³

2015

We present the derivation of the NNLO two-parton final state contributions to top pair production in the quark-antiquark channel proportionnal to the leading colour factor N 2 c . Together with the three and four-parton NNLO contributions presented in a previous publication, this enables us to complete the phenomenologically most important NNLO corrections to top pair hadro-production in this channel. We derive this two-parton contribution using the massive extension of the NNLO antenna subtraction formalism and implement those corrections in a parton-level event generator providing full kinematical information on all final state particles. In addition, we also derive the heavy quark contributions proportional to N h . Combining the new leading-colour and heavy quark contributions together with the light quark contributions derived previously, we present NNLO differential distributions for LHC and Tevatron. We also compute the differential top quark forward-backward asymmetry at Tevatron and find that our results are in good agreement with the measurements by the D0 collaboration.