89 research outputs found
Two-Loop Master Integrals for the Planar QCD Massive Corrections to Di-photon and Di-jet Hadro-production
We present the analytic calculation of the Master Integrals necessary to
compute the planar massive QCD corrections to Di-photon (and Di-jet) production
at hadron colliders. The masters are evaluated by means of the differential
equations method and expressed in terms of multiple polylogarithms and one- or
two-fold integrals of polylogarithms and irrational functions, up to
transcendentality four.Comment: 20 pages, ancillary file
Master Integrals for double real radiation emission in heavy-to-light quark decay
We evaluate analytically the master integrals for double real radiation
emission in the b --> u W* decay, where b and u are a massive and massless
quark, respectively, while W* is an off-shell charged weak boson. Since the W
boson can subsequently decay in a lepton anti-neutrino pair, the results of the
present paper constitute a further step toward a fully analytic computation of
differential distributions for the semileptonic decay of a b quark at NNLO in
QCD. The latter partonic process plays a crucial role in the study of inclusive
semileptonic charmless decays of B mesons. Our results are expressed in terms
of multiple polylogarithms of maximum weight four.Comment: 21 pages, 6 figures, 2 table
Two-Loop Master Integrals for the mixed EW-QCD virtual corrections to Drell-Yan scattering
We present the calculation of the master integrals needed for the two-loop
QCDxEW corrections to and for massless external particles. We treat W and Z bosons
as degenerate in mass. We identify three types of diagrams, according to the
presence of massive internal lines: the no-mass type, the one-mass type, and
the two-mass type, where all massive propagators, when occurring, contain the
same mass value. We find a basis of 49 master integrals and evaluate them with
the method of the differential equations. The Magnus exponential is employed to
choose a set of master integrals that obeys a canonical system of differential
equations. Boundary conditions are found either by matching the solutions onto
simpler integrals in special kinematic configurations, or by requiring the
regularity of the solution at pseudo-thresholds. The canonical master integrals
are finally given as Taylor series around d=4 space-time dimensions, up to
order four, with coefficients given in terms of iterated integrals,
respectively up to weight four.Comment: 1+45 pages, 6 figures, 1 table, 5 ancillary file
The subtraction method for top quark production at hadron colliders
We consider QCD radiative corrections to top-quark pair production at hadron
colliders. We use the subtraction formalism to perform a
fully-differential computation for this process. Our calculation is accurate up
to the next-to-leading order in QCD perturbation theory and it includes all the
flavour off-diagonal partonic channels at the next-to-next-to-leading order. We
present a comparison of our numerical results with those obtained with the
publicly available numerical programs MCFM and Top++.Comment: Few references and comments added, expanded discussion on the qt
subtraction method, result unchanged, version published in EPJ
Planar master integrals for the two-loop light-fermion electroweak corrections to Higgs plus jet production
We present the analytic calculation of the planar master integrals which
contribute to compute the two-loop light-fermion electroweak corrections to the
production of a Higgs boson in association with a jet in gluon-gluon fusion.
The complete dependence on the electroweak-boson mass is retained. The master
integrals are evaluated by means of the differential equations method and the
analytic results are expressed in terms of multiple polylogarithms up to weight
four.Comment: 21 pages, ancillary file
Master Integrals for the two-loop, non-planar QCD corrections to top-quark pair production in the quark-annihilation channel
We present the analytic calculation of the Master Integrals for the two-loop,
non-planar topologies that enter the calculation of the amplitude for top-quark
pair hadroproduction in the quark-annihilation channel. Using the method of
differential equations, we expand the integrals in powers of the dimensional
regulator and determine the expansion coefficients in terms of
generalized harmonic polylogarithms of two dimensionless variables through to
weight four.Comment: 28 pages, 2 figures, ancillary files include
Full top-quark mass dependence in diphoton production at NNLO in QCD
In this paper we consider the diphoton production in hadronic collisions at
the next-to-next-to-leading order (NNLO) in perturbative QCD, taking into
account for the first time the full top quark mass dependence up to two loops
(full NNLO). We show selected numerical distributions, highlighting the
kinematic regions where the massive corrections are more significant. We make
use of the recently computed two-loop massive amplitudes for diphoton
production in the quark annihilation channel. The remaining massive
contributions at NNLO are also considered, and we comment on the weight of the
different types of contributions to the full and complete result.Comment: 14 pages and 5 figure
NNLO QCDEW corrections to Z production in the channel
We present the first results for the corrections
to the total partonic cross section of the process , with the
complete set of contributions, that include photonic and massive weak gauge
boson effects. The results are relevant for the precise determination of the
hadronic boson production cross section. Virtual and real corrections are
calculated analytically using the reduction to the master integrals and their
evaluation through differential equations. Real corrections are dealt with
using the reverse-unitarity method. They require the evaluation of a new set of
two-loop master integrals, with up to three internal massive lines. In
particular, three of them are expressed in terms of elliptic integrals. We
verify the absence, at this perturbative order, of initial state mass
singularities proportional to a weak massive virtual correction to the
quark-gluon splitting.Comment: 6 pages, 1 figur
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