52 research outputs found
Higgs production in bottom-quark fusion to third order in the strong coupling
We present the inclusive cross section at next-to-next-to-next-to-leading
order (NLO) in perturbative QCD for the production of a Higgs boson via
bottom-quark fusion. We employ the five-flavour scheme, treating the bottom
quark as a massless parton while retaining a non-vanishing Yukawa coupling to
the Higgs boson. We find that the dependence of the hadronic cross section on
the renormalisation and factorisation scales is substantially reduced. For
judicious choices of the scales the perturbative expansion of the cross section
shows a convergent behaviour. We present results for the NLO cross section
at various collider energies. In comparison to the cross section obtained from
the Santander-matching of the four and five-flavour schemes we predict a
slightly higher cross section, though the two predictions are consistent within
theoretical uncertainties.Comment: 3 pretty plots with pretty colours. Published versio
Charged Current Drell-Yan Production at N3LO
We present the production cross section for a lepton-neutrino pair at the
Large Hadron Collider computed at next-to-next-to-next-to leading order (N3LO)
in QCD perturbation theory. We compute the partonic coefficient functions of a
virtual boson at this order. We then use these analytic functions to
study the progression of the perturbative series in different observables. In
particular, we investigate the impact of the newly obtained corrections on the
inclusive production cross section of bosons, as well as on the
ratios of the production cross sections for , and/or a virtual
photon. Finally, we present N3LO predictions for the charge asymmetry at the
LHC.Comment: 22 pages, 11 figures. v2: Fixed mistake in figure
The Drell-Yan cross section to third order in the strong coupling constant
We present phenomenological results for the inclusive cross section for the
production of a lepton-pair via virtual photon exchange at
next-to-next-to-next-to-leading order (NLO) in perturbative QCD. In line
with the case of Higgs production, we find that the hadronic cross section
receives corrections at the percent level, and the residual dependence on the
perturbative scales is reduced. However, unlike in the Higgs case, we observe
that the uncertainty band derived from scale variation is no longer contained
in the band of the previous order.Comment: Published versio
The Four-Loop Rapidity Anomalous Dimension and Event Shapes to Fourth Logarithmic Order
We obtain the quark and gluon rapidity anomalous dimension to fourth order in
QCD. We calculate the NLO rapidity anomalous dimensions to higher order in
the dimensional regulator and make use of the soft/rapidity anomalous dimension
correspondence in conjunction with the recent determination of the NLO
threshold anomalous dimensions to achieve our result. We show that the results
for the quark and gluon rapidity anomalous dimensions at four loops are related
by generalized Casimir scaling. Using the NLO rapidity anomalous dimension,
we perform the resummation of the Energy-Energy Correlation in the back-to-back
limit at NLL, achieving for the first time the resummation of an event
shape at this logarithmic order. We present numerical results and observe a
reduction of perturbative uncertainties on the resummed cross section to below
1%.Comment: 5 pages, 3 figures, 2 ancillary files. v2: corrected typo in tabled
values from ref [28] in eq. 10 and 11. Analytic formulae, EEC section and
ancillary files unchange
Soft Expansion of Double-Real-Virtual Corrections to Higgs Production at NLO
We present methods to compute higher orders in the threshold expansion for
the one-loop production of a Higgs boson in association with two partons at
hadron colliders. This process contributes to the NLO Higgs production
cross section beyond the soft-virtual approximation. We use reverse unitarity
to expand the phase-space integrals in the small kinematic parameters and to
reduce the coefficients of the expansion to a small set of master integrals. We
describe two methods for the calculation of the master integrals. The first was
introduced for the calculation of the soft triple-real radiation relevant to
NLO Higgs production. The second uses a particular factorization of the
three body phase-space measure and the knowledge of the scaling properties of
the integral itself. Our result is presented as a Laurent expansion in the
dimensional regulator, although some of the master integrals are computed to
all orders in this parameter.Comment: 30 page
Inclusive Production Cross Sections at N3LO
We present for the first time the inclusive cross section for associated
Higgs boson production with a massive gauge boson at
next-to-next-to-next-to-leading order in QCD. Furthermore, we introduce n3loxs,
a public, numerical program for the evaluation of inclusive cross sections at
the third order in the strong coupling constant. Our tool allows to derive
predictions for charged- and neutral-current Drell-Yan production, gluon- and
bottom-quark-fusion Higgs boson production and Higgs boson associated
production with a heavy gauge boson. We discuss perturbative and parton
distribution function (PDF) uncertainties of the aforementioned processes. We
perform a comparison of global PDF sets for a variety of process including
associated Higgs boson production and observe deviations among
predictions for several processes.Comment: 53 pages, 20 figures, 12 tables. Associated public computer program
to be found at https://github.com/jubaglio/n3lox
Higgs boson gluon-fusion production in QCD at Three Loops
We present the cross-section for the production of a Higgs boson at
hadron-colliders at next-to- next-to-next-to-leading order (N3LO) in
perturbative QCD. The calculation is based on a method to perform a series
expansion of the partonic cross-section around the threshold limit to an
arbitrary order. We perform this expansion to sufficiently high order to obtain
the value of the hadronic cross at N3LO in the large top-mass limit. For
renormalisation and factorisation scales equal to half the Higgs mass, the N3LO
corrections are of the order of +2.2%. The total scale variation at N3LO is 3%,
reducing the uncertainty due to missing higher order QCD corrections by a
factor of three.Comment: 5 pages, 3 figure
Higgs boson gluon-fusion production beyond threshold in N3LO QCD
In this article, we compute the gluon fusion Higgs boson cross-section at
N3LO through the second term in the threshold expansion. This calculation
constitutes a major milestone towards the full N3LO cross section. Our result
has the best formal accuracy in the threshold expansion currently available,
and includes contributions from collinear regions besides subleading
corrections from soft and hard regions, as well as certain logarithmically
enhanced contributions for general kinematics. We use our results to perform a
critical appraisal of the validity of the threshold approximation at N3LO in
perturbative QCD
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