82 research outputs found
HAWK 2.0: A Monte Carlo program for Higgs production in vector-boson fusion and Higgs strahlung at hadron colliders
The Monte Carlo integrator HAWK provides precision predictions for Higgs
production at hadron colliders in vector-boson fusion and Higgs strahlung, i.e.
in production processes where the Higgs boson is Attached to WeaK bosons. The
fully differential predictions include the full QCD and electroweak
next-to-leading-order corrections. Results are computed as integrated cross
sections and as binned distributions for important hadron-collider observables.Comment: 33 pages, 1 figur
ZZ production at the LHC: fiducial cross sections and distributions in NNLO QCD
We consider QCD radiative corrections to the production of four charged
leptons in the ZZ signal region at the LHC. We report on the complete
calculation of the next-to-next-to-leading order (NNLO) corrections to this
process in QCD perturbation theory. Numerical results are presented for
TeV, using typical selection cuts applied by the ATLAS and CMS
collaborations. The NNLO corrections increase the NLO fiducial cross section by
about , and they have a relatively small impact on the shape of the
considered kinematical distributions. In the case of the
distribution of the two Z candidates, the NNLO corrections improve the
agreement of the theoretical prediction with the CMS data.Comment: 9 pages, 3 figure
NLO QCD corrections to W+ W+ jj production in vector-boson fusion at the LHC
We present a next-to-leading-order QCD calculation for e+\nu e\mu+\nu\mu jj
production in vector-boson fusion, i.e. the scattering of two positively
charged W bosons at the LHC. We include the complete set of electroweak
leading-order diagrams for the six-particle final state and quantitatively
assess the size of the s-channel and interference contributions in VBF
kinematics. The calculation uses the complex-mass scheme to describe the
W-boson resonances and is implemented into a flexible Monte Carlo generator.
Using a dynamical scale based on the transverse momenta of the jets, the QCD
corrections stay below about 10% for all considered observables, while the
residual scale dependence is at the level of 1%.Comment: 60 page
Fully differential NNLO computations with MATRIX
We present the computational framework MATRIX which allows us to evaluate
fully differential cross sections for a wide class of processes at hadron
colliders in next-to-next-to-leading order (NNLO) QCD. The processes we
consider are and hadronic reactions involving Higgs and
vector bosons in the final state. All possible leptonic decay channels of the
vector bosons are included for the first time in the calculations, by
consistently accounting for all resonant and non-resonant diagrams, off-shell
effects and spin correlations. We briefly introduce the theoretical framework
MATRIX is based on, discuss its relevant features and provide a detailed
description of how to use MATRIX to obtain NNLO accurate results for the
various processes. We report reference predictions for inclusive and fiducial
cross sections of all the physics processes considered here and discuss their
corresponding uncertainties. MATRIX features an automatic extrapolation
procedure that allows us, for the first time, to control the systematic
uncertainties inherent to the applied NNLO subtraction procedure down to the
few permille level (or better).Comment: 76 pages, 2 figures, 11 table
Wgamma and Zgamma production at the LHC in NNLO QCD
We consider the production of and pairs at hadron
colliders. We report on the complete fully differential computation of
radiative corrections at next-to-next-to-leading order (NNLO) in QCD
perturbation theory. The calculation includes the leptonic decay of the vector
boson with the corresponding spin correlations, off shell effects and
final-state photon radiation. We present numerical results for collisions
at 7 and 8 TeV and we compare them with available LHC data. In the case of
production, the impact of NNLO corrections is generally moderate,
ranging from 8% to 18%, depending on the applied cuts. In the case of
production, the NNLO effects are more important, and range from 19% to 26%,
thereby improving the agreement of the theoretical predictions with the data.
As expected, the impact of QCD radiative corrections is significantly reduced
when a jet veto is applied.Comment: 27 pages, 11 figure
Transverse-momentum resummation for vector-boson pair production at NNLL+NNLO
We consider the transverse-momentum () distribution of and
boson pairs produced in hadron collisions. At small , the logarithmically
enhanced contributions due to multiple soft-gluon emission are resummed to all
orders in QCD perturbation theory. At intermediate and large values of ,
we consistently combine resummation with the known fixed-order results. We
exploit the most advanced perturbative information that is available at
present: next-to-next-to-leading logarithmic resummation combined with the
next-to-next-to-leading fixed-order calculation. After integration over ,
we recover the known next-to-next-to-leading order result for the inclusive
cross section. We present numerical results at the LHC, together with an
estimate of the corresponding uncertainties. We also study the rapidity
dependence of the spectrum and we consider efficiencies at
different orders of resummed and fixed-order perturbation theory.Comment: 25 pages, 11 figure
production at the LHC: fiducial cross sections and distributions in NNLO QCD
We report on the first fully differential calculation for
production in hadron collisions up to next-to-next-to-leading order (NNLO) in
QCD perturbation theory. Leptonic decays of the and bosons are
consistently taken into account, i.e. we include all resonant and non-resonant
diagrams that contribute to the process both in the same-flavour () and the
different-flavour () channel. Fiducial cross sections and
distributions are presented in the presence of standard selection cuts applied
in the experimental analyses by ATLAS and CMS at centre-of-mass
energies of 8 and 13\,TeV. As previously shown for the inclusive cross section,
NNLO corrections increase the NLO result by about , thereby leading to an
improved agreement with experimental data. The importance of NNLO accurate
predictions is also shown in the case of new-physics scenarios, where,
especially in high- categories, their impact can reach .
The availability of differential NNLO predictions will play a crucial role in
the rich physics programme that is based on precision studies of
signatures at the LHC.Comment: 38 pages, 18 figures, 8 table
NLO QCD corrections to pp->WW+jet+X
We report on the calculation of the next-to-leading order QCD corrections to
the production of W-boson pairs in association with a hard jet at hadron
colliders, which is an important source of background for Higgs and new-physics
searches. If a veto against the emission of a second hard jet is applied, the
corrections stabilize the leading-order prediction for the cross section
considerably.Comment: 6 pages, latex, 4 ps figures, to appear in the proceedings of the
"8th International Symposium on Radiative Corrections (RADCOR07)", Florence,
Italy, October 1-5, 200
production at the LHC: fiducial cross sections and distributions in NNLO QCD
We consider QCD radiative corrections to production at the LHC and
present the first fully differential predictions for this process at
next-to-next-to-leading order (NNLO) in perturbation theory. Our computation
consistently includes the leptonic decays of the bosons, taking into
account spin correlations, off-shell effects and non-resonant contributions.
Detailed predictions are presented for the different-flavour channel
at and TeV. In
particular, we discuss fiducial cross sections and distributions in the
presence of standard selection cuts used in experimental and analyses at the LHC. The inclusive cross section receives
large NNLO corrections, and, due to the presence of a jet veto, typical
fiducial cuts have a sizeable influence on the behaviour of the perturbative
expansion. The availability of differential NNLO predictions, both for
inclusive and fiducial observables, will play an important role in the rich
physics programme that is based on precision studies of signatures at
the LHC.Comment: 40 pages, 23 figures, 6 table
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