1,034 research outputs found
Wbbj production at NLO with POWHEG+MiNLO
We present a next-to-leading order plus parton-shower event generator for the
production of a W boson plus two bottom quarks and a jet at hadron colliders,
implemented in the POWHEG BOX framework. Bottom-mass effects and spin
correlations of the decay products of the W boson are fully taken into account.
The code has been automatically generated using the two available interfaces to
MadGraph4 and GoSam, the last one updated to a new version. We have applied the
MiNLO prescription to our Wbbj calculation, obtaining a finite differential
cross section also in the limit of vanishing jet transverse momentum.
Furthermore, we have compared several key distributions for Wbbj production
with those generated with a next-to-leading order plus parton-shower event
generator for Wbb production, and studied their factorization- and
renormalization-scale dependence. Finally, we have compared our results with
recent experimental data from the ATLAS and CMS Collaborations.Comment: Version as accepted for publication. Added references, one table and
one figure. All the rest is the same as version
Associated ZH production at hadron colliders: the fully differential NNLO QCD calculation
We consider Standard Model Higgs boson production in association with a Z
boson in hadron collisions. We present a fully exclusive computation of QCD
radiative corrections up to next-to-next-to-leading order (NNLO). Our
calculation includes the Higgs boson decay to bottom quarks (b) in
next-to-leading order QCD and the leptonic decay of the Z boson with
finite-width effects and spin correlations. The computation is implemented in a
parton level Monte Carlo program that makes possible to consider arbitrary
kinematical cuts on the final-state leptons, the b jets and the associated QCD
radiation, and to compute the corresponding distributions in the form of bin
histograms. We assess the impact of QCD radiative effects in the boosted
kinematics at the LHC and show that the inclusion of the NNLO corrections is
crucial to control the pT spectrum of the Higgs boson candidate.Comment: 10 pages, 2 figure
Higher-order QCD effects for associated WH production and decay at the LHC
We consider Standard Model Higgs boson production in association with a W
boson in hadron collisions. We supplement the fully exclusive perturbative
computation of QCD radiative effects up to next-to-next-to-leading order (NNLO)
with the computation of the decay of the Higgs boson into a bb pair at
next-to-leading order (NLO). We consider the selection cuts that are typically
applied in the LHC experimental analysis, and we compare our fixed-order
predictions with the results obtained with the MC@NLO event generator. We find
that NLO corrections to the H -> bb decay can be important to obtain a reliable
pT spectrum of the Higgs boson, but that, in the cases of interest, their
effect is well accounted for by the parton shower Monte Carlo. NNLO corrections
to the production process typically decrease the cross section by an amount
which depends on the detail of the applied cuts, but they have a mild effect on
the shape of the Higgs pT spectrum. We also discuss the effect of QCD radiative
corrections on the invariant mass distribution of the Higgs candidate.Comment: 18 pages, 7 figures. References and figure added. Version published
on JHE
Single top theory
I breafly discuss very recent progress in the theoretical description of
Standard Model single top production at hadron colliders
Associated production of a Higgs boson decaying into bottom quarks at the LHC in full NNLO QCD
We consider the production of a Standard Model Higgs boson decaying to bottom
quarks in association with a vector boson W/Z in hadron collisions. We present
a fully exclusive calculation of QCD radiative corrections both for the
production cross section and for the Higgs boson decay rate up to
next-to-next-to-leading order (NNLO) accuracy. Our calculation also includes
the leptonic decay of the vector boson with finite-width effects and spin
correlations. We consider typical kinematical cuts applied in the experimental
analyses at the Large Hadron Collider (LHC) and we find that the full NNLO QCD
corrections significantly decrease the accepted cross section and have a
substantial impact on the shape of distributions. We point out that these
additional effects are essential to obtain precise theoretical predictions to
be compared with the LHC data.Comment: Additional quantitative information included in the figures, minor
changes in the text, version published on PL
Automation of electroweak corrections for LHC processes
For the Run 2 of the LHC next-to-leading order electroweak corrections will
play an important role. Even though they are typically moderate at the level of
total cross sections they can lead to substantial deviations in the shapes of
distributions. In particular for new physics searches but also for a precise
determination of Standard Model observables their inclusion in the theoretical
predictions is mandatory for a reliable estimation of the Standard Model
contribution. In this article we review the status and recent developments in
electroweak calculations and their automation for LHC processes. We discuss
general issues and properties of NLO electroweak corrections and present some
examples, including the full calculation of the NLO corrections to the
production of a W boson in association with two jets computed using GoSaM
interfaced to MadDipole.Comment: LaTex, 60 pages, 8 Figure
Single top theory
I breafly discuss very recent progress in the theoretical description of
Standard Model single top production at hadron colliders
HW/HZ + 0 and 1 jet at NLO with the POWHEG BOX interfaced to GoSam and their merging within MiNLO
We present a generator for the production of a Higgs boson H in association
with a vector boson V=W or Z (including subsequent V decay) plus zero and one
jet, that can be used in conjunction with general-purpose shower Monte Carlo
generators, according to the POWHEG method, as implemented within the POWHEG
BOX framework. We have computed the virtual corrections using GoSam, a program
for the automatic construction of virtual amplitudes. In order to do so, we
have built a general interface of the POWHEG BOX to the GoSam package. With
this addition, the construction of a POWHEG generator within the POWHEG BOX is
now fully automatized, except for the construction of the Born phase space. Our
HV + 1 jet generators can be run with the recently proposed MiNLO method for
the choice of scales and the inclusion of Sudakov form factors. Since the HV
production is very similar to V production, we were able to apply an improved
MiNLO procedure, that was recently used in H and V production, also in the
present case. This procedure is such that the resulting generator achieves NLO
accuracy not only for inclusive distributions in HV + 1 jet production but also
in HV production, i.e. when the associated jet is not resolved, yielding a
further example of matched calculation with no matching scale.Comment: 22 pages, 18 figures. Version accepted for publication on JHE
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