48 research outputs found
Track 3: Computations in theoretical physics -- techniques and methods
Here, we attempt to summarize the activities of Track 3 of the 17th
International Workshop on Advanced Computing and Analysis Techniques in Physics
Research (ACAT 2016).Comment: 10 pages, 3 figures, to appear in the proceedings of ACAT 201
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
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
NNLO Antenna Subtraction with One Hadronic Initial State
In this talk we present the extension of the antenna subtraction method to
include initial states containing one hadron at NNLO. We sketch the
requirements for the different necessary subtraction terms, and we explain how
the antenna functions are integrated over the appropriate phase space by
reducing the integrals to a small set of master integrals. Where applicable,
our results for the integrated antennae were cross-checked against the known
NNLO coefficient functions for deep inelastic scattering processes.Comment: 6 pages, 1 figure. Talk given at RADCOR 2009 - 9th International
Symposium on Radiative Corrections (Applications of Quantum Field Theory to
Phenomenology) October 25 - 30 200
NLO QCD corrections to Higgs boson production in association with a top quark pair and a jet
We present the calculation of the cross section for Higgs boson production in
association with a top quark pair plus one jet, at next-to-leading-order (NLO)
accuracy in QCD. All mass dependence is retained without recurring to any
approximation. After including the complete NLO QCD corrections, we observe a
strong reduction in the scale dependence of the result. We also show
distributions for the invariant mass of the top quark pair, with and without
the additional jet, and for the transverse momentum and the pseudorapidity of
the Higgs boson. Results for the virtual contributions are obtained with a
novel reduction approach based on integrand decomposition via Laurent
expansion, as implemented in the library Ninja. Cross sections and differential
distributions are obtained with an automated setup which combines the GoSam and
Sherpa frameworks.Comment: 5 pages, 5 figures. v3: corrected benchmark point in the appendi
Multi-leg One-loop Massive Amplitudes from Integrand Reduction via Laurent Expansion
We present the application of a novel reduction technique for one-loop
scattering amplitudes based on the combination of the integrand reduction and
Laurent expansion. We describe the general features of its implementation in
the computer code NINJA, and its interface to GoSam. We apply the new reduction
to a series of selected processes involving massive particles, from six to
eight legs.Comment: v3: 39 pages, minor typos and one benchmark point correcte