298 research outputs found
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
Anomalous triple-gauge-boson interactions in vector-boson pair production with RECOLA2
Diboson production at the LHC is a process of great importance both in the
context of tests of the SM and for direct searches for new physics. In this
paper we present a phenomenological study of WW, WZ, and ZZ production
considering event selections of interest for the anomalous
triple-gauge-boson-coupling searches at the LHC: we provide theoretical
predictions within the Standard Model at NLO QCD and NLO EW accuracy and study
the effect of the anomalous triple-gauge-boson interactions at NLO QCD. For WW
and ZZ production, the contribution of the gluon-initiated loop-induced
processes is included. Anomalous triple-gauge-boson interactions are
parametrized in the EFT framework. This paper is the first application of
RECOLA2 in the EFT context.Comment: 36 pages, 56 pdf figures, latex. Corrected typo in Eq.(3.2). One
reference added. Published versio
Electroweak Sudakov Corrections to New Physics Searches at the CERN LHC
We compute the one-loop electroweak Sudakov corrections to the production
process Z (nu bar{nu}) + n jets, with n = 1,2,3, in p p collisions at the LHC.
It represents the main irreducible background to new physics searches at the
energy frontier. The results are obtained at the leading and next-to-leading
logarithmic accuracy by implementing the general algorithm of Denner-Pozzorini
in the event generator for multiparton processes ALPGEN. For the standard
selection cuts used by ATLAS and CMS collaborations, we show that the Sudakov
corrections to the relevant observables can grow up to - 40% at sqrt{s} = 14
TeV. We also include the contribution due to undetected real radiation of
massive gauge bosons, to show to what extent the partial cancellation with the
large negative virtual corrections takes place in realistic event selections.Comment: 5 pages, 3 figures, 1 table. Extended discussion on real radiation
processes. Added references. Results unchanged. Version to appear in Phys.
Rev. Let
W gamma production in hadronic collisions using the POWHEG+MiNLO method
We detail a calculation of W gamma production in hadronic collision, at
Next-to-Leading Order (NLO) QCD interfaced to a shower generator according to
the POWHEG prescription supplemented with the MiNLO procedure. The fixed order
result is matched to an interleaved QCD+QED parton shower, in such a way that
the contribution arising from hadron fragmentation into photons is fully
modeled. In general, our calculation illustrates a new approach to the fully
exclusive simulation of prompt photon production processes accurate at the NLO
level in QCD. We compare our predictions to those of the NLO program MCFM,
which treats the fragmentation contribution in terms of photon fragmentation
functions. We also perform comparisons to available LHC data at 7 TeV, for
which we observe good agreement, and provide phenomenological results for
physics studies of the W gamma production process at the Run II of the LHC. The
new tool, which includes W leptonic decays and the contribution of anomalous
gauge couplings, allows a fully exclusive, hadron-level description of the W
gamma process, and is publicly available at the repository of the POWHEG BOX.
Our approach can be easily adapted to deal with other relevant isolated photon
production processes in hadronic collisions.Comment: 38 pages, 5 Tables, 9 Figures. Final version published in JHEP.
Acknowledgments to Galileo Galilei Institute for Theoretical Physics and to
INFN adde
Effects of anomalous triple-gauge-boson interactions in diboson production with RECOLA2
Diboson production processes are of great importance in high-energy physics
and a precise theoretical knowledge of VV production is mandatory not only in
view of precision tests of the Standard Model but also in the one of new
physics searches. We present results of arXiv:1804.01477, where we computed the
NLO QCD and NLO electroweak corrections to diboson production processes at the
LHC including the effect of the anomalous triple-gauge-boson interactions at
NLO QCD accuracy. The anomalous triple-gauge-boson interactions are
parametrized in terms of higher-dimensional operators in the effective field
theory framework. Our calculation is the first application of Recola2 to
effective field theory models.Comment: Talk presented at Loops and Legs in Quantum Field Theory (LL2018), 29
April 2018 - 04 May 2018, St. Goar, Germany. Submitted to PoS. arXiv admin
note: text overlap with arXiv:1807.1019
Precision Measurement of the W-Boson Mass: Theoretical Contributions and Uncertainties
We perform a comprehensive analysis of electroweak, QED and mixed
QCD-electroweak corrections underlying the precise measurement of the W-boson
mass M_W at hadron colliders. By applying a template fitting technique, we
detail the impact on M_W of next-to-leading order electroweak and QCD
corrections, multiple photon emission, lepton pair radiation and factorizable
QCD-electroweak contributions. As a by-product, we provide an up-to-date
estimate of the main theoretical uncertainties of perturbative nature. Our
results can serve as a guideline for the assessment of the theoretical
systematics at the Tevatron and LHC and allow a more robust precision
measurement of the W-boson mass at hadron colliders.Comment: 51 pages, 10 figures and 16 tables. Minor corrections: new citations
and reference to the svn revisions of the POWHEG code. Numerical results and
conclusions unchange
An event generator for same-sign W-boson scattering at the LHC including electroweak corrections.
In this article we present an event generator based on the Monte Carlo program Powheg in combination with the matrix-element generator Recola. We apply it to compute NLO electroweak corrections to same-sign W-boson scattering, which have been shown to be large at the LHC. The event generator allows for the generation of unweighted events including the effect of the NLO electroweak corrections matched to a QED parton shower and interfaced to a QCD parton shower. In view of the expected experimental precision of future measurements, the use of such a tool will be indispensable
DEFINITION OF THE FLEXIBLE AIRCRAFT LONGITUDINAL MODEL FOR A PRELIMINARY CONTROL DESIGN
Developing control system of high aspect ratio aircraft can be challenging due to flexibility involved
in the control loop design. A model based approach can be straightforward to tune the control system
parameters and, to this aim, a reliable aircraft flexible model is necessary. This paper aims to present
the approach followed to design the longitudinal control strategy considering the aircraft simulator in
the loop. The elastic modes are calculated from the lumped mass geometrical model and an
aerodynamic properties from a reference aircraft. The approach and the model validation have been
done in partnership with Leonardo Aircraft, as a thesis topic. Beginning with verification of the trim
conditions, the flexible dynamic modes are compared to the rigid ones in order to highlight the
relevant changes in the aircraft modes. A preliminary design of the longitudinal control strategy is
herein proposed to achieve the dynamic response objectives
Next-to-next-to-leading order event generation for production with decay
We consider the Higgsstrahlung process in hadronic collisions and present the
computation of next-to-next-to-leading order predictions matched to parton
showers for both production and decay employing the
MiNNLO method. We present predictions for and
production including spin correlations and off-shell effects by calculating the
full processes , and in the narrow-width approximation
for the Higgs boson. For the process, NNLO+PS accuracy in production
and decay is achieved for the first time. Our calculations are validated
against earlier simulations in the NNLOPS approach that includes NNLO
corrections via multi-differential reweighting. The new MiNNLO
generators for these processes, which evaluate NNLO corrections on-the-fly in
the event generation, will supersede those earlier calculations. Our
predictions are in good agreement with recent measurements of the
Higgsstrahlung cross sections.Comment: 37 pages, 8 figures, 4 table
Electroweak Corrections at High Energies
We present a survey of the most abundant processes at the LHC for sensitivity
to electroweak corrections at \sqrt{s} = 8, 14, 33, and 100 TeV proton-proton
collision energies. The processes studied are pp -> dijet, inclusive W and Z,
W/Z+jets, and WW. In each case we compare the experimental uncertainty in the
highest kinematic regions of interest with the relative magnitude of
electroweak corrections and fixed-order \alpha_S calculations.Comment: Contribution to the Snowmass-2013 report of the QCD Working Group. 15
pages, 14 figures, 5 tables. Version 2: Added a new section 4A and updated
the author list, acknowledgements, and references. Version 3: Added a new
reference Ref.[36
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