170 research outputs found
Standard Model Theory
The field of precision calculations for Standard Model processes at the LHC
has experienced enormous progress in recent years. This talk highlights some
examples from the physics of parton distribution functions, jets, electroweak
gauge bosons and Higgs bosons.Comment: 10 pages, 8 figures, latex, to appear in the Proceedings of the EPS
Conference on High Energy Physics (EPS-HEP), Venice, July 2017, reference
adde
Radiative corrections to W-pair production in e+e- annihilation
The status of precision calculations for the processes e+e- --> WW --> 4
fermions is reviewed, paying particular attention to questions of gauge
invariance and recent progress concerning photonic radiative corrections.Comment: 16 pages, latex, 4 postscript figures, contribution to the
proceedings of "IVth International Symposium on Radiative Corrections, RADCOR
98", September 1998, Barcelona, Spai
Radiative corrections to the neutral-current Drell-Yan process in the Standard Model and its minimal supersymmetric extension
An adequate description of the neutral-current Drell-Yan process at the
Tevatron and the LHC, in particular, requires the inclusion of electroweak
radiative corrections. We extend earlier work in this direction in various
ways. First, we define and numerically compare different methods to describe
the Z-boson resonance including next-to-leading order electroweak corrections;
moreover, we provide explicit analytical expressions for those. Second, we pay
particular attention to contributions from photon-photon and photon-quark
collisions, which involve photons in the initial state, and work out how their
impact can be enhanced by selection cuts. Third, we supplement the O(\alpha)
corrections by universal electroweak effects of higher order, such as universal
two-loop contributions from \Delta\alpha and \Delta\rho, and the leading
two-loop corrections in the high-energy Sudakov regime as well as multi-photon
radiation off muons in the structure-function approach. Finally, we present
results on the complete next-to-leading order electroweak and QCD corrections
within the minimal supersymmetric extension of the Standard Model.Comment: 57 pages, latex, 19 figures, 7 tables; photon PDF factorization
changed; minor corrections; version to appear in JHE
Mixed QCD-electroweak O(\alpha_s\alpha) corrections to Drell-Yan processes in the resonance region: pole approximation and non-factorizable corrections
Drell-Yan-like W-boson and Z-boson production in the resonance region allows
for high-precision measurements that are crucial to carry experimental tests of
the Standard Model to the extremes, such as the determination of the W-boson
mass and the effective weak mixing angle. In this article, we establish a
framework for the calculation of the mixed QCD-electroweak O(\alpha_s\alpha)
corrections to Drell-Yan processes in the resonance region, which are one of
the main remaining theoretical uncertainties. We describe how the Standard
Model prediction can be successfully performed in terms of a consistent
expansion about the resonance poles, which classifies the corrections in terms
of factorizable and non-factorizable contributions. The former can be
attributed to the W/Z production and decay subprocesses individually, while the
latter link production and decay by soft-photon exchange. At next-to-leading
order we compare the full electroweak corrections with the pole-expanded
approximations, confirming the validity of the approximation. At
O(\alpha_s\alpha), we describe the concept of the expansion and explicitly give
results on the non-factorizable contributions, which turn out to be
phenomenologically negligible. Our results, thus, demonstrate that for
phenomenological purposes the O(\alpha_s\alpha) corrections can be factorized
into terms associated with initial-state and/or final-state corrections.
Moreover, we argue that the factorization properties of the non-factorizable
corrections at O(\alpha_s\alpha) from lower-order O(\alpha_s) graphs generalize
to any order in O(\alpha_s^n\alpha).Comment: 56 pages, 22 figure
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
Next-to-leading-order QCD and electroweak corrections to WWW production at proton-proton colliders
Triple-W-boson production in proton-proton collisions allows for a direct
access to the triple and quartic gauge couplings and provides a window to the
mechanism of electroweak symmetry breaking. It is an important process to test
the Standard Model (SM) and might be background to physics beyond the SM. We
present a calculation of the next-to-leading order (NLO) electroweak
corrections to the production of WWW final states at proton-proton colliders
with on-shell W bosons and combine the electroweak with the NLO QCD
corrections. We study the impact of the corrections to the integrated cross
sections and to kinematic distributions of the W bosons. The electroweak
corrections are generically of the size of 5-10% for integrated cross sections
and become more pronounced in specific phase-space regions. The real
corrections induced by quark-photon scattering turn out to be as important as
electroweak loops and photon bremsstrahlung corrections, but can be reduced by
phase-space cuts. Considering that prior determinations of the photon parton
distribution function (PDF) involve rather large uncertainties, we compare the
results obtained with different photon PDFs and discuss the corresponding
uncertainties in the NLO predictions. Moreover, we determine the scale and
total PDF uncertainties at the LHC and a possible future 100 TeV pp collider.Comment: 15 pages, 9 figures, 5 tables, revised version, published in JHE
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