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