Search results for "Electroweak"
showing 10 items of 744 documents
W+W−Production at Hadron Colliders in Next to Next to Leading Order QCD
2014
Charged gauge boson pair production at the Large Hadron Collider allows detailed probes of the fundamental structure of electroweak interactions. We present precise theoretical predictions for on-shell W+ W- production that include, for the first time, QCD effects up to next to next to leading order in perturbation theory. As compared to next to leading order, the inclusive W+ W- cross section is enhanced by 9% at 7 TeV and 12% at 14 TeV. The residual perturbative uncertainty is at the 3% level. The severe contamination of the W+ W- cross section due to top-quark resonances is discussed in detail. Comparing different definitions of top-free W+ W- production in the four and five flavor numbe…
Exclusive radiative decays of W and Z bosons in QCD factorization
2015
We present a detailed theoretical analysis of very rare, exclusive hadronic decays of the electroweak gauge bosons V=W, Z from first principles of QCD. Our main focus is on the radiative decays V->M+gamma, in which M is a pseudoscalar or vector meson. At leading order in an expansion in powers of Lambda_{QCD}/m_V the decay amplitudes can be factorized into convolutions of calculable hard-scattering coefficients with the leading-twist light-cone distribution amplitude of the meson M. Power corrections to the decay rates arise first at order (Lambda_{QCD}/m_V)^2. They can be estimated in terms of higher-twist distribution amplitudes and are predicted to be tiny. We include one-loop O(alpha…
Precision physics with inclusive QCD processes
2021
The inclusive production of hadrons through electroweak currents can be rigorously analysed with short-distance theoretical tools. The associated observables are insensitive to the involved infrared behaviour of the strong interaction, allowing for very precise tests of Quantum Chromodynamics. The theoretical predictions for $\sigma(e^+e^-\to\mathrm{hadrons})$ and the hadronic decay widths of the $\tau$ lepton and the $Z$, $W$ and Higgs bosons have reached an impressive accuracy of $\mathcal{O}(\alpha_s^4)$. Precise experimental measurements of the $Z$ and $\tau$ hadronic widths have made possible the accurate determination of the strong coupling at two very different energy scales, providi…
Prospects for charged current deep-inelastic scattering off polarized nucleons at a future electron-ion collider
2013
We present a detailed phenomenological study of charged-current-mediated deep-inelastic scattering off longitudinally polarized nucleons at a future Electron-Ion Collider. A new version of the event generator package DJANGOH, extended by capabilities to handle processes with polarized nucleons, is introduced and used to simulate charged current deep-inelastic scattering including QED, QCD, and electroweak radiative effects. We carefully explore the range of validity and the accuracy of the Jacquet-Blondel method to reconstruct the relevant kinematic variables from the measured hadronic final state in charged current events, assuming realistic detector performance parameters. Finally, we est…
QCD JETS AT HERA I.: O(αs) RADIATIVE CORRECTIONS TO ELECTROWEAK CROSS SECTIONS AND JET RATES
1989
We present the complete O(αs) corrections to the electroweak cross sections of both neutral current and charged current deep inelastic e±p scattering including lepton polarization effects. Changes in the cross section due to the inclusion of next-to-leading-log (NLL) effects are parametrized by K factors, which are defined as the ratio of the NLL O(αs) cross sections and the Born cross section. Using the standard redefinition scheme of the parton densities, we find that the K factors deviate substantially from unity for small values of the Bjorken-Scaling variable x. We also elaborate on problems that arise when defining jet cross sections in ep scattering and present numerical results for…
The Institute for Nuclear Physics at the University of Mainz
2008
MAMI, the MAinz MIcrotron, has become a synonym for a cw electron scattering facility in the 1.5 14;GeV range with an outstanding beam quality and reliability. The Institute for Nuclear Physics (IKP) at the Johannes Gutenberg-University of Mainz, the home of MAMI, has developed and built this cascade of four recirculating machines for precision scattering experiments mostly with polarized electrons and photons for research in the field of hadron and nuclear physics. The central physics topic is the investigation of strongly interacting systems with the electroweak probe. This field, nowadays called strong QCD, which means QCD in the strongly coupled, non perturbative regime, still poses a n…
NLO corrections to processes with electroweak bosons at hadron colliders
2015
For many processes with electroweak bosons in the final state, next-to-leading order QCD and, in some cases, electroweak corrections have been calculated for differential cross sections at hadron colliders. The calculational techniques and some phenomenological implications are reviewed in this contribution. Processes discussed include vector boson fusion and vector boson scattering, production of two and three electroweak bosons, potentially with jets, (VV j, VV jj and VVV events) and some Higgs production processes. All QCD corrections are implemented in the publicly available VBFNLO program package.
Electroweak Higgs Boson Plus Three Jet Production at Next-to-Leading-Order QCD
2013
We calculate next-to-leading order (NLO) QCD corrections to electroweak Higgs boson plus three jet production. Both vector boson fusion (VBF) and Higgs-strahlung type contributions are included along with all interferences. The calculation is implemented within the MATCHBOX NLO framework of the HERWIG++ event generator.
Kaon Decays in the Standard Model
2011
A comprehensive overview of kaon decays is presented. The Standard Model predictions are discussed in detail, covering both the underlying short-distance electroweak dynamics and the important interplay of QCD at long distances. Chiral perturbation theory provides a universal framework for treating leptonic, semileptonic and nonleptonic decays including rare and radiative modes. All allowed decay modes with branching ratios of at least 10^(-11) are analyzed. Some decays with even smaller rates are also included. Decays that are strictly forbidden in the Standard Model are not considered in this review. The present experimental status and the prospects for future improvements are reviewed.
Evidence ofWγγProduction inppCollisions ats=8 TeVand Limits on Anomalous Quartic Gauge Couplings with the ATLAS Detector
2015
This Letter reports evidence of triple gauge boson production pp -> W(l nu)gamma gamma + X, which is accessible for the first time with the 8 TeV LHC data set. The fiducial cross section for this process is measured in a data sample corresponding to an integrated luminosity of 20.3 fb(-1), collected by the ATLAS detector in 2012. Events are selected using the W boson decay to e nu or mu nu as well as requiring two isolated photons. The measured cross section is used to set limits on anomalous quartic gauge couplings in the high diphoton mass region.