arXiv subjects

A. Denner

Publications and source records attributed to A. Denner.

100 records · Page 6Linked to original sources

arXiv1996

Electroweak Radiative Corrections to AA -> W+W-

We discuss the complete virtual and soft-photonic O(alpha) corrections to AA -> W+W- within the electroweak Standard Model for arbitrary polarized photons. In the on-shell renormalization scheme for fixed M_W no leading corrections associated with the running of alpha or heavy top-quark and Higgs-boson masses occur. The corrections turn out to be of the order of 10%, but can become much larger where the lowest-order cross-sections are suppressed.

hep-ph↗

arXiv1995

Radiative Corrections to $γγ\to t \bar t$ in the Electroweak Standard Model

The cross-section for $γγ\to t \bar t$ with arbitrary polarized photons is calculated within the electroweak Standard Model including the complete virtual and soft-photonic $O(α)$ corrections. We present a detailed numerical discussion of the radiative corrections with particular emphasis on the purely weak corrections. These are usually of the order of 1--10\% for energies up to 1 TeV. For unpolarized or equally polarized photons they reach almost 10\% close to threshold. The large corrections cannot be traced back to a universal origin like the running of $α$ or the $ρ$-parameter. Apart from the energy region around the Higgs resonance $(γγ\to H^*\to t\bar t)$ the weak corrections are widely independent of the Higgs-boson mass.

hep-ph↗

arXiv1995

Radiative Corrections to $γγ\to W^+ W^-$ in the Electroweak Standard Model

The cross-section for $γγ\to W^+ W^-$ with arbitrary polarized photons and W bosons is calculated within the electroweak Standard Model including the complete virtual and soft-photonic ${\cal O}(α)$ corrections. We present a detailed numerical discussion of the complete radiative corrections and an analytical investigation of the leading corrections. It turns out that in the on-shell renormalization scheme for fixed $M_W$ no leading corrections associated with the running of $α$ or heavy top-quark and Higgs-boson masses occur. The corrections are typically of the order of 10\%. They reach, however, larger values where the lowest-order cross-sections are suppressed.

hep-ph↗

arXiv1994

Probing the Higgs mechanism via $γγ\to W^+W^-$

We investigate the sensitivity of the reaction $γγ\to W^+W^-$ to the Higgs sector based on the complete one-loop corrections in the minimal Standard Model and the gauged non-linear $σ$-model. While this sensitivity is very strong for the suppressed cross-section of equally polarized photons and longitudinal W bosons, it is only marginal for the dominant mode of transverse polarizations. The corrections within the $σ$-model turn out to be UV-finite in accordance with the absence of $\log\MH$ terms in the Standard Model with a heavy Higgs boson.

hep-ph↗

arXiv1994

Application of the Background-Field Method to the electroweak Standard Model

Application of the background-field method yields a gauge-invariant effective action for the electroweak Standard Model, from which simple QED-like Ward identities are derived. As a consequence of these Ward identities, the background-field Green functions are shown to possess very desirable theoretical properties. The renormalization of the Standard Model in the background-field formalism is studied. A consistent on-shell renormalization procedure retaining the full gauge symmetry is presented. The structure of the counterterms is shown to greatly simplify compared to the conventional formalism. A complete list of Feynman rules for the Standard Model in the background-field method is given for arbitrary values of a quantum gauge parameter including all counterterms necessary for one-loop calculations.

hep-ph↗

arXiv1994

Green functions from a gauge-invariant effective action for the electroweak Standard Model

Application of the background-field method to the electroweak Standard-Model yields a gauge-invariant effective action giving rise to simple Ward identities. We find that in the background-field `t Hooft-Feynman gauge the resulting vertex functions are exactly those that are obtained using the pinch technique. Thus, the background-field method provides a general framework that generalizes the pinch technique directly and uniquely to arbitrary Green functions and arbitrary orders of perturbation theory. Moreover, the desirable properties of the pinch-technique vertex functions hold for arbitrary gauge parameters and have a simple explanation within the background- field method.

hep-ph↗

arXiv1994

Gauge Invariance of Green Functions: Background-Field Method versus Pinch Technique

Application of the background-field method to QCD and the electroweak Standard Model yields gauge-invariant effective actions giving rise to simple Ward identities. Within this method, we calculate the quantities that have been treated in the literature using the pinch technique. Putting the quantum gauge parameter equal to one, we recover the pinch-technique results as a special case of the background-field method. The one-particle-irreducible Green functions of the background-field method fulfil for arbitrary gauge parameters the desirable theoretical properties that have been noticed within the pinch technique. Therefore the background-field formalism provides a general framework for the direct calculation of well-behaved Green functions. Within this formalism, the pinch technique appears as one of arbitrarily many equivalent possibilities.

hep-ph↗

arXiv1993

Gauge-Boson Production in Electron-Photon Collisions

We summarize results for the processes $e^-γ\to νW^-, e^-Z, e^-γ$ within the electroweak Standard Model. We discuss the essential features of the corresponding lowest-order cross-sections and present numerical results for the unpolarized cross-sections including the complete $O(α)$ virtual, soft-photonic, and hard-photonic corrections. While at low energies the weak corrections are dominated by the leading universal corrections, at high energies we find large, non-universal corrections, which arise from vertex and box diagrams involving non-Abelian gauge couplings.

hep-ph↗

arXiv1993

Theoretical Predictions for W-Pair Production

We review the status of theoretical predictions for W-pair production at high energies. We discuss a systematic scenario towards a Monte-Carlo generator for e^+e^- --> 4f(γ), which meets the experimental requirements. In particular we summarize the recent developments in this field.

hep-ph↗

arXiv1993

$Ø(\GF^2\Mt^4)$ Electroweak Radiative Corrections to the $\PZ\Pb\Pbbar$ Vertex

The leading heavy-top two-loop corrections to the \Zbb~vertex are determined from a direct evaluation of the corresponding Feynman diagrams in the large \Mt~limit. %The calculation is done in the naive %dimensional regularization scheme with anticommuting $\ga_5$. The leading one-loop top-mass effect is enhanced by $[1+\GF\Mt^2(9-π^2/3)/(8π^2\sqrt{2})]$. Our calculation confirms a recent result of Barbieri et al.

hep-ph↗