Radiative corrections to W+W− → W+W− in the electroweak standard model

Denner, Ansgar; Hahn, Thomas

doi:10.1016/s0550-3213(98)00287-9

Cited by 69 publications

(58 citation statements)

References 56 publications

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“…The authors of Ref. [61], for example, have shown that unitarity-breaking terms can show up in the final form for the amplitude. From a formal perspective, indeed, transition amplitudes have to be defined in terms of asymptotic states containing stable particles only.…”

Section: Higgs-boson Mass and Wave-function Renormalizationmentioning

confidence: 99%

NNLO computational techniques: The cases and

et al. 2009

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A large set of techniques needed to compute decay rates at the two-loop level are derived and systematized. The main emphasis of the paper is on the two Standard Model decays H → γγ and H → gg. The techniques, however, have a much wider range of application: they give practical examples of general rules for two-loop renormalization; they introduce simple recipes for handling internal unstable particles in two-loop processes; they illustrate simple procedures for the extraction of collinear logarithms from the amplitude. The latter is particularly relevant to show cancellations, e.g. cancellation of collinear divergencies. Furthermore, the paper deals with the proper treatment of non-enhanced two-loop QCD and electroweak contributions to different physical (pseudo-)observables, showing how they can be transformed in a way that allows for a stable numerical integration. Numerical results for the two-loop percentage corrections to H → γγ, gg are presented and discussed. When applied to the process pp → gg + X → H + X, the results show that the electroweak scaling factor for the cross section is between −4% and +6% in the range 100 GeV < M H < 500 GeV, without incongruent large effects around the physical electroweak thresholds, thereby showing that only a complete implementation of the computational scheme keeps two-loop corrections under control.

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Section: Higgs-boson Mass and Wave-function Renormalizationmentioning

confidence: 99%

NNLO computational techniques: The cases and

et al. 2009

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“…Moreover very subtle gauge cancellations take place especially as the energy of the participating W 's increases. The most complete calculation has been performed in [163] and the code is freely available at www.hep-processes.de. However, hard photon radiation is not included.…”

Section: Eγ → Ezmentioning

confidence: 99%

“…However, hard photon radiation is not included. Following [163] we have compared our results with those of the code by requiring a cut on the forward-backward direction such that the integration over the scattering angle is over 10…”

Section: Eγ → Ezmentioning

confidence: 99%

Automatic calculations in high energy physics and GRACE at one-loop

Bélanger¹,

Boudjema²,

et al. 2006

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We describe the main building blocks of a generic automated package for the calculation of Feynman diagrams. These blocks include the generation and creation of a model file, the graph generation, the symbolic calculation at an intermediate level of the Dirac and tensor algebra, implementation of the loop integrals, the generation of the matrix elements or helicity amplitudes, methods for the phase space integrations and eventually the event generation. The report focuses on the fully automated systems for the calculation of physical processes based on the experience in developing GRACE-loop which is a general purpose code applicable to one-loop corrections in the Standard Model. As such, a detailed description of the renormalisation procedure in the Standard Model is given emphasizing the central role played by the non-linear gauge fixing conditions for the construction of such automated codes. These new gauge-fixing conditions are used as a very efficient means to check the results of large scale automated computations in the Standard Model. Their need is better appreciated when it comes to devising efficient and powerful algorithms for the reduction of the tensorial structures of the loop integrals and the reduction of the N > 4 point-function to lower rank integrals. A new technique for these reduction algorithms is described. Explicit formulae for all two-point functions in a generalised non-linear gauge are given, together with the complete set of counterterms. We also show how infrared divergences are dealt with in the system. We give a comprehensive presentation of some systematic test-runs which have been performed at the one-loop level for a wide variety of two-to-two processes to show the validity of the gauge check. These cover fermion-fermion scattering, gauge boson scattering into fermions, gauge bosons and Higgs bosons scattering processes. Comparisons with existing results on some one-loop computation in the Standard Model show excellent agreement. These include e + e − → tt, W + W − , ZH; γγ → tt, W + W − ; eγ → eZ, νW and W + W − → W + W − . We also briefly recount some recent development concerning the calculation of one-loop corrections to 3 body final states cross sections in e + e − with the help of an automated system.

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“…We should give a second thought to results of Lee, Quigg, Thacker, Weldon, Chanowitz, Gaillard, Gounaris, Kögerler, Neufeld, Denner, Dittmaier, Hahn et al [6], [7] and look if there is some clue concerning the above listed questions. Maybe lattice simulations can help in the study of the transition to M = 0.…”

Section: Open Problemsmentioning

confidence: 97%

Of higgs, unitarity and other questions

Bettinelli

Ferrari

Quadri

2011

Proc. Steklov Inst. Math.

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On the verge of conclusive checks on the Standard Model by the LHC, we discuss some of the basic assumptions. The reason for this analysis stems from a recent proposal of an Electroweak Model based on a nonlinearly realized gauge group SU (2) ⊗ U (1), where, in the perturbative approximation, there is no Higgs boson. The model enjoys the Slavnov-Taylor identities and therefore the perturbative unitarity. On the other hand, it is commonly believed that the existence of the Higgs boson is entangled with the property of unitarity, when high energy processes are considered. The argument is based mostly on the Froissart bound and on the Equivalence Theorem. In this talk we briefly review some of our objections on the validity of such arguments. Some open questions are pointed out, in particular on the limit of zero mass for the vector mesons and on the fate of the longitudinal polarizations.

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Radiative corrections to W+W− → W+W− in the electroweak standard model

Cited by 69 publications

References 56 publications

NNLO computational techniques: The cases and

NNLO computational techniques: The cases and

Automatic calculations in high energy physics and GRACE at one-loop

Of higgs, unitarity and other questions

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