Zobrazeno 1 - 10
of 368
pro vyhledávání: '"Kleiss, R."'
The Landau-Yang theorem, forbidding transition amplitudes between a massive spin-1 particle and two photons, is widely assumed to apply to other massless spin-1 particles. We show that this is not true in Standard-Model QCD, so that for instance anti
Externí odkaz:
http://arxiv.org/abs/1508.07115
In Monte Carlo integration an accurate and reliable determination of the numerical intregration error is essential. We point out the need for an independent estimate of the error on this error, for which we present an unbiased estimator. In contrast
Externí odkaz:
http://arxiv.org/abs/1507.05031
Publikováno v:
Eur.Phys.J.C65:303-310,2010
The reality and convexity of the effective potential in quantum field theories has been studied extensively in the context of Euclidean space-time. It has been shown that canonical and path-integral approaches may yield different results, thus resolv
Externí odkaz:
http://arxiv.org/abs/0907.1174
Publikováno v:
Eur.Phys.J.C64:387-389,2009
We point out that the compact Feynman rules for Majorana fermions proposed by Denner et al. are in fact a convention for the complex phases of (anti)spinors, valid for both Majorana and Dirac fermions. We establish the relation of this phase conventi
Externí odkaz:
http://arxiv.org/abs/0906.3388
Autor:
Kleiss, R., Oord, G. van den
A recursive computation of scattering amplitudes including Majorana fermions requires a consistent definition of the fermion flow, which is introduced by Denner et al. in a diagrammatic setting. A systematic treatment in the off-shell current formali
Externí odkaz:
http://arxiv.org/abs/0906.0697
Publikováno v:
Eur.Phys.J.C64:319-349,2009
In QFT the effective potential is an important tool to study symmetry breaking phenomena. It is known that, in some theories, the canonical approach and the path-integral approach yield different effective potentials. In this paper we investigate thi
Externí odkaz:
http://arxiv.org/abs/0901.3700
Publikováno v:
Eur.Phys.J.C61:495-518,2009
We show how to transform a $d$-dimensional Euclidean path integral in terms of two (Cartesian) fields to a path integral in terms of polar field variables. First we present a conjecture that states how this transformation should be done. Then we show
Externí odkaz:
http://arxiv.org/abs/0901.0815
The usefulness of recursive equations to compute scattering matrix elements for arbitrary processes is discussed. Explicit results at tree and one-loop order, obtained by the HELAC/PHEGAS package that is based on the Dyson-Schwinger recursive equatio
Externí odkaz:
http://arxiv.org/abs/hep-ph/0607034
We perform an explicit computation of the effective action for a few zero-dimensional Euclidean field theories in which the bare action exhibits several (or infinitely many) minima. In all cases the effective action is well-defined for all field valu
Externí odkaz:
http://arxiv.org/abs/hep-ph/0509142
Autor:
Kleiss, R. H., Lazopoulos, A.
Publikováno v:
Comput.Phys.Commun. 175 (2006) 93-115
While the Quasi-Monte Carlo method of numerical integration achieves smaller integration error than standard Monte Carlo, its use in particle physics phenomenology has been hindered by the abscence of a reliable way to estimate that error. The standa
Externí odkaz:
http://arxiv.org/abs/hep-ph/0504085