arXiv subjects

E. Chopin

Publications and source records attributed to E. Chopin.

3 recordsLinked to original sources

arXiv1998

Improvement of the Calculation of Scattering Amplitudes with External Fermions

In this paper, we present an improvement of a method for computing scattering amplitudes that include external (polarized) fermions with the following features: the formulas are quite general and work for different kinematic configurations and different external masses, they are explicitly covariant, they do not depend on a specific representation of the Dirac matrices and they have a meaningful limit when the masses tend to 0. The results presented make use of some well known formulas describing the density matrices in terms of projection operators within a more general formalism. Since our formulas intend to be as general as possible, we also take into account the possibility of a transverse polarization for massless fermions.

hep-ph↗

arXiv1996

New Physics with three-photon events at LEP

The effect of the most general \z3gt vertex in the reaction $e^+e^- \ra 3γ$ is studied with a particular attention to LEP searches. We give exact analytical expressions including realistic cuts for the signal and present a detailed analysis based on a Monte Carlo that includes the effect of the irreducible $3γ$ QED cross section. As special applications we discuss the effect of heavy scalars, fermions and gauge bosons and comment on the ``monopole" connection.

hep-ph↗

arXiv1995

Double Higgs Production at the Linear Colliders and the Probing of the Higgs Self-Coupling

We study double Higgs production in the $e^+ e^-$ and $γγ$ modes of the linear collider. It is also shown how one can probe the scalar potential in these reactions. We discuss the effective longitudinal $W$ approximation in $γγ$ processes and the $W_L W_L$ luminosities in the two modes of a high-energy linear collider. A generalised non-linear gauge-fixing condition, which is particularly useful for tree-level calculations of electroweak processes for the laser induced collider, is presented. Its connection with the background-field approach to gauge fixing is given.

hep-ph↗