Eur. Phys. J. C 10, 499-513
G.J. Gounaris1 - J. Layssac2 - P.I. Porfyriadis1 - F.M. Renard2
1 Department of Theoretical Physics, Aristotle
University of Thessaloniki,
GR-54006, Thessaloniki, Greece
2 Physique Mathématique et Théorique, UMR 5825, Université Montpellier II, F-34095 Montpellier Cedex 5, France
Received: 26 April 1999 / Published online: 8 September 1999
We study the helicity amplitudes and the observables of the process at high energy. As in the case of the process studied before, the relevant diagrams in the standard model (SM) involve W, charged-quark, and lepton loops, while in SUSY we also have contributions from charginos and charged-sfermion or Higgs-loop diagrams. Above 250 GeV, the dominant SM amplitudes are themselves dominated by the W loop, and as for , they are helicity conserving and almost purely imaginary. We discuss the complementary information provided by for the identification of possible nonstandard effects. This process, together with , should provide very useful information on the nature of possible new physics particles, above the threshold of their direct production.