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Particles and Fields


Eur. Phys. J. C 20, 563-584 (2001)
DOI: 10.1007/s100520100679

Chargino and neutralino decays revisited

A. Djouadi1, Y. Mambrini1, 2 and M. Mühlleitner1

1  Laboratoire de Physique Mathématique et Théorique, UMR5825-CNRS, Université de Montpellier II, 34095 Montpellier Cedex 5, France
2  CEA/DIF/DPTA/SPN, B.P. 12, 91680 Bruyères le Châtel, France

(Received: 12 April 2001 / Published online: 8 June 2001 -© Springer-Verlag / Società Italiana di Fisica 2001)

Abstract
We perform a comprehensive analysis of the decays of charginos and neutralinos in the minimal supersymmetric standard model where the neutralino $\chi_1^0$ is assumed to be the lightest supersymmetric particle. We focus, in particular, on the three-body decays of the next-to-lightest neutralino and the lightest chargino into the lightest neutralino and fermion-antifermion pairs and include vector boson, Higgs boson and sfermion exchange diagrams, where in the latter contribution the full mixing in the third generation is included. The radiative corrections to the heavy fermion and SUSY particle masses will also be taken into account. We present complete analytical formulae for the Dalitz densities and the integrated partial decay widths in the massless fermion case, as well as the expressions of the differential decay widths including the masses of the final fermions and the polarization of the decaying charginos and neutralinos. We then discuss these decay modes, in particular in scenarios where the parameter $\tan \beta$ is large and in models without universal gaugino masses at the grand unification scale, where some new decay channels, such as decays into gluinos and $q\bar{q}$ pairs, open up.



© Società Italiana di Fisica, Springer-Verlag 2001