SUSY virtual effects at the LEP2 boundary
M. Beccaria1,2 - P. Ciafaloni1,2 - D. Comelli3 - F. Renard4 - C. Verzegnassi1,2
1 Dipartimento di Fisica dell'Università di Lecce, I-73100, Italy
2 Istituto Nazionale di Fisica Nucleare, Sezione di Lecce, Lecce, Italy
3 Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, Ferrara, Italy
4 Physique Mathématique et Théorique, UMR 5825, Université Montpellier II, F-34095 Montpellier Cedex 5, France
Received: 19 March 1999 / Published online: 12 August 1999
We examine the possibility that SUSY particles are light, i.e. have a mass just beyond the final kinematical reach of LEP2. In this case, even if light particles are not directly detected, their virtual effects are enhanced by a "close-to-threshold'' resonance in the s-channel. We find that this resonant effect is absent in the case of light sfermions, while it is enhanced in the case of light gauginos, since neutralinos and charginos add coherently in some regions of the allowed parameter space. We discuss this "virtual alliance'' in detail and try to examine the possibilities of its experimental verification.