Searches for a New Gauge Boson at Different LEP Phases

Abstract

In this seminar, I will show that one of the several remarkable features of LEP would be that of allowing a search for the existence of one extra vector boson of extended gauge origin and mass up to a few hundred GeV in a very systematic and exhaustive way. This search would proceed in different steps, corresponding to three various phases of the machine that I will call phases 1, la and 2, respectively. They would roughly correspond to a first stage with total energy E ≲ 110 GeV and ∫L dt ≃ 100 pb⁻¹, an intermediate stage with either initial beam longitudinal polarization or very high luminosity (∼10⁸ Zs) available, and a final state with E_max ≃ 200 GeV, ∫L dt ≲ 500 pb⁻¹. Each of these phases would be able to reveal and to identify different signals of the new Z’ generated by independent parameters. Thus, a negative search at LEP would, at least, set limits on all the parameters of the involved models that would be, in general, competitive with those achievable in future pp, p̄ collider experiments.

On leave of absence from Department of Theoretical Physics, University of Trieste, and INFN, Sezione di Trieste, Italy