FUTURE V(TAU) OSCILLATION EXPERIMENTS AND PRESENT DATA

Our goal in this paper is to examine the discovery potential of labora tory experiments searching for the oscillation nu(mu)(nu(e)) --> nu(ta u), in the light of recent data on solar and atmospheric neutrino expe riments, which we analyse together with the most restrictive results f rom laboratory experiments on neutrino oscillations. In order to expla in simultaneously all present results we use a four-neutrino framework , with an additional sterile neutrino. Our predictions are rather pess imistic for the upcoming experiments NOMAD and CHORUS, which, we find, are able to explore only a small area of the oscillation parameter sp ace. On the other hand, the discovery potential of future experiments is much larger. We consider three examples. E803, which is approved to operate in the future Fermilab main injector beam line, MINOS, a prop osed long-baseline experiment also using the Fermilab beam, and NAUSIC AA, an improved detector which improves by an order of magnitude the p erformance of CHORUS/NOMAD and can be operated either at CERN or at Fe rmilab beams. We find that those experiments can cover a very substant ial fraction of the oscillation parameter space, having thus a very go od chance of discovering both nu(mu) --> nu(tau) and nu(e) --> nu(tau) oscillation modes.