SIGNALS OF A SUPERLIGHT GRAVITINO AT HADRON COLLIDERS WHEN THE OTHER SUPERPARTICLES ARE HEAVY

If the gravitino (G) over tilde is very light and all the other supers ymmetric particles are above threshold, supersymmetry may still be fou nd at colliders, by looking at processes with only gravitinos and ordi nary particles in the final state. We compute here the cross sections for some distinctive signals at hadron colliders: photon plus missing energy, induced by q (q) over bar --> (GG) over tilde gamma, and jet p lus missing energy, induced by q (q) over bar --> (GG) over tilde g, ( q) over bar g --> (GG) over tilde q, (q) over bar g --> (GG) over tild e (q) over bar and gg --> (GG) over tilde g. From the present Tevatron data, we estimate the bound m(3/2) > 2.7 X 10(-5) eV on the gravitino mass, corresponding to the bound root F > 335 GeV on the supersymmetr y-breaking scale. We foresee that the upgraded Tevatron and the LHC wi ll be sensitive to values of m(3/2) up to 4.9 x 10(-5) eV and 1.2 x 10 (-3) eV, corresponding to root F up to 450 GeV and 2.2 TeV, respective ly. (C) 1998 Elsevier Science B.V.