Light-gluino scenario

We investigate in detail the consequences of the supersymmetry scenario with a light (∼5 GeV) gluino and heavy (∼100 GeV) scalar quarks, including gluino distribution and fragmentation effects, proposed to explain large-missing-$p_T$ events observed at the CERN pp¯ collider. The effective gluino distribution in the nucleon is evaluated using the Altarelli-Parisi equations. Ambiguities in evaluating scalar-quark production with the effective gluino distribution are discussed. A plausible gluino fragmentation function is deduced from heavy-quark fragmentation functions; scaling violations in the gluino fragmentation function are taken into account. Fragmentation effects drastically reduce the missing $p_T$ in light-gluino jets. The present collider data do not rule out a light gluino with mass in the range of 3–5 GeV even if the g̃ lifetime, from decay into a photino and a quark pair, is short.