Search for light gluinos via the spontaneous appearance of π⁺ π⁻ Pairs with an 800 GeV/c proton beam at fermilab

We searched for the appearance of π⁺ π⁻ pairs with invariant mass ≥ 648 MeV/c² in a neutral beam. Such an observation could signify the decay of a long-lived light neutral particle. We find no evidence for this decay. Our null result severely constrains the existence of an R⁰ hadron, which is the lightest bound state of a gluon and a light gluino (g^∼g), and thereby also the existence of a light gluino. Depending on the photino mass, we exclude the R⁰ in the mass and lifetime ranges of 1.2 − 4.6 GeV/c² and 2 × 10⁻⁷ × 10⁻⁴s, respectively.