Search for Light Gluinos via the Spontaneous Appearance of pi+pi- Pairs with an 800 GeV/c Proton Beam at Fermilab

TL;DR

This study searched for signs of light gluinos by detecting pi+pi- pairs in high-energy proton beam experiments, but found no evidence, thus constraining the existence of certain hypothesized particles.

Contribution

It provides the first experimental constraints on the existence of light gluinos and R0 hadrons in specific mass and lifetime ranges.

Findings

No evidence for R0 decay observed.

Excludes R0 in mass range 1.2-4.6 GeV for certain lifetimes.

Severely constrains light gluino models.

Abstract

We searched for the appearance of pi+pi- pairs with invariant mass greater than 648 MeV 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, and thereby also the possibility 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 and 2E-10 -- 7E-4 seconds, respectively. (To Appear in Phys. Rev. Lett.)