Search for light top squarks in pp̄ collisions at √s = 1.8 TeV

We present a search for pair produced top squarks, the supersymmetric partners of the top quark, using the D0 detector at the Fermilab Tevatronpp collider. We consider a scenario in which the lighter of the two top squarks t 1 decays with 100% branching fractionto a charm quarkand the lightest neutralinoχ 1 0 yielding a signal of two acollinear jets with missing transverse energy. We observe 3 events while we expect 3.5±1.2 events from the known standard model processes. We excludeat the 95% confidence level a significant region of the m t 1 - m χ 1 0 parameter space. The highest m t 1 value we excludeis 93 GeV/c 2 with a corresponding m χ 1 0 value of 8 GeV/c 2 .