We report the first evidence for the decay Sigma(+)-->pmu(+)mu(-) from data taken by the HyperCP (E871) experiment at Fermilab. Based on three observed events, the branching ratio is B(Sigma(+)-->pmu(+)mu(-))=[8.6(+6.6)(-5.4)(stat)+/-5.5(syst)]x10(-8). The narrow range of dimuon masses may indicate that the decay proceeds via a neutral intermediate state, Sigma(+)-->pP(0),P0-->mu(+)mu(-) with a P0 mass of 214.3+/-0.5 MeV/c(2) and branching ratio B(Sigma(+)-->pP(0),P0-->mu(+)mu(-))=[3.1(+2.4)(-1.9)(stat)+/-1.5(syst)]x10(-8).

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The fixed-target Main Injector Particle Production (MIPP) experiment, Fermilab E907, was designed to measure the production of hadrons from the collisions of hadrons of momenta ranging from 5 to 120 GeV=c on a variety of nuclei. These data will generally improve the simulation of particle detectors and predictions of particle beam fluxes at accelerators. The spectrometer momentum resolution is between 3% and 4%, and particle identification is performed for particles ranging between 0.3 and 80 GeV=c using dE=dx, time-of-flight, and Cherenkov radiation measurements. MIPP collected 1.42 × 10 6 events of 120 GeV Main Injector protons striking a target used in the Neutrinos at the Main Injector facility at Fermilab. The data have been analyzed and we present here charged pion yields per proton on target determined in bins of longitudinal and transverse momentum between 0.5 and 80 GeV=c, with combined statistical and systematic relative uncertainties between 5% and 10%.