Park, H.K.Burnstein, R.A.Chakravorty, A.Chen, Y.C.Choong, W.S.Clark, K.Dukes, E.C.Durandet, C.Felix, J.Fu, Y.Gidal, G.Gustafson, H.R.Holmstrom, T.Huang, M.James, C.Jenkins, C.M.Jones, T.Kaplan, D.M.Lederman, L.M.Leros, N.Longo, M.J.Lopez, F.Lu, L.C.Luebke, W.Luk, K.B.Nelson, K.S.Perroud, J.-P.Rajaram, D.Rubin, H.A.Volk, J.White, C.G.White, S.L.Zyla, P.2010-11-052010-11-052010-11-05200510.1103/PhysRevLett.94.0218012-s2.0-18144414341https://infoscience.epfl.ch/handle/20.500.14299/56828We report the first evidence for the decay ∑+ → pμ+ μ- from data taken by the HyperCP (E871) experiment at Fermilab. Based on three observed events, the branching ratio is B(∑+ → pμ+ μ-) = [8.6 -5.4 +6.6(stat) ± 5.5(syst)] × 10 -8. The narrow range of dimuon masses may indicate that the decay proceeds via a neutral intermediate state, ∑+ rarr; pp0, p0 → μ+ μ- with a P0 mass of 214.3 ± 0.5 MeV/c 2 and branching ratio B(∑+ rarr; pp 0, p0 → μ+ μ-) = [3.1-1.9 -2.4(stat) ± 1.5(syst)] × 10 -8. © 2005 The American Physical Society.text::journal::journal article::research article