Evidence for the DecayΣ+→pμ+μ−

Abstract

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).

Σb→ΣcandΩb→Ωcweak decays in the light-front quark model

“…For example, as the decay AE ! p þ À was observed [2], the authors of Refs. [3,4] studied the contribution from new physics candidates by analyzing the data.…”

Exotic decays of the 125 GeV Higgs boson

“…A collider search for h → 2a → 4μ was first proposed in [380], which took m a ≈ 215 MeV, as motivated by an excess in HyperCP measurements of Σ þ → pμ þ μ − decay [381]. This study pointed out that modifications of the (then-)standard muon isolation algorithms would be required to preserve the signal and concluded that as long as reasonable efficiencies for muon identification could be maintained, the signal had excellent prospects for detection.…”

Decay rate and asymmetries of Σ+ → pμ+μ−

“…The quantities pertinent to Σ + → pµ + µ − that have been measured so far are the branching fraction and the dimuon invariant-mass distribution [1,2]. If a good amount of data on this decay become available from future experimental efforts, there are other observables that can be analyzed.…”

“…The rare hyperon decay Σ + → pµ + µ − gained much attention in 2005 when the HyperCP Collaboration at Fermilab reported the first evidence for this mode consisting of three events with the same dimuon invariant mass M µµ = 214.3 MeV [1]. Although the implied rate was consistent with its standard model (SM) value, the event clustering hinted at the possibility that the decay was mediated by a light new particle.…”