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Register a new userEvidence for the rare decay $Sigma^+ to p mu^+ mu^-$ at LHCb
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Authors
Francesco Dettori
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A search for the rare decay $Sigma^+ to p mu^+ mu^-$ is performed using $pp$ collision data recorded by the LHCb experiment at centre-of-mass energies $sqrt{s} = 7$ and $8$ TeV, corresponding to an integrated luminosity of $3 fb^{-1}$. An excess of events is observed with respect to the background expectations with a signal significance of 4.0 standard deviations. No significant structure is observed in the dimuon invariant mass distribution.
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A search for the rare decay $Sigma^+ to p mu^+ mu^-$ is performed using $pp$ collision data recorded by the LHCb experiment at centre-of-mass energies $sqrt{s} = 7$ and $8$ TeV, corresponding to an integrated luminosity of $3 fb^{-1}$. An excess of events is observed with respect to the background expectation, with a signal significance of 4.1 standard deviations. No significant structure is observed in the dimuon invariant mass distribution, in contrast with a previous result from the HyperCP experiment. The measured $Sigma^+ to p mu^+ mu^-$ branching fraction is $(2.2,^{+,1.8}_{-,1.3})times 10^{-8}$, where statistical and systematic uncertainties are included, which is consistent with the Standard Model prediction.
A search for $Sigma^+ to p mu^+ mu^-$ decays with LHCb Run 1 data is presented, yielding an evidence for this decay and a measurement of a branching fraction compatible with the Standard Model. The HyperCP anomaly in the dimuon invariant mass distribution is not confirmed, and its branching fraction central value is excluded at 95% CL. Prospects for the future of this measurement in LHCb are also presented.
We report the first evidence for the decay Sigma+ -> p mu+ mu- from data taken by the HyperCP experiment(E871) at Fermilab. Based on three observed events, the branching ratio is B(Sigma+ -> p,mu+,mu-) = [8.6 +6.6,-5.4(stat) +/-5.5(syst)] x 10**-8. The narrow range of dimuon masses may indicate that the decay proceeds via a neutral intermediate state, Sigma+ -> p P0, P0 -> mu+ mu-, with a P0 mass of 214.3 +/- 0.5 MeV/c**2 and branching ratio B(Sigma+ -> p P0; P0 -> mu+ mu-) = [3.1 +2.4,-1.(stat) +/-1.5(syst)] x 10**-8.
A search for the decay KS -> mu+ mu- is performed, based on a data sample of 1.0 fb^-1 of pp collisions at sqrt{s}=7 TeV collected by the LHCb experiment at the Large Hadron Collider. The observed number of candidates is consistent with the background-only hypothesis, yielding an upper limit of BR(KS -> mu+ mu-) < 11 (9) x 10^-9 at 95 (90)% confidence level. This limit is a factor of thirty below the previous measurement.
A search for the rare leptonic decay $B^{+} rightarrow {mu}^{+}{mu}^{-}{mu}^{+}{ u}_{{mu}}$ is performed using proton-proton collision data corresponding to an integrated luminosity of $4.7$ fb$^{-1}$ collected by the LHCb experiment. The search is carried out in the region where the lowest of the two ${mu}^{+}{mu}^{-}$ mass combinations is below $980$MeV/c$^{2}$. The data are consistent with the background-only hypothesis and an upper limit of $1.6 times 10^{-8}$ at 95% confidence level is set on the branching fraction in the stated kinematic region.
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