اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدFirst evidence for the decay Bs -> mu+ mu-
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A search for the rare decays Bs->mu+mu- and B0->mu+mu- is performed using data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1 fb^-1 of proton-proton collisions at sqrt{s} = 8 TeV and 1.0 fb^-1 at sqrt{s}=7 TeV. We observe an excess of Bs -> mu+ mu- candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3 x 10^-4 corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of BR(Bs -> mu+ mu-) = (3.2^{+1.5}_{-1.2}) x 10^-9, where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the Standard Model expectation. The observed number of B0 -> mu+ mu- candidates is consistent with the background expectation, giving an upper limit of BR(B0 -> mu+ mu-) < 9.4 x 10^-10 at 95% confidence level.
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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. T
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A search for the decays Bs -> mu+ mu- and B0 -> mu+ mu- is performed with 0.37 fb^-1 of pp collisions at sqrt{s} = 7 TeV collected by the LHCb experiment in 2011. The upper limits on the branching fractions are BR (Bs -> mu+ mu-) < 1.6 x 10^-8 and BR
(B0 -> mu+ mu-) < 3.6 x 10^-9 at 95% confidence level. A combination of these results with the LHCb limits obtained with the 2010 dataset leads to BR (Bs -> mu+ mu-) < 1.4 x 10^-8 and BR (B0 -> mu+ mu-) < 3.2 x 10^-9 at 95% confidence level.
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 e
vents 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 Bs -> mu+ mu- and B0 -> mu+ mu- decays is performed using 1.0 fb^-1 of pp collision data collected at sqrt{s}=7 TeV with the LHCb experiment at the Large Hadron Collider. For both decays the number of observed events is consistent with e
xpectation from background and Standard Model signal predictions. Upper limits on the branching fractions are determined to be BR(Bs -> mu+ mu-) < 4.5 (3.8) x 10^-9 and BR(B0 -> mu+ mu-) < 1.0 (0.81) x 10^-9 at 95% (90%) confidence level.
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 e
vents 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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