4 research outputs found
Searches for violation of lepton flavour and baryon number in tau lepton decays at LHCb
Searches for the lepton flavour violating decay ÏââÎŒâÎŒ+ÎŒâÏââÎŒâÎŒ+ÎŒâ and the lepton flavour and baryon number violating decays sourceÏââpÂŻÎŒ+ÎŒâ and ÏââpÎŒâÎŒâÏââpÎŒâÎŒâ have been carried out using protonâproton collision data, corresponding to an integrated luminosity of 1.0 fbâ11.0 fbâ1, taken by the LHCb experiment at s=7 TeV. No evidence has been found for any signal, and limits have been set at 90%90% confidence level on the branching fractions: B(ÏââÎŒâÎŒ+ÎŒâ)<8.0Ă10â8B(ÏââÎŒâÎŒ+ÎŒâ)<8.0Ă10â8, B(ÏââpÂŻÎŒ+ÎŒâ)<3.3Ă10â7 and B(ÏââpÎŒâÎŒâ)<4.4Ă10â7B(ÏââpÎŒâÎŒâ)<4.4Ă10â7. The results for the ÏââpÂŻÎŒ+ÎŒâ and ÏââpÎŒâÎŒâÏââpÎŒâÎŒâ decay modes represent the first direct experimental limits on these channels
Search for the rare decay
22 pages, 8 figures, Submitted to Physics Letters BA search for the rare decay is performed using a data sample, corresponding to an integrated luminosity of 0.9 fb, of collisions collected at a centre-of-mass energy of 7 TeV by the LHCb experiment. The observed number of events is consistent with the background expectations and corresponds to an upper limit of \mbox{} at \mbox{90%} \mbox{(95%)} confidence level. This result represents an improvement of more than a factor twenty with respect to previous measurements
Search for D+(s) to pi+ mu+ mu- and D+(s) to pi- mu+ mu+ decays
21 pages, 5 figures - See paper for full list of authorsA search for non-resonant D+(s) to pi+mu+mu- and D+(s) to pi-mu+mu+ decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb-1, at sqrt(s) = 7 TeV recorded by the LHCb experiment in 2011. No signals are observed and the 90% (95%) confidence level (CL) limits on the branching fractions are B(D+ to pi+mu+mu-) < 7.3 (8.3) x 10-8, B(Ds+ to pi+mu+mu-) < 4.1 (4.8) x 10-7, B(D+ to pi-mu+mu+) < 2.2 (2.5) x 10-8, B(Ds+ to pi-mu+mu+) < 1.2 (1.4) x 10-7. These limits are the most stringent to date
Search for direct CP violation in D0 -> h- h+ modes using semileptonic B decays
15 pages, 4 figures - See paper for full list of authorsA search for direct CP violation in D0 -> h- h+ (where h=K or pi) is presented using data corresponding to an integrated luminosity of 1.0 fb^-1 collected in 2011 by LHCb in pp collisions at a centre-of-mass energy of 7 TeV. The analysis uses D0 mesons produced in inclusive semileptonic b-hadron decays to the D0 mu X final state, where the charge of the accompanying muon is used to tag the flavour of the D0 meson. The difference in the CP-violating asymmetries between the two decay channels is measured to be Delta A_CP = A_CP(K-K+) - A_CP(pi-pi+) = (0.49 +- 0.30 (stat) +- 0.14 (syst)) % . This result does not confirm the evidence for direct CP violation in the charm sector reported in other analyses