8 research outputs found
Measurement of the flavour-specific CP-violating asymmetry as sl in B0s decays
The CP  -violating asymmetry is studied using semileptonic decays of and mesons produced in pp  collisions at a centre-of-mass energy of 7 TeV at the LHC, exploiting a data sample corresponding to an integrated luminosity of 1.0 fbâ1. The reconstructed final states are , with the particle decaying in the Ïϱ mode. The yields are summed over and initial states, and integrated with respect to decay time. Data-driven methods are used to measure efficiency ratios. We obtain , where the first uncertainty is statistical and the second systematic
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
Measurement of the time-dependent CP asymmetry in B0 -> J/Ï KS0 decays
This Letter reports a measurement of the CP violation observables SJ/ÏK0S and CJ/ÏK0S in the decay channel B0âJ/ÏK0S performed with 1.0 fbâ1 of pp collisions at sâ=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ÏK0S=0.73±0.07(stat)±0.04(syst) and CJ/ÏK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
Determining the jet transport coefficient qÌ from inclusive hadron suppression measurements using Bayesian parameter estimation
We report a new determination of Ëq, the jet transport coefficient of the quark-gluon plasma. We use the JETSCAPE framework, which incorporates a novel multistage theoretical approach to in-medium jet evolution and Bayesian inference for parameter extraction. The calculations, based on the Matter and Lbt jet quenching models, are compared to experimental measurements of inclusive hadron suppression in Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and Pb+Pb collisions at the CERN Large Hadron Collider (LHC). The correlation of experimental systematic uncertainties is accounted for in the parameter extraction. The functional dependence of Ëq on jet energy or virtuality and medium temperature is based on a perturbative picture of in-medium scattering, with components reflecting the different regimes of applicability of Matter and Lbt. In the multistage approach, the switch between Matter and Lbt is governed by a virtuality scale Q0. Comparison of the posterior model predictions to the RHIC and LHC hadron suppression data shows reasonable agreement, with moderate tension in limited regions of phase space. The distribution of Ëq/T3 extracted from the posterior distributions exhibits weak dependence on jet momentum and medium temperature T, with 90% credible region (CR) depending on the specific choice of model configuration. The choice of Matter+Lbt, with switching at virtuality Q0, has 90% CR of 240 GeV/c. The value of Q0, determined here for the first time, is in the range 2.0â2.7 GeV
Observation of B[0s Ïc1Ï decay and study of: B0 -> Ï c1,2K*1 decays
The first observation of the decay B0s â Ïc1Ï and a study of B0 â Ïc1,2K*0 decays are presented. The analysis is performed using a dataset, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. The following ratios of branching fractions are measured: Where the third uncertainty is due to the limited knowledge of the branching fractions of Ïc â J/ÏÎł modes. © 2013 CERN. Published by Elsevier B.V
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