11 research outputs found
Observation of the suppressed ADS modes B± â[ϱKâÏ+Ï-] D K± and B± â[ϱKâÏ+Ï-] Dϱ
An analysis of B± â DK± and B± â Dϱ decays is presented where the D meson is reconstructed in the four-body nal state K±ÏâÏ+Ï-. Using LHCb data corresponding to an integrated luminosity of 1.0 fb-1, rst observations are made of the suppressed ADS modes B± â[ϱKâÏ+Ï-] D K± and B± â [ϱKâÏ+Ï-]Dϱ with a signicance of 5.1Ï and greater than 10Ï, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured B± â DK± amplitudes is determined to be rK B = 0.097±0.011. © CERN for the benet of the LHCb Collaboration
LHCb detector performance
The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are described, using data taken from 2010 to 2012. It is shown that the design criteria of the experiment have been met. The excellent performance of the detector has allowed the LHCb collaboration to publish a wide range of physics results, demonstrating LHCb's unique role, both as a heavy flavour experiment and as a general purpose detector in the forward region
Observation of the suppressed ADS modes B± â[ϱKâÏ+Ï-] D K± and B± â[ϱKâÏ+Ï-] Dϱ
An analysis of B± â DK± and B± â Dϱ decays is presented where the D meson is reconstructed in the four-body nal state K±ÏâÏ+Ï-. Using LHCb data corresponding to an integrated luminosity of 1.0 fb-1, rst observations are made of the suppressed ADS modes B± â[ϱKâÏ+Ï-] D K± and B± â [ϱKâÏ+Ï-]Dϱ with a signicance of 5.1Ï and greater than 10Ï, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured B± â DK± amplitudes is determined to be rK B = 0.097±0.011. © CERN for the benet of the LHCb Collaboration
Measurement of the B ± production cross-section in pp collisions at âs = 7 TeV
The production of B ± mesons in proton-proton collisions at âs = 7TeVis studied using 35 pb -1 of data collected by the LHCb detector. The B ± mesons are reconstructed exclusively in the B ± â J/ΚK ± mode, with J/ΚâÎŒ +ÎŒ -. The differential production cross-section is measured as a function of the B ± transverse momentum in the ducial region 0 < pT < 40 GeV=c and with rapidity 2:0 < y < 4:5. The total cross-section, summing up B + and B -, is measured to be Ï(pp â B ±X; 0 < pT < 40 GeV=c; 2:0 < y < 4:5) = 41:4 ± 1:5 (stat:) ± 3:1 (syst:) ÎŒb. Copyright CERN
Measurement of CP violation in the B-s(0)-> phi phi decay and search for the B-0 -> phi phi decay
A measurement of the time-dependent CP-violating asymmetry in B0sâÏÏ decays is presented. Using a sample of proton-proton collision data corresponding to an integrated luminosity of 5.0 fbâ1 collected by the LHCb experiment at centre-of-mass energies sâ = 7 TeV in 2011, 8 TeV in 2012 and 13 TeV in 2015 and 2016, a signal yield of around 9000 B0sâÏÏ decays is obtained. The CP-violating phase ÏssÂŻÂŻÂŻss is measured to be â0.073 ± 0.115(stat) ± 0.027(syst) rad, under the assumption it is independent of the helicity of the ÏÏ decay. In addition, the CP-violating phases of the transverse polarisations under the assumption of CP conservation of the longitudinal phase are measured. The helicity-independent direct CP-violation parameter is also measured, and is found to be |λ| = 0.99 ± 0.05(stat) ± 0.01(syst). In addition, T-odd triple-product asymmetries are measured. The results obtained are consistent with the hypothesis of CP conservation in bÂŻÂŻâsÂŻÂŻÂŻssÂŻÂŻÂŻs transitions. Finally, a limit on the branching fraction of the B0 â ÏÏ decay is determined to be B(B0âÏÏ)<2.7Ă10â8 at 90 % confidence level