143 research outputs found
Measurement of CP observables in B± â D(â)K± and B± â D(â)ϱ decays
Measurements of CP observables in B ± âD (â) K ± and B ± âD (â) Ï Â± decays are presented, where D (â) indicates a neutral D or D â meson that is an admixture of D (â)0 and DÂŻ (â)0 states. Decays of the D â meson to the DÏ 0 and DÎł final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the B candidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K ± Ï â , K + K â and Ï + Ï â final states. The analysis uses a sample of charged B mesons produced in pp collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb â1 taken at centre-of-mass energies of s=7, 8 and 13 TeV, respectively. The study of B ± âD â K ± and B ± âD â Ï Â± decays using a partial reconstruction method is the first of its kind, while the measurement of B ± âDK ± and B ± âDÏ Â± decays is an update of previous LHCb measurements. The B ± âDK ± results are the most precise to date
Measurement of the Î<sup>-</sup><sub>b</sub> and Ω<sup>-</sup><sub>b</sub> baryon lifetimes
Using a data sample of pp collisions corresponding to an integrated luminosity of , the and baryons are reconstructed in the and decay modes and their lifetimes measured to be \tau (\Xi_b^-) = 1.55\, ^{+0.10}_{-0.09}~{\rm(stat)} \pm 0.03\,{\rm(syst)} ps, \tau (\Omega_b^-) = 1.54\, ^{+0.26}_{-0.21}~{\rm(stat)} \pm 0.05\,{\rm(syst)} ps. These are the most precise determinations to date. Both measurements are in good agreement with previous experimental results and with theoretical predictions
First observation and amplitude analysis of the BââD+KâÏâ decay
The BââD+KâÏâ decay is observed in a data sample corresponding to 3.0ââfbâ1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. Its branching fraction is measured to be B(BââD+KâÏâ)=(7.31±0.19±0.22±0.39)Ă10â5 where the uncertainties are statistical, systematic and from the branching fraction of the normalization channel BââD+ÏâÏâ, respectively. An amplitude analysis of the resonant structure of the BââD+KâÏâ decay is used to measure the contributions from quasi-two-body BââDâ0(2400)0Kâ, BââDâ2(2460)0Kâ, and BââDâJ(2760)0Kâ decays, as well as from nonresonant sources. The DâJ(2760)0 resonance is determined to have spin 1
First observation and amplitude analysis of the B- -> D+K-pi(-) decay
The B-âD+K-Ï- decay is observed in a data sample corresponding to 3.0 fb-1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. Its branching fraction is measured to be B(B-âD+K-Ï-)=(7.31±0.19±0.22±0.39)Ă10-5 where the uncertainties are statistical, systematic and from the branching fraction of the normalization channel B-âD+Ï-Ï-, respectively. An amplitude analysis of the resonant structure of the B-âD+K-Ï- decay is used to measure the contributions from quasi-two-body B-âD0â(2400)0K-, B-âD2â(2460)0K-, and B-âDJâ(2760)0K- decays, as well as from nonresonant sources. The DJâ(2760)0 resonance is determined to have spin 1
Measurement of the Difference of Time-Integrated CPAsymmetries in D0âKâK+ and D0âÏâÏ+ Decays
A search for CP violation in and decays is performed using collision data,
corresponding to an integrated luminosity of , collected using the
LHCb detector at centre-of-mass energies of 7 and TeV. The flavour of the
charm meson is inferred from the charge of the pion in and decays. The difference
between the CP asymmetries in and decays, , is measured to be . This is the most precise measurement of a
time-integrated CP asymmetry in the charm sector from a single experiment.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-055.htm
Dalitz plot analysis ofB0âDÂŻ0Ï+Ïâdecays
The resonant substructures of decays are
studied with the Dalitz plot technique. In this study a data sample
corresponding to an integrated luminosity of 3.0 fb of collisions
collected by the LHCb detector is used. The branching fraction of the decay in the region
GeV is measured to be ,
where the first uncertainty is statistical, the second is systematic and the
last arises from the normalisation channel . The
S-wave components are modelled with the Isobar and K-matrix
formalisms. Results of the Dalitz plot analyses using both models are
presented. A resonant structure at
GeV is confirmed and its spin-parity is determined for the first time
as . The branching fraction, mass and width of this structure are
determined together with those of the and
resonances. The branching fractions of other decay
components with are also reported. Many of these branching
fraction measurements are the most precise to date. The first observation of
the decays , , ,
and the first evidence of are presented.Comment: 64 pages, 17 figure
Study of D-(*())(+)(sJ) mesons decaying to D*K-+(S)0 and D*K-0(+) final states
A search is performed for mesons in the reactions and using data collected at
centre-of-mass energies of 7 and 8 TeV with the LHCb detector. For the final state, the decays with and are used. For , the
decay with is used. A prominent
signal is observed in both and final states. The resonances and are
also observed, yielding information on their properties, including spin-parity
assignments. The decay is observed
for the first time, at a significance of 6.9 , and its branching
fraction relative to the decay mode is
measured
Search for Violations of Lorentz Invariance and CPT Symmetry in B-(s)(0) Mixing
Violations of CPT symmetry and Lorentz invariance are searched for by studying interference effects in B^{0} mixing and in B_{s}^{0} mixing. Samples of B^{0}âJ/ÏK_{S}^{0} and B_{s}^{0}âJ/ÏK^{+}K^{-} decays are recorded by the LHCb detector in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3ââfb^{-1}. No periodic variations of the particle-antiparticle mass differences are found, consistent with Lorentz invariance and CPT symmetry. Results are expressed in terms of the standard model extension parameter Îa_{ÎŒ} with precisions of O(10^{-15}) and O(10^{-14})ââGeV for the B^{0} and B_{s}^{0} systems, respectively. With no assumption on Lorentz (non)invariance, the CPT-violating parameter z in the B_{s}^{0} system is measured for the first time and found to be Re(z)=-0.022±0.033±0.005 and Im(z)=0.004±0.011±0.002, where the first uncertainties are statistical and the second systematic
Measurement of , , and production asymmetries in 7 and 8 TeV proton-proton collisions
See paper for full list of authors - All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-062.html - Submitted to Phys. Lett. B.International audienceThe B0, B0s, B+ and Î0b hadron production asymmetries are measured using a data sample corresponding to an integrated luminosity of 3.0 fbâ1, collected by the LHCb experiment in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. The measurements are performed as a function of transverse momentum and rapidity of the b hadrons within the LHCb detector acceptance. The overall production asymmetries, integrated over transverse momentum and rapidity, are also determined
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