Using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb−1, recorded by the LHCb detector at center-of-mass energies of 7 and 8 TeV, the Bc+→D0K+ decay is observed with a statistical si...
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Using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb−1, recorded by the LHCb detector at center-of-mass energies of 7 and 8 TeV, the Bc+→D0K+ decay is observed with a statistical significance of 5.1 standard deviations. By normalizing to B+→D¯0π+ decays, a measurement of the branching fraction multiplied by the production rates for Bc+ relative to B+ mesons in the LHCb acceptance is obtained, RD0K=(fc/fu)×B(Bc+→D0K+)=(9.3−2.5+2.8±0.6)×10−7, where the first uncertainty is statistical and the second is systematic. This decay is expected to proceed predominantly through weak annihilation and penguin amplitudes, and is the first Bc+ decay of this nature to be observed.
The Ξc+K− mass spectrum is studied with a sample of pp collision data corresponding to an integrated luminosity of 3.3 fb−1, collected by the LHCb experiment. The Ξc+ is reconstructed in the decay mode pK−π+. Five...
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The Ξc+K− mass spectrum is studied with a sample of pp collision data corresponding to an integrated luminosity of 3.3 fb−1, collected by the LHCb experiment. The Ξc+ is reconstructed in the decay mode pK−π+. Five new, narrow excited Ωc0 states are observed: the Ωc(3000)0, Ωc(3050)0, Ωc(3066)0, Ωc(3090)0, and Ωc(3119)0. Measurements of their masses and widths are reported.
Asymmetries in the time-dependent rates of D0→K+K− and D0→π+π− decays are measured in a pp collision data sample collected with the LHCb detector during LHC Run 1, corresponding to an integrated luminosity of 3 f...
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Asymmetries in the time-dependent rates of D0→K+K− and D0→π+π− decays are measured in a pp collision data sample collected with the LHCb detector during LHC Run 1, corresponding to an integrated luminosity of 3 fb−1. The asymmetries in effective decay widths between D0 and D¯0 decays, sensitive to indirect CP violation, are measured to be AΓ(K+K−)=(−0.30±0.32±0.10)×10−3 and AΓ(π+π−)=(0.46±0.58±0.12)×10−3, where the first uncertainty is statistical and the second systematic. These measurements show no evidence for CP violation and improve on the precision of the previous best measurements by nearly a factor of two.
A search for the rare decays Bs0→τ+τ− and B0→τ+τ− is performed using proton–proton collision data collected with the LHCb detector. The data sample corresponds to an integrated luminosity of 3 fb−1 collected i...
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A search for the rare decays Bs0→τ+τ− and B0→τ+τ− is performed using proton–proton collision data collected with the LHCb detector. The data sample corresponds to an integrated luminosity of 3 fb−1 collected in 2011 and 2012. The τ leptons are reconstructed through the decay τ−→π−π+π−ντ. Assuming no contribution from B0→τ+τ− decays, an upper limit is set on the branching fraction B(Bs0→τ+τ−)<6.8×10−3 at the 95% confidence level. If instead no contribution from Bs0→τ+τ− decays is assumed, the limit is B(B0→τ+τ−)<2.1×10−3 at the 95% confidence level. These results correspond to the first direct limit on B(Bs0→τ+τ−) and the world’s best limit on B(B0→τ+τ−).
We report the first observation of a baryonic Bs0 decay, Bs0→pΛ¯K−, using proton-proton collision data recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated l...
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We report the first observation of a baryonic Bs0 decay, Bs0→pΛ¯K−, using proton-proton collision data recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0 fb−1. The branching fraction is measured to be B(Bs0→pΛ¯K−)+B(Bs0→p¯ΛK+)=[5.46±0.61±0.57±0.50(B)±0.32(fs/fd)]×10−6, where the first uncertainty is statistical and the second systematic, the third uncertainty accounts for the experimental uncertainty on the branching fraction of the B0→pΛ¯π− decay used for normalization, and the fourth uncertainty relates to the knowledge of the ratio of b-quark hadronization probabilities fs/fd.
The first observation of the decays Λb0→χc1pK− and Λb0→χc2pK− is reported using a data sample corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment in pp collisions at center-o...
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The first observation of the decays Λb0→χc1pK− and Λb0→χc2pK− is reported using a data sample corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment in pp collisions at center-of-mass energies of 7 and 8 TeV. The following ratios of branching fractions are measured: B(Λb0→χc1pK−)B(Λb0→J/ψpK−)=0.242±0.014±0.013±0.009,B(Λb0→χc2pK−)B(Λb0→J/ψpK−)=0.248±0.020±0.014±0.009,B(Λb0→χc2pK−)B(Λb0→χc1pK−)=1.02±0.10±0.02±0.05,where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty on the branching fractions of the χc1→J/ψγ and χc2→J/ψγ decays. Using both decay modes, the mass of the Λb0 baryon is also measured to be mΛb0=5619.44±0.28±0.26 MeV/c2, where the first and second uncertainties are statistical and systematic, respectively.
A highly significant structure is observed in the Λc+K−π+π+ mass spectrum, where the Λc+ baryon is reconstructed in the decay mode pK−π+. The structure is consistent with originating from a weakly decaying partic...
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A highly significant structure is observed in the Λc+K−π+π+ mass spectrum, where the Λc+ baryon is reconstructed in the decay mode pK−π+. The structure is consistent with originating from a weakly decaying particle, identified as the doubly charmed baryon Ξcc++. The difference between the masses of the Ξcc++ and Λc+ states is measured to be 1334.94±0.72(stat.)±0.27(syst.) MeV/c2, and the Ξcc++ mass is then determined to be 3621.40±0.72(stat.)±0.27(syst.)±0.14(Λc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Λc+ mass. The state is observed in a sample of proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb−1, and confirmed in an additional sample of data collected at 8 TeV.
The first full amplitude analysis of B+→J/ψϕK+ with J/ψ→μ+μ−, ϕ→K+K− decays is performed with a data sample of 3 fb−1 of pp collision data collected at s=7 and 8 TeV with the LHCb detector. The data cannot be ...
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The first full amplitude analysis of B+→J/ψϕK+ with J/ψ→μ+μ−, ϕ→K+K− decays is performed with a data sample of 3 fb−1 of pp collision data collected at s=7 and 8 TeV with the LHCb detector. The data cannot be described by a model that contains only excited kaon states decaying into ϕK+, and four J/ψϕ structures are observed, each with significance over 5 standard deviations. The quantum numbers of these structures are determined with significance of at least 4 standard deviations. The lightest has mass consistent with, but width much larger than, previous measurements of the claimed X(4140) state.
The first observation of the decay of a B0 meson to a purely baryonic final state, B0→pp¯, is reported. The proton-proton collision data sample used was collected with the LHCb experiment at center-of-mass energ...
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The first observation of the decay of a B0 meson to a purely baryonic final state, B0→pp¯, is reported. The proton-proton collision data sample used was collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3.0 fb−1. The branching fraction is determined to be B(B0→pp¯)=(1.25±0.27±0.18)×10−8, where the first uncertainty is statistical and the second systematic. The decay mode B0→pp¯ is the rarest decay of the B0 meson observed to date. The decay Bs0→pp¯ is also investigated. No signal is seen and the upper limit B(Bs0→pp¯)<1.5×10−8 at 90% confidence level is set on the branching fraction.
A search for the rare decays Bs0→μ+μ− and B0→μ+μ− is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb−1. An excess of Bs0→μ+μ− d...
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A search for the rare decays Bs0→μ+μ− and B0→μ+μ− is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb−1. An excess of Bs0→μ+μ− decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(Bs0→μ+μ−)=(3.0±0.6−0.2+0.3)×10−9, where the first uncertainty is statistical and the second systematic. The first measurement of the Bs0→μ+μ− effective lifetime, τ(Bs0→μ+μ−)=2.04±0.44±0.05 ps, is reported. No significant excess of B0→μ+μ− decays is found, and a 95% confidence level upper limit, B(B0→μ+μ−)<3.4×10−10, is determined. All results are in agreement with the standard model expectations.
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