A search for baryon-number violating Ξb0 oscillations is performed with a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 3 fb−1. The baryon number at the mo...
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A search for baryon-number violating Ξb0 oscillations is performed with a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 3 fb−1. The baryon number at the moment of production is identified by requiring that the Ξb0 come from the decay of a resonance Ξb*−→Ξb0π− or Ξb′−→Ξb0π−, and the baryon number at the moment of decay is identified from the final state using the decays Ξb0→Ξc+π−,Ξc+→pK−π+. No evidence of baryon-number violation is found, and an upper limit at the 95% confidence level is set on the oscillation rate of ω<0.08 ps−1, where ω is the associated angular frequency.
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 decays χc1→J/ψμ+μ− and χc2→J/ψμ+μ− are observed and used to study the resonance parameters of the χc1 and χc2 mesons. The masses of these states are measured to be m(χc1)=3510.71±0.04(stat)±...
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The decays χc1→J/ψμ+μ− and χc2→J/ψμ+μ− are observed and used to study the resonance parameters of the χc1 and χc2 mesons. The masses of these states are measured to be m(χc1)=3510.71±0.04(stat)±0.09(syst) MeV and m(χc2)=3556.10±0.06(stat)±0.11(syst) MeV, where the knowledge of the momentum scale for charged particles dominates the systematic uncertainty. The momentum-scale uncertainties largely cancel in the mass difference m(χc2)−m(χc1)=45.39±0.07(stat)±0.03(syst) MeV. The natural width of the χc2 meson is measured to be Γ(χc2)=2.10±0.20(stat)±0.02(syst) MeV. These results are in good agreement with and have comparable precision to the current world averages.
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.
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 D0→π+π−μ+μ− and D0→K+K−μ+μ− decays is reported using a sample of proton-proton collisions collected by LHCb at a center-of-mass energy of 8 TeV, and corresponding to 2 fb−1 of int...
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The first observation of the D0→π+π−μ+μ− and D0→K+K−μ+μ− decays is reported using a sample of proton-proton collisions collected by LHCb at a center-of-mass energy of 8 TeV, and corresponding to 2 fb−1 of integrated luminosity. The corresponding branching fractions are measured using as normalization the decay D0→K−π+[μ+μ−]ρ0/ω, where the two muons are consistent with coming from the decay of a ρ0 or ω meson. The results are B(D0→π+π−μ+μ−)=(9.64±0.48±0.51±0.97)×10−7 and B(D0→K+K−μ+μ−)=(1.54±0.27±0.09±0.16)×10−7, where the uncertainties are statistical, systematic, and due to the limited knowledge of the normalization branching fraction. The dependence of the branching fraction on the dimuon mass is also investigated.
A search for the B0→K+K− decay is performed using pp-collision data collected by LHCb. The data set corresponds to integrated luminosities of 1.0 and 2.0 fb−1 at center-of-mass energies of 7 and 8 TeV, respectively....
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A search for the B0→K+K− decay is performed using pp-collision data collected by LHCb. The data set corresponds to integrated luminosities of 1.0 and 2.0 fb−1 at center-of-mass energies of 7 and 8 TeV, respectively. This decay is observed for the first time, with a significance of more than 5 standard deviations. The analysis also results in an improved measurement of the branching fraction for the Bs0→π+π− decay. The measured branching fractions are B(B0→K+K−)=(7.80±1.27±0.81±0.21)×10−8 and B(Bs0→π+π−)=(6.91±0.54±0.63±0.19±0.40)×10−7. The first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the B0→K+π− branching fraction used as a normalization. For the Bs0 mode, the fourth accounts for the uncertainty on the ratio of the probabilities for b quarks to hadronize into Bs0 and B0 mesons.
Measurements of the cross section for producing b quarks in the reaction pp→bb¯X are reported in 7 and 13 TeV collisions at the LHC as a function of the pseudorapidity η in the range 2<η<5 covered by the...
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Measurements of the cross section for producing b quarks in the reaction pp→bb¯X are reported in 7 and 13 TeV collisions at the LHC as a function of the pseudorapidity η in the range 2<η<5 covered by the acceptance of the LHCb experiment. The measurements are done using semileptonic decays of b-flavored hadrons decaying into a ground-state charmed hadron in association with a muon. The cross sections in the covered η range are 72.0±0.3±6.8 and 154.3±1.5±14.3 μb for 7 and 13 TeV. The ratio is 2.14±0.02±0.13, where the quoted uncertainties are statistical and systematic, respectively. The agreement with theoretical expectation is good at 7 TeV, but differs somewhat at 13 TeV. The measured ratio of cross sections is larger at lower η than the model prediction.
For high-performance embedded hard-real-time systems, ASICs and FPGAs hold advantages over generalpurpose processors and graphics accelerators (GPUs). However, developing signal processing architectures from scratch r...
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People across the world habitually turn to online social media to share their experiences, thoughts, ideas, and opinions as they go about their daily lives. These posts collectively contain a wealth of insights into h...
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People across the world habitually turn to online social media to share their experiences, thoughts, ideas, and opinions as they go about their daily lives. These posts collectively contain a wealth of insights into how masses perceive their surroundings. Therefore, extracting people's perceptions from social media posts can provide valuable information about pertinent issues such as public transportation, emergency conditions, and even reactions to political actions or other activities. This paper proposes a novel approach to extract such perceptions from a corpus of social media posts originating from a given broad geographical region. The approach divides the broad region into a number of sub-regions, and trains language models over social media conversations within these sub-regions. Using Bayesian and geo-smoothing methods, the ensemble of language models can be queried with phrases embodying a perception. Discrete and continuous visualization methods represent the extent to which social media posts within the sub-regions express the query. The capabilities of the perception mining approach are illustrated using transportation-themed scenarios.
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