837 research outputs found

    J/ ψ and D production in √sNN=68.5GeV PbNe collisions

    No full text
    The first measurement of J/ ψ and D production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/ ψ and D mesons is studied with a beam of lead ions with an energy of 2.5 TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of sNN=68.5GeV . The J/ ψ / D production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from pNe collisions at the same energy and show no difference in the observed J/ ψ suppression trend when comparing pNe and PbNe peripheral collisions with PbNe central collision

    J/ψ and D0 production in √sNN=68.5GeV PbNe collisions

    No full text
    The first measurement of J/ ψ and D production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/ ψ and D mesons is studied with a beam of lead ions with an energy of 2.5 TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of sNN=68.5GeV . The J/ ψ / D production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from pNe collisions at the same energy and show no difference in the observed J/ ψ suppression trend when comparing pNe and PbNe peripheral collisions with PbNe central collisions

    J/ψ{{J}/\psi } and D0{{D}} ^0 production in sNN=68.5GeV\sqrt{s_{\scriptscriptstyle \text {NN}}} =68.5\,\text {GeV} PbNe collisions

    No full text
    The first measurement of J/ψJ/\psi and D0D^0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/ψJ/\psi and D0D^0 mesons is studied with a beam of lead ions with an energy of 2.5 TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of sNN\sqrt{s_{\rm NN}} = 68.5 GeV. The J/ψ/D0J/\psi/D^0 production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from ppNe collisions at the same energy. No anomalous J/ψJ/\psi suppression that could indicate the formation of a deconfined medium is observed.The first measurement of J/ψ{{J}/\psi } and D0{{D}} ^0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/ψ{{J}/\psi } and D0{{D}} ^0 mesons is studied with a beam of lead ions with an energy of 2.5TeV\,\text {TeV} per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of sNN=68.5GeV\sqrt{s_{\scriptscriptstyle \text {NN}}} =68.5\,\text {GeV} . The J/ψ{{J}/\psi }/D0{{D}} ^0 production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from pNep\text {Ne} collisions at the same energy and show no difference in the observed J/ψ{{J}/\psi } suppression trend when comparing pNep\text {Ne} and PbNe peripheral collisions with PbNe central collisions.The first measurement of J/ψJ/\psi and D0D^0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/ψJ/\psi and D0D^0 mesons is studied with a beam of lead ions with an energy of 2.5 TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of sNN\sqrt{s_{\rm NN}} = 68.5 GeV. The J/ψ/D0J/\psi/D^0 production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from ppNe collisions at the same energy and show no difference in the observed J/ψJ/\psi suppresion trend when comparing ppNe and PbNe peripheral collisions with PbNe central collisions

    Measurement of D0D0D^0-\overline{D}^0 mixing and search for CPCP violation with D0K+πD^0\rightarrow K^+\pi^- decays

    No full text
    A measurement of the time-dependent ratio of the D0K+πD^0\rightarrow K^+\pi^- to D0K+π\overline{D}^0\rightarrow K^+\pi^- decay rates is reported. The analysis uses a sample of proton-proton collisions corresponding to an integrated luminosity of 6 fb1^-1 recorded by the LHCb experiment from 2015 through 2018 at a center-of-mass energy of 13 TeV. The D0D^0 meson is required to originate from a D+D0π+D^{*+}\rightarrow D^0\pi^+ decay, such that its flavor at production is inferred from the charge of the accompanying pion. The measurement is performed simultaneously for the K+πK^+\pi^- and Kπ+K^-\pi^+ final states, allowing both mixing and CPCP-violation parameters to be determined. The value of the ratio of the decay rates at production is determined to be RKπ=(343.1±2.0)×105R_{K\pi} = (343.1 \pm 2.0) \times 10^{-5}. The mixing parameters are measured to be cKπ=(51.4±3.5)×104c_{K\pi} = (51.4 \pm 3.5) \times 10^{-4} and cKπ=(13±4)×106c_{K\pi}^{\prime} = (13 \pm 4) \times 10^{-6}, where RKπcKπ\sqrt{R_{K\pi}}c_{K\pi} is the linear coefficient of the expansion of the ratio as a function of decay time in units of the D0D^0 lifetime, and cKπc_{K\pi}^{\prime} is the quadratic coefficient, both averaged between the K+πK^+\pi^- and Kπ+K^-\pi^+ final states. The precision is improved relative to the previous best measurement by approximately 60%. No evidence for CPCP violation is found.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/Publications/LHCbProjectPublic/LHCb-PAPER-2024-008.htm

    Observation of the B0s → D*+ D*- decay

    No full text
    The first observation of the Bs0 → D ∗+ D ∗− decay and the measurement of its branching ratio relative to the B 0 → D ∗+ D ∗− decay are presented. The data sample used corresponds to an integrated luminosity of 9 fb −1 of proton-proton collisions recorded by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018. The decay is observed with more than 10 standard deviations and the time-integrated ratio of branching fractions is determined to be B(Bs0→D∗+D∗−)B(B0→D∗+D∗−)=0.269±0.032±0.011±0.008, where the first uncertainty is statistical, the second systematic and the third due to the uncertainty of the fragmentation fraction ratio fs /fd. The Bs0 → D *+ D *− branching fraction is calculated to be B(Bs0→D∗+D∗−)=(2.15±0.26±0.09±0.06±0.16)×10−4, where the fourth uncertainty is due to the B 0 → D *+ D *− branching fraction. These results are calculated using the average Bs0 meson lifetime in simulation. Correction factors are reported for scenarios where either a purely heavy or a purely light Bs0 eigenstate is considered. [Figure not available: see fulltext.]

    Observation of the B0→ ̄D*0K+π− and B0s→ ̄D*0K−π+ decays

    No full text
    The first observations of B0→D ̄∗(2007)0K+π- and Bs0→D ̄∗(2007)0K-π+ decays are presented, and their branching fractions relative to that of the B0→D ̄∗(2007)0π+π- decay are reported. These modes can potentially be used to investigate the spectroscopy of charm and charm-strange resonances and to determine the angle γ of the Cabibbo-Kobayashi-Maskawa unitarity triangle. It is also important to understand them as a source of potential background in determinations of γ from B+→DK+ and B0→DK+π- decays. The analysis is based on a sample corresponding to an integrated luminosity of 5.4 fb-1 of proton-proton collision data at 13 TeV center-of-mass energy recorded with the LHCb detector. The D ̄∗(2007)0 mesons are fully reconstructed in the D ̄0π0 and D ̄0γ channels with the D ̄0→K+π- decay. A novel weighting method is used to subtract background while simultaneously applying an event-by-event efficiency correction to account for resonant structures in the decays

    First observation of the Λb0→ D+D−Λ decay

    No full text
    The Λb0 → D+D−Λ decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.3 fb−1. Using the B0 → D+D−KS0 decay as a reference channel, the product of the relative production cross-section and decay branching fractions is measured to be (Formula presented.) where the first uncertainty is statistical and the second is systematic. The known branching fraction of the reference channel, BB0→D+D−KS0, and the cross-section ratio, σΛb0/σB0, previously measured by LHCb are used to derive the branching fraction of the Λb0→ D+D−Λ decay (Formula presented.) where the third and fourth contributions are due to uncertainties of BB0→D+D−KS0 and σΛb0/σB0, respectively. Inspection of the D+Λ and D+D− invariant-mass distributions suggests a rich presence of intermediate resonances in the decay. The Λb0 → D*+D−Λ decay is also observed for the first time as a partially reconstructed component in the D+D−Λ invariant mass spectrum

    Test of lepton flavor universality using B0 →D∗-τ+ντ decays with hadronic τ channels

    No full text
    The branching fraction B(B0→D∗-τ+ντ) is measured relative to that of the normalization mode B0→D∗-π+π-π+ using hadronic τ+→π+π-π+(π0)ν ̄τ decays in proton-proton collision data at a center-of-mass energy of 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb-1. The measured ratio is B(B0→D∗-τ+ντ)/B(B0→D∗-π+π-π+)=1.70±0.10-0.10+0.11, where the first uncertainty is statistical and the second is related to systematic effects. Using established branching fractions for the B0→D∗-π+π-π+ and B0→D∗-μ+νμ modes, the lepton universality test R(D∗-)B(B0→D∗-τ+ντ)/B(B0→D∗-μ+νμ) is calculated, R(D∗-)=0.247±0.015±0.015±0.012, where the third uncertainty is due to the uncertainties on the external branching fractions. This result is consistent with the Standard Model prediction and with previous measurements

    Amplitude analysis of the B+ →d+D-K+ decay

    No full text
    Results are reported from an amplitude analysis of the B+→D+D-K+ decay. The analysis is carried out using LHCb proton-proton collision data taken at s=7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb-1. In order to obtain a good description of the data, it is found to be necessary to include new spin-0 and spin-1 resonances in the D-K+ channel with masses around 2.9 GeV/c2, and a new spin-0 charmonium resonance in proximity to the spin-2 χc2(3930) state

    Measurement of branching fraction ratios for B+ → D*+D−K+, B+ → D*−D+K+, and B0 → D*−D0K+ decays

    No full text
    A measurement of four branching-fraction ratios for three-body decays of B mesons involving two open-charm hadrons in the final state is presented. Run 1 and Run 2 pp collision data are used, recorded by the LHCb experiment at centre-of-mass energies 7, 8, and 13 TeV and corresponding to an integrated luminosity of 9 fb−1. The measured branching-fraction ratios areB(B+→D∗+D−K+)B(B+→D ̄0D0K+)=0.517±0.015±0.013±0.011,B(B+→D∗−D+K+)B(B+→D ̄0D0K+)=0.577±0.016±0.013±0.013,B(B0→D∗−D0K+)B(B0→D−D0K+)=1.754±0.028±0.016±0.035,B(B+→D∗+D−K+)B(B+→D∗−D+K+)=0.907±0.033±0.014, where the first of the uncertainties is statistical, the second systematic, and the third is due to the uncertainties on the D-meson branching fractions. These are the most accurate measurements of these ratios to date. [Figure not available: see fulltext.
    corecore