21 research outputs found

    Observation of the very rare Σ+pμ+μ\Sigma^+ \to p \mu^+ \mu^- decay

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    International audienceThe first observation of the Σ+pμ+μ\Sigma^+ \to p \mu^+ \mu^- decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 5.4fb15.4\,\rm{fb}^{-1}, collected with the LHCb detector at a centre-of-mass energy of 13~TeV. A yield of 237±16237\pm 16Σ+pμ+μ\Sigma^+ \to p \mu^+ \mu^- decays is obtained, where the uncertainty is statistical only. A branching fraction of (1.08±0.17)×108(1.08 \pm 0.17) \times 10^{-8} is measured, where the uncertainty includes statistical and systematic sources. No evidence of resonant structures is found in the dimuon invariant-mass distribution. All results are compatible with Standard Model expectations. This represents the rarest decay of a baryon ever observed

    First measurement of bb-jet mass with and without grooming

    No full text
    International audienceThe LHCb collaboration presents a novel suite of heavy-flavour jet substructure measurements at forward rapidity in proton-proton collisions at a centre-of-mass energy of s=13\sqrt{s} = 13 TeV. The jet mass is a perturbatively calculable probe of the virtuality of hard-scattered quarks and gluons, connecting small-distance quantum chromodynamics (QCD) with long-distance experimental measurement. It becomes dominated by nonperturbative corrections at small values, presenting an excellent test of QCD across a broad range of energies. Measuring heavy-flavour jet mass with a theoretically unambiguous flavour definition for the first time probes the gluon splitting mechanism for heavy-flavour production and pushes tests of perturbative QCD to unprecedented theoretical precision. Utilising the soft drop jet-grooming technique to access the perturbative jet core further enhances constraints on first-principles theory. Measurements of the jet mass for jets containing fully reconstructed B±B^\pm hadrons are reported with and without grooming. These results offer unparalleled tests of quark flavour and mass dependence in QCD and provide a baseline for future studies of heavy-flavour jet quenching in heavy-ion collisions

    First measurement of bb-jet mass with and without grooming

    No full text
    International audienceThe LHCb collaboration presents a novel suite of heavy-flavour jet substructure measurements at forward rapidity in proton-proton collisions at a centre-of-mass energy of s=13\sqrt{s} = 13 TeV. The jet mass is a perturbatively calculable probe of the virtuality of hard-scattered quarks and gluons, connecting small-distance quantum chromodynamics (QCD) with long-distance experimental measurement. It becomes dominated by nonperturbative corrections at small values, presenting an excellent test of QCD across a broad range of energies. Measuring heavy-flavour jet mass with a theoretically unambiguous flavour definition for the first time probes the gluon splitting mechanism for heavy-flavour production and pushes tests of perturbative QCD to unprecedented theoretical precision. Utilising the soft drop jet-grooming technique to access the perturbative jet core further enhances constraints on first-principles theory. Measurements of the jet mass for jets containing fully reconstructed B±B^\pm hadrons are reported with and without grooming. These results offer unparalleled tests of quark flavour and mass dependence in QCD and provide a baseline for future studies of heavy-flavour jet quenching in heavy-ion collisions

    Angular analysis of the decay Bs0ϕe+eB_{s}^{0}\to\phi e^+e^-

    No full text
    International audienceAn angular analysis of the decay Bs0ϕe+eB^0_s\to\phi e^+e^- is presented, using proton-proton collision data collected with the LHCb detector between 2011 and 2018 at centre-of-mass energies of 7, 8 and 13TeV\,\mathrm{Te\kern -0.1em V}. The combined dataset corresponds to an integrated luminosity of 9fb19\,\mathrm{fb}^{-1}. Observables are determined by fitting time-integrated projections of the angular distribution in three bins of dielectron mass squared, q2q^2, corresponding to [0.1,1.1][0.1,1.1], [1.1,6.0][1.1,6.0] and [15.0,19.0]GeV2 ⁣/c4[15.0,19.0]\,\mathrm{Ge\kern -0.1em V}^2\!/c^4. The results are compatible with predictions based on the Standard Model of particle physics

    First measurement of bb-jet mass with and without grooming

    No full text
    International audienceThe LHCb collaboration presents a novel suite of heavy-flavour jet substructure measurements at forward rapidity in proton-proton collisions at a centre-of-mass energy of s=13\sqrt{s} = 13 TeV. The jet mass is a perturbatively calculable probe of the virtuality of hard-scattered quarks and gluons, connecting small-distance quantum chromodynamics (QCD) with long-distance experimental measurement. It becomes dominated by nonperturbative corrections at small values, presenting an excellent test of QCD across a broad range of energies. Measuring heavy-flavour jet mass with a theoretically unambiguous flavour definition for the first time probes the gluon splitting mechanism for heavy-flavour production and pushes tests of perturbative QCD to unprecedented theoretical precision. Utilising the soft drop jet-grooming technique to access the perturbative jet core further enhances constraints on first-principles theory. Measurements of the jet mass for jets containing fully reconstructed B±B^\pm hadrons are reported with and without grooming. These results offer unparalleled tests of quark flavour and mass dependence in QCD and provide a baseline for future studies of heavy-flavour jet quenching in heavy-ion collisions

    Angular analysis of the decay Bs0ϕe+eB_{s}^{0}\to\phi e^+e^-

    No full text
    International audienceAn angular analysis of the decay Bs0ϕe+eB^0_s\to\phi e^+e^- is presented, using proton-proton collision data collected with the LHCb detector between 2011 and 2018 at centre-of-mass energies of 7, 8 and 13TeV\,\mathrm{Te\kern -0.1em V}. The combined dataset corresponds to an integrated luminosity of 9fb19\,\mathrm{fb}^{-1}. Observables are determined by fitting time-integrated projections of the angular distribution in three bins of dielectron mass squared, q2q^2, corresponding to [0.1,1.1][0.1,1.1], [1.1,6.0][1.1,6.0] and [15.0,19.0]GeV2 ⁣/c4[15.0,19.0]\,\mathrm{Ge\kern -0.1em V}^2\!/c^4. The results are compatible with predictions based on the Standard Model of particle physics
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