73 research outputs found

    On the prompt contribution to the atmospheric neutrino flux

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    The prompt contribution to the atmospheric neutrino flux is analyzed. It is demonstrated that the corresponding theoretical uncertainties related to perturbative treatment of charm production, notably, the ones stemming from the low and high xx behavior of parton distribution functions, can be conveniently studied at the level of charm quark production. Additionally, we discuss the non-perturbative contribution to the prompt neutrino flux, related to the intrinsic charm content of the proton, and analyze its main features.Comment: v2: accepted versio

    Forward production of prompt neutrinos from charm in the atmosphere and at high energy colliders

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    The high-energy atmospheric neutrino flux is dominated by neutrinos from the decays of charmed hadrons produced in the forward direction by cosmic ray interactions with air nuclei. We evaluate the charm contributions to the prompt atmospheric neutrino flux as a function of the center-of-mass energy s\sqrt{s} of the hadronic collision and of the center-of-mass rapidity yy of the produced charm hadron. Uncertainties associated with parton distribution functions are also evaluated as a function of yy. We find that the yy coverage of LHCb for forward heavy-flavour production, complemented by the angular coverage of present and future forward neutrino experiments at the LHC, bracket the most interesting yy regions for the prompt atmospheric neutrino flux. At s=14\sqrt{s}=14 TeV foreseen for the HL-LHC phase, nucleon collisions in air contribute to the prompt neutrino flux prominently below Eν107E_\nu\sim 10^7~GeV. Measurements of forward charm and/or forward neutrinos produced in hadron collisions up to s=100\sqrt{s}=100 TeV, which might become possible at the FCC, are relevant for the prompt atmospheric neutrino flux up to Eν=108E_\nu=10^8 GeV and beyond.Comment: 29 pages, 11 figure

    Impact of heavy-flavour production cross sections measured by the LHCb experiment on parton distribution functions at low x

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    The impact of recent measurements of heavy-flavour production in deep inelastic epep scattering and in pppp collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions xx of the proton momentum, down to x5×106x \sim 5 \times 10^{-6}. This kinematic range is currently not covered by other experimental data in perturbative QCD fits