Abstract: The invariant-mass distribution for the coherent photoproduction of dipions in ultraperipheral PbPb collisions is measured using data, corresponding to an integrated luminosity of 224.6 +/- 9.6 μb(-1), collected by the LHCb experiment in 2018 at a nucleon-nucleon centre-of-mass energy root s(NN) = 5.02TeV. In the mass range from 400 to 1200MeV, the results are consistent with previous experiments, with the spectrum dominated by the rho(0) meson, which interferes with a nonresonant component, together with a smaller omega meson contribution. In an extended mass range up to 2300MeV, models previously used do not fit the data and a consistent description requires the introduction of two resonances at masses of 1350 +/- 20MeV and 1790 +/- 20MeV with widths of about 300MeV. The cross-section for each meson is measured differentially in twelve bins of rapidity from 2.05 to 4.90. The rho(0) cross-section increases with rapidity from about 400 to 600 mb and is measured with a typical precision of 8%, while the cross-section times branching fraction for the omega, rho' and rho '', with the statistical precision of the data, do not have a pronounced rapidity dependence and are between 0.5 and 1.5mb, with uncertainties up to 30%. A large nuclear suppression is observed for the rho(0) meson compared to expectations based on photoproduction on the proton that use the impulse approximation. Significant suppression is also observed compared to that predicted by elastic scattering described in the Glauber approach, or with the addition of inelastic scattering in a Gribov-Glauber model.

Abstract: The first measurement of phi(1020) meson production in fixed-target pNe collisions at root s(NN) = 68.5 GeV is presented. The phi(1020) mesons are reconstructed in their K+K- decay in a data sample consisting of proton collisions on neon nuclei at rest, corresponding to an integrated luminosity of 21.7 +/- 1.4 nb(-1), collected by the LHCb detector at CERN. The phi(1020) production cross-section in the centre-of-mass rapidity range of -1.8 < y* < 0 and transverse momentum range of 800 < p(T) < 6500MeV/ c is found to be sigma = 182.7 +/- 2.7 (stat.) +/- 14.1 (syst) μb/nucleon. A double-differential measurement of the cross-section is also provided in four regions of rapidity and six regions of transverse momentum of the phi(1020) meson and compared with the predictions from Pythia and EPOS4, which are found to underestimate the experimental values.

Abstract: The production of prompt D+ and D-s(+) mesons is studied in proton-lead collisions at a centre-of-mass energy of root s(NN) = 5.02TeV. The data sample corresponding to an integrated luminosity of (1.58 +/- 0.02)nb(-1) is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using D+ and D-s(+) candidates with transverse momentum in the range of 0 < p(T) < 14 GeV/c and rapidities in the ranges of 1.5 < y* < 4.0 and -5.0 < y* < -2.5 in the nucleon-nucleon centre-of-mass system. For both particles, the nuclear modification factor and the forward-backward production ratio are determined. These results are compared with theoretical models that include initial-state nuclear effects. In addition, measurements of the cross-section ratios between D+, D-s(+) and D-0 mesons are presented, providing a baseline for studying the charm hadronization in lead-lead collisions at LHC energies.

Abstract: We report on a measurement of the Lambda(+)(c) to D-0 production ratio in peripheral PbPb collisions at root sNN = 5.02TeV with the LHCb detector in the forward rapidity region 2 < y < 4.5. The Lambda(+)(c) (D-0) hadrons are reconstructed via the decay channel Lambda(+)(c) -> pK(-)pi(+) (D-0 -> K- pi(+)) for 2 < pT < 8 GeV/ c and in the centrality range of about 65-90%. The results show no significant dependence on pT, y or the mean number of participating nucleons. They are also consistent with similar measurements obtained by the LHCb collaboration in pPb and Pbp collisions at root sNN = 5.02TeV. The data agree well with predictions from PYTHIA in pp collisions at root s = 5TeV but are in tension with predictions of the Statistical Hadronization model.

Abstract: The production of psi(2S) mesons is studied in dimuon final states using proton-lead (pPb) collision data collected by the LHCb detector. The data sample corresponds to an integrated luminosity of 1.6 nb(-1). The nucleon-nucleon centre-of-mass energy of the pPb collisions is root s(NN) = 5 TeV. The measurement is performed using psi(2S) mesons with transverse momentum less than 14 GeV/c and rapidity y in the ranges 1.5 < y < 4.0 and -5.0 < y < -2.5 in the nucleon-nucleon centre-of-mass system. The forward-backward production ratio and the nuclear modi fi cation factor are determined for psi(2S) mesons. Using the production cross-section results of psi(2S) and J/psi mesons from b-hadron decays, the b (b) over bar cross-section in pPb collisions at root s(NN) = 5 TeV is obtained.