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We present a model which describes proton scattering data from ISR to Tevatron energies, and which can be applied to collimation in high energy accelerators, such as the LHC and FCC. Collimators remove beam halo particles, so that they do not impinge on vulnerable regions of the machine, such as the superconducting magnets and the experimental areas. In simulating the effect of the collimator jaws it is crucial to model the scattering of protons at small momentum transfer  t , as these protons can subsequently survive several turns of the ring before being lost. At high energies these soft processes are well described by Pomeron exchange models. We study the behaviour of elastic and single-diffractive dissociation cross sections over a wide range of energy, and show that the model can be used as a global description of the wide variety of high energy elastic and diffractive data presently available. In particular it models low mass diffraction dissociation, where a rich resonance structure is present, and thus predicts the differential and integrated cross sections in the kinematical range appropriate to the LHC. We incorporate the physics of this model into the beam tracking code MERLIN and use it to simulate the resulting loss maps of the beam halo lost in the collimators in the LHC.

The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for pair-produced charged Higgs bosons in the framework of Two Higgs Doublet Models (2HDMs). The data of the four experiments have been statistically combined. The results are interpreted within the 2HDM for Type I and Type II benchmark scenarios. No statistically significant excess has been observed when compared to the Standard Model background prediction, and the combined LEP data exclude large regions of the model parameter space. Charged Higgs bosons with mass below 80  (Type II scenario) or 72.5 (Type I scenario, for pseudo-scalar masses above 12 ) are excluded at the 95 % confidence level.

The calibration and performance of the opposite-side flavour tagging algorithms used for the measurements of time-dependent asymmetries at the LHCb experiment are described. The algorithms have been developed using simulated events and optimized and calibrated with B + → J / ψK + , B 0 → J / ψK ∗0 and B 0 → D ∗− μ + ν μ decay modes with 0.37 fb −1 of data collected in pp collisions at during the 2011 physics run. The opposite-side tagging power is determined in the B + → J / ψK + channel to be (2.10±0.08±0.24) %, where the first uncertainty is statistical and the second is systematic.

The polarimeter vector field for multibody decays of a spin-half baryon is intro duced as a generalisation of the baryon asymmetry parameters. Using a recent amplitude analysis of the Λ_(c)⁺ → pK⁻π⁺ decay performed at the LHCb experiment, we compute the distribution of the kinematic-dependent polarimeter vector for this process in the space of Mandelstam variables to express the polarised decay rate in a model-agnostic form. The obtained representation can facilitate polarisation measurements of the Λ_(c)⁺ baryon and eases inclusion of the Λ_(c)⁺ → pK⁻π⁺ decay mode in hadronic amplitude analyses.

An angular analysis of the B-s(0)-> phi e(+)e(-) decay is performed using the proton-proton collision dataset collected between 2011 and 2018 by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1) at centre-of-mass energies of 7, 8 and 13 TeV. The analysis is performed in the very low dielectron invariant mass-squared region between 0.0009 and 0.2615 GeV2/c(4). The longitudinal polarisation fraction of the phi meson is measured to be less than 11.5% at 90% confidence level. The A(T)(ReCP) observable, which is related to the lepton forward-backward asymmetry, is measured to be 0.116 +/- 0.155 +/- 0.006, where the first uncertainty is statistical and the second systematic. The transverse asymmetries, A(T)((2)) and A(T)(ImCP), which are sensitive to the virtual photon polarisation, are found to be -0.045 +/- 0.235 +/- 0.014 and 0.002 +/- 0.247 +/- 0.016, respectively. The results are consistent with Standard Model predictions.

The first measurement of J/ψ and D ⁰ production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/ψ and D 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 √s̅_̅(̅\\̅s̅c̅r̅i̅p̅t̅s̅c̅r̅i̅p̅t̅s̅t̅y̅l̅e̅ ̅\\̅t̅e̅x̅t̅ ̅N̅N̅)̅ =68.5 \\text GeV. The J/ψ /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 p\\text Ne collisions at the same energy and show no difference in the observed J/ψ suppression trend when comparing p\\text Ne and PbNe peripheral collisions with PbNe central collisions. Similar content being vie

The measurement of charmonium states produced in proton-neon (pNe) collisions by the LHCb experiment in its fixed-target configuration is presented. The pro duction of J/ψ and ψ(2S) mesons is studied with a beam of 2.5 TeV protons colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy √s̅_̅(̅N̅N̅)̅ = 68.5 GeV. The data sample corresponds to an integrated luminosity of 21.7 ± 1.4 nb-1. The J/ψ and ψ(2S) hadrons are reconstructed in μ+μ- final states. The J/ψ production cross-section per target nucleon in the centre-of mass rapidity range y* ϵ [-2.29, 0] is found to be 506 ± 8 ± 46 nb/nucleon. The ratio of J/ψ and D0 cross-sections is evaluated to (1.06 ± 0.02 ± 0.09)%. The ψ(2S) to J/ψ relative production rate is found to be (1.67 ± 0.27 ± 0.10)% in good agreement with other measurements involving beam and target nuclei of similar sizes.

Using a proton–proton collision data sample collected by the LHCb detector and corresponding to an integrated luminosity of $5.7~\\text {fb}^{-1}$ , the lifetime of the light ${{B} ^0_{s}}$ mass eigenstate, $\\tau _{L}$ , is measured using the $B^0_s \\rightarrow J/\\psi \\eta$ decay mode to be $\\begin{aligned} \\tau _{\\text {L}} = 1.445 \\pm 0.016 \\text {(stat)} \\pm 0.008 \\text {(syst)} \\,\\text {ps}. \\end{aligned}$ A combination of this result with a previous LHCb analysis using an independent dataset corresponding to 3 fb–1 of integrated luminosity gives $\\begin{aligned} \\tau _{\\text {L}} = 1.452 \\pm 0.014 \\pm 0.007 \\pm 0.002 \\,\\text {ps}, \\end{aligned}$ where the first uncertainty is statistical, the second due to the uncorrelated part of the systematic uncertainty and the third due to the correlated part of the systematic uncertainty.

The interpretation of cosmic antiproton flux measurements from space-borne experiments is currently limited by the knowledge of the antiproton production cross-section in collisions between primary cosmic rays and the interstellar medium. Using collisions of protons with an energy of 6.5$$\\,\\text {Te\\hspace{-1.00006pt}V}$$Te V incident on helium nuclei at rest in the proximity of the interaction region of the LHCb experiment, the ratio of antiprotons originating from antihyperon decays to prompt production is measured for antiproton momenta between 12 and$$110\\,\\text {Ge\\hspace{-1.00006pt}V\\!/}c $$110 Ge V\\!/ c . The dominant antihyperon contribution, namely$${\\overline{\\varLambda }} \\rightarrow {\\overline{{p}}} {{\\pi } ^+} $$Λ ¯ → p ¯ π + decays from promptly produced$$\\overline{\\varLambda }$$Λ ¯ particles, is also exclusively measured. The results complement the measurement of prompt antiproton production obtained from the same data sample. At the energy scale of this measurement, the antihyperon contributions to antiproton production are observed to be significantly larger than predictions of commonly used hadronic production models.

A measurement of CP-violating observables is performed using the decays B $^{±}$→ DK $^{±}$and B $^{±}$→ Dπ $^{±}$ , where the D meson is reconstructed in one of the self-conjugate three-body final states$ {K}_{\\mathrm{S}}^0 $ π $^{+}$ π $^{−}$and$ {K}_{\\mathrm{S}}^0 $ K $^{+}$ K $^{−}$(commonly denoted$ {K}_{\\mathrm{S}}^0 $ h $^{+}$ h $^{−}$ ). The decays are analysed in bins of the D-decay phase space, leading to a measurement that is independent of the modelling of the D-decay amplitude. The observables are inter- preted in terms of the CKM angle γ. Using a data sample corresponding to an integrated luminosity of 9 fb $^{−1}$collected in proton-proton collisions at centre-of mass energies of 7, 8, and 13 TeV with the LHCb experiment, γ is measured to be$ \\left({68.7}_{-5.1}^{+5.2}\\right){}^{\\circ} $ . The hadronic parameters$ {r}_B^{D K},{r}_B^{D\\pi},{\\delta}_B^{D K},\\kern0.5em \\mathrm{and}\\kern0.5em {\\delta}_B^{D\\pi} $ , which are the ratios and strong-phase differences of the suppressed and favoured B $^{±}$decays, are also reported.[graphic not available: see fulltext]