The most likely path formalism (MLP) is widely established as the most statistically precise method for proton path reconstruction in proton computed tomography. However, while this method accounts ...for small-angle multiple coulomb scattering (MCS) and energy loss, inelastic nuclear interactions play an influential role in a significant number of proton paths. By applying cuts based on energy and direction, tracks influenced by nuclear interactions are largely discarded from the MLP analysis. In this work we propose a new method to estimate the proton paths based on a deep neural network (DNN). Through this approach, estimates of proton paths equivalent to MLP predictions have been achieved in the case where only MCS occurs, together with an increased accuracy when nuclear interactions are present. Moreover, our tests indicate that the DNN algorithm can be considerably faster than the MLP algorithm.
The first measurement of Formula omitted and Formula omitted production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of Formula omitted and ...Formula omitted mesons is studied with a beam of lead ions with an energy of 2.5 Formula omitted per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of Formula omitted. The Formula omitted/ Formula omitted production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from Formula omitted collisions at the same energy and show no difference in the observed Formula omitted suppression trend when comparing Formula omitted and PbNe peripheral collisions with PbNe central collisions.
Using a proton-proton collision data sample collected by the LHCb detector and corresponding to an integrated luminosity of Formula omitted, the lifetime of the light Formula omitted mass eigenstate, ...Formula omitted, is measured using the Formula omitted decay mode to be tauL=1.445±0.016(stat)±0.008(syst)ps.A combination of this result with a previous LHCb analysis using an independent dataset corresponding to 3 fb Formula omitted of integrated luminosity gives tauL=1.452±0.014±0.007±0.002ps,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 measurement of charmonium states produced in proton-neon ( Formula omitted) collisions by the LHCb experiment in its fixed-target configuration is presented. The production of Formula omitted and ...Formula omitted mesons is studied with a beam of 2.5 Formula omitted protons colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy Formula omitted. The data sample corresponds to an integrated luminosity of Formula omitted nb Formula omitted. The Formula omitted and Formula omitted hadrons are reconstructed in Formula omitted Formula omitted final states. The Formula omitted production cross-section per target nucleon in the centre-of-mass rapidity range Formula omitted is found to be Formula omitted. The ratio of Formula omitted and Formula omitted cross-sections is evaluated to Formula omitted. The Formula omitted to Formula omitted relative production rate is found to be Formula omitted in good agreement with other measurements involving beam and target nuclei of similar sizes.
The very rare Formula omitted decay is searched for by analysing Formula omitted decays. The analysis uses a sample of beauty mesons produced in proton-proton collisions collected with the LHCb ...detector between 2011 and 2018, corresponding to an integrated luminosity of 9 Formula omitted. The signal signature corresponds to simultaneous peaks in the Formula omitted and Formula omitted invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at Formula omitted at Formula omitted confidence level. This is the first limit on the branching fraction of Formula omitted decays and the most stringent limit on Formula omitted decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays.
The first study of Formula omitted violation in the decay mode Formula omitted, with Formula omitted, is presented, exploiting a data sample of proton-proton collisions collected by the LHCb ...experiment that corresponds to an integrated luminosity of Formula omitted. The analysis is performed in bins of phase space, which are optimised for sensitivity to local Formula omitted asymmetries. Formula omitted-violating observables that are sensitive to the angle Formula omitted of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for Formula omitted and Formula omitted decays.
A measurement of Formula omitted meson production by the LHCb experiment in its fixed-target configuration is presented. The production of Formula omitted mesons is studied with a beam of 2.5 Formula ...omitted protons colliding on a gaseous neon target at rest, corresponding to a nucleon-nucleon centre-of-mass energy of Formula omitted. The sum of the Formula omitted and Formula omitted production cross-section in Formula omitted collisions in the centre-of-mass rapidity range Formula omitted is found to be Formula omitted where the first uncertainty is statistical and the second is systematic. The Formula omitted production asymmetry is also evaluated and suggests a trend towards negative values at large negative Formula omitted. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1 Formula omitted intrinsic charm and 10 Formula omitted recombination contributions better describe the data than the other models considered.
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 Formula omitted 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 Formula omitted. The dominant antihyperon contribution, namely Formula omitted decays from promptly produced Formula omitted 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.
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