ORCID Profile
0000-0002-9264-4799
Current Organisation
The University of Edinburgh
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Publisher: Springer Science and Business Media LLC
Date: 07-2022
Abstract: A precision measurement of the Z boson production cross-section at $$ \\sqrt{\\mathrm{s}} $$ s = 13 TeV in the forward region is presented, using pp collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb − 1 . The production cross-section is measured using Z → μ + μ − events within the fiducial region defined as pseudorapidity 2 . 0 η 4 . 5 and transverse momentum p T 20 GeV /c for both muons and dimuon invariant mass 60 M μμ 120 GeV /c 2 . The integrated cross-section is determined to be $$ \\sigma \\left(Z\\to {\\mu}^{+}{\\mu}^{-}\\right)=196.4\\pm 0.2\\pm 1.6\\pm 3.9\\ \\mathrm{pb}, $$ σ Z → μ + μ − = 196.4 ± 0.2 ± 1.6 ± 3.9 pb , where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions within uncertainties.
Publisher: Springer Science and Business Media LLC
Date: 02-01-2202
DOI: 10.1140/EPJC/S10052-023-11759-6
Abstract: The very rare $${{D} ^*} (2007)^0\\!\\rightarrow {\\mu ^+\\mu ^-} $$ D ∗ ( 2007 ) 0 → μ + μ - decay is searched for by analysing $${{{B} ^-}} \\!\\rightarrow {{\\pi } ^-} {\\mu ^+\\mu ^-} $$ B - → π - μ + μ - decays. The analysis uses a s le of beauty mesons produced in proton–proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 $$\\text {\\,fb} ^{-1}$$ \\,fb - 1 . The signal signature corresponds to simultaneous peaks in the $${\\mu ^+\\mu ^-} $$ μ + μ - and $${{\\pi } ^-} {\\mu ^+\\mu ^-} $$ π - μ + μ - 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 $$\\mathcal{B}({{D} ^*} (2007)^0\\!\\rightarrow {\\mu ^+\\mu ^-} ) 2.6\\times 10^{-8}$$ B ( D ∗ ( 2007 ) 0 → μ + μ - ) 2.6 × 10 - 8 at $$90\\%$$ 90 % confidence level. This is the first limit on the branching fraction of $${{D} ^*} (2007)^0\\!\\rightarrow {\\mu ^+\\mu ^-} $$ D ∗ ( 2007 ) 0 → μ + μ - decays and the most stringent limit on $${{D} ^*} (2007)^0$$ D ∗ ( 2007 ) 0 decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays.
Publisher: Springer Science and Business Media LLC
Date: 17-07-2023
DOI: 10.1140/EPJC/S10052-023-11608-6
Abstract: The measurement of charmonium states produced in proton-neon ( $$p\\text {Ne}$$ p Ne ) collisions by the LHCb experiment in its fixed-target configuration is presented. The production of $${{J} \\hspace{-1.66656pt}/\\hspace{-1.111pt}\\psi }$$ J / ψ and $$\\psi {(2S)}$$ ψ ( 2 S ) mesons is studied with a beam of 2.5 $$\\mathrm{\\,Te\\hspace{-1.00006pt}V}$$ Te V protons colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy $$\\sqrt{s_{\\scriptscriptstyle \\text {NN}}} =68.5\\mathrm{\\,Ge\\hspace{-1.00006pt}V} $$ s NN = 68.5 Ge V . The data s le corresponds to an integrated luminosity of $$21.7\\pm 1.4 $$ 21.7 ± 1.4 nb $$^{-1}$$ - 1 . The $${{J} \\hspace{-1.66656pt}/\\hspace{-1.111pt}\\psi }$$ J / ψ and $$\\psi {(2S)}$$ ψ ( 2 S ) hadrons are reconstructed in $$\\mu ^+$$ μ + $$\\mu ^-$$ μ - final states. The $${{J} \\hspace{-1.66656pt}/\\hspace{-1.111pt}\\psi }$$ J / ψ production cross-section per target nucleon in the centre-of-mass rapidity range $$y^\\star \\in [-2.29, 0]$$ y ⋆ ∈ [ - 2.29 , 0 ] is found to be $$506 \\pm 8 \\pm 46 \\text { nb/nucleon}$$ 506 ± 8 ± 46 nb/nucleon . The ratio of $${{J} \\hspace{-1.66656pt}/\\hspace{-1.111pt}\\psi }$$ J / ψ and $$D^0$$ D 0 cross-sections is evaluated to $$(1.06 \\pm 0.02 \\pm 0.09)\\%$$ ( 1.06 ± 0.02 ± 0.09 ) % . The $$\\psi {(2S)}$$ ψ ( 2 S ) to $${{J} \\hspace{-1.66656pt}/\\hspace{-1.111pt}\\psi }$$ J / ψ relative production rate is found to be $$(1.67 \\pm 0.27\\pm 0.10)\\%$$ ( 1.67 ± 0.27 ± 0.10 ) % in good agreement with other measurements involving beam and target nuclei of similar sizes.
Publisher: American Physical Society (APS)
Date: 03-08-2023
Publisher: American Physical Society (APS)
Date: 17-07-2023
Publisher: American Physical Society (APS)
Date: 04-08-2023
Publisher: American Physical Society (APS)
Date: 29-08-2023
Publisher: American Physical Society (APS)
Date: 29-08-2023
Publisher: Springer Science and Business Media LLC
Date: 29-06-2023
DOI: 10.1140/EPJC/S10052-023-11560-5
Abstract: The first study of $$C\\!P$$ C P violation in the decay mode $${{B} ^\\pm } \\rightarrow [{{K} ^+} {{K} ^-} {{\\uppi } ^+} {{\\uppi } ^-} ]_{D} h^\\pm $$ B ± → [ K + K - π + π - ] D h ± , with $$h=K,\\pi $$ h = K , π , is presented, exploiting a data s le of proton–proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of $$9\\text {\\,fb} ^{-1} $$ 9 \\,fb - 1 . The analysis is performed in bins of phase space, which are optimised for sensitivity to local $$C\\!P$$ C P asymmetries. $$C\\!P$$ C P -violating observables that are sensitive to the angle $$\\gamma $$ γ of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an litude 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 $${{B} ^\\pm } \\rightarrow [{{K} ^+} {{K} ^-} {{\\uppi } ^+} {{\\uppi } ^-} ]_{D} h^\\pm $$ B ± → [ K + K - π + π - ] D h ± and $${{B} ^\\pm } \\rightarrow [{{\\uppi } ^+} {{\\uppi } ^-} {{\\uppi } ^+} {{\\uppi } ^-} ]_{D} h^\\pm $$ B ± → [ π + π - π + π - ] D h ± decays.
Publisher: American Physical Society (APS)
Date: 06-09-2023
Publisher: IOP Publishing
Date: 10-2023
Publisher: American Physical Society (APS)
Date: 26-09-2023
Publisher: American Physical Society (APS)
Date: 06-09-2023
Publisher: American Physical Society (APS)
Date: 24-08-2022
Publisher: American Physical Society (APS)
Date: 13-07-2023
Publisher: American Physical Society (APS)
Date: 26-09-2023
Publisher: American Physical Society (APS)
Date: 14-07-2023
Publisher: American Physical Society (APS)
Date: 18-09-2023
Publisher: American Physical Society (APS)
Date: 28-07-2023
Publisher: American Physical Society (APS)
Date: 27-07-2023
Publisher: American Physical Society (APS)
Date: 26-07-2023
Publisher: American Physical Society (APS)
Date: 23-10-2023
Publisher: American Physical Society (APS)
Date: 14-08-2023
Publisher: American Physical Society (APS)
Date: 23-10-2023
Publisher: American Physical Society (APS)
Date: 28-07-0154
Publisher: Springer Science and Business Media LLC
Date: 17-07-2023
DOI: 10.1140/EPJC/S10052-023-11634-4
Abstract: Using a proton–proton collision data s le collected by the LHCb detector and corresponding to an integrated luminosity of $$5.7~\\text {fb}^{-1}$$ 5.7 fb - 1 , the lifetime of the light $${{B} ^0_{s}} $$ B s 0 mass eigenstate, $$\\tau _{L}$$ τ L , is measured using the $$B^0_s \\rightarrow J/\\psi \\eta $$ B s 0 → J / ψ η decay mode to be $$\\begin{aligned} \\tau _{\\text {L}} = 1.445 \\pm 0.016 \\text {(stat)} \\pm 0.008 \\text {(syst)} \\,\\text {ps}. \\end{aligned}$$ τ L = 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 $$^{-1}$$ - 1 of integrated luminosity gives $$\\begin{aligned} \\tau _{\\text {L}} = 1.452 \\pm 0.014 \\pm 0.007 \\pm 0.002 \\,\\text {ps}, \\end{aligned}$$ τ L = 1.452 ± 0.014 ± 0.007 ± 0.002 ps , 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.
Publisher: American Physical Society (APS)
Date: 17-08-2023
Publisher: American Physical Society (APS)
Date: 27-07-2023
Publisher: American Physical Society (APS)
Date: 10-08-2023
Publisher: Springer Science and Business Media LLC
Date: 2022
Abstract: The W boson mass is measured using proton-proton collision data at $$ \\sqrt{s} $$ s = 13 TeV corresponding to an integrated luminosity of 1.7 fb − 1 recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon q T distribution of a s le of W → μν decays and the ϕ * distribution of a s le of Z → μμ decays the W boson mass is determined to be $$ {m}_w=80354\\pm {23}_{\\mathrm{stat}}\\pm {10}_{\\mathrm{exp}}\\pm {17}_{\\mathrm{theory}}\\pm {9}_{\\mathrm{PDF}}\\mathrm{MeV}, $$ m w = 80354 ± 23 stat ± 10 exp ± 17 theory ± 9 PDF MeV , where uncertainties correspond to contributions from statistical, experimental systematic, theoretical and parton distribution function sources. This is an average of results based on three recent global parton distribution function sets. The measurement agrees well with the prediction of the global electroweak fit and with previous measurements.
Publisher: American Physical Society (APS)
Date: 27-07-2023
Publisher: American Physical Society (APS)
Date: 14-08-2023
Publisher: American Physical Society (APS)
Date: 02-08-2023
Publisher: American Physical Society (APS)
Date: 13-09-2023
Publisher: American Physical Society (APS)
Date: 24-07-2023
Publisher: Springer Science and Business Media LLC
Date: 28-07-2023
Publisher: American Physical Society (APS)
Date: 27-07-2023
Publisher: American Physical Society (APS)
Date: 08-08-2023
Publisher: American Physical Society (APS)
Date: 27-07-2023
Publisher: American Physical Society (APS)
Date: 10-10-2023
Publisher: American Physical Society (APS)
Date: 02-08-2023
Publisher: American Physical Society (APS)
Date: 20-07-2023
Publisher: Springer Science and Business Media LLC
Date: 27-06-2023
DOI: 10.1140/EPJC/S10052-023-11673-X
Abstract: 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 s le. 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.
Publisher: Springer Science and Business Media LLC
Date: 25-07-2023
DOI: 10.1140/EPJC/S10052-023-11674-W
Abstract: The first measurement of $${{J}/\\psi }$$ J / ψ and $${{D}} ^0$$ D 0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of $${{J}/\\psi }$$ J / ψ and $${{D}} ^0$$ D 0 mesons is studied with a beam of lead ions with an energy of 2.5 $$\\,\\text {TeV}$$ TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of $$\\sqrt{s_{\\scriptscriptstyle \\text {NN}}} =68.5\\,\\text {GeV} $$ s NN = 68.5 GeV . The $${{J}/\\psi }$$ J / ψ / $${{D}} ^0$$ 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 $$p\\text {Ne}$$ p Ne collisions at the same energy and show no difference in the observed $${{J}/\\psi }$$ J / ψ suppression trend when comparing $$p\\text {Ne}$$ p Ne and PbNe peripheral collisions with PbNe central collisions.
Publisher: Springer Science and Business Media LLC
Date: 08-08-2023
Publisher: Springer Science and Business Media LLC
Date: 27-06-2023
DOI: 10.1140/EPJC/S10052-023-11641-5
Abstract: A measurement of $${{D}} ^0$$ D 0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of $${{D}} ^0$$ D 0 mesons is studied with a beam of 2.5 $$\\,\\text {Te\\hspace{-1.00006pt}V}$$ Te V protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of $$\\sqrt{s_{\\scriptscriptstyle \\text {NN}}} = 68.5\\,\\,\\text {Ge\\hspace{-1.00006pt}V} $$ s NN = 68.5 Ge V . The sum of the $${{D}} ^0$$ D 0 and $${\\hspace{0.0pt}\\overline{\\hspace{0.0pt}{D}}} {}^0$$ D ¯ 0 production cross-section in $$p\\text {Ne}$$ p Ne collisions in the centre-of-mass rapidity range $$y^{\\star }\\in [-2.29, 0]$$ y ⋆ ∈ [ - 2.29 , 0 ] is found to be $$\\sigma _{D^{0}}^{y^\\star \\in [-2.29, 0]} = 48.2 \\pm 0.3 \\pm 4.5 \\,\\upmu \\text {b}/\\text {nucleon}$$ σ D 0 y ⋆ ∈ [ - 2.29 , 0 ] = 48.2 ± 0.3 ± 4.5 μ b / nucleon where the first uncertainty is statistical and the second is systematic. The $${{{D}} ^0}-{{\\hspace{0.0pt}\\overline{\\hspace{0.0pt}{D}}} {}^0} $$ D 0 - D ¯ 0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative $$y^{\\star }$$ y ⋆ . The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1 $$\\%$$ % intrinsic charm and 10 $$\\%$$ % recombination contributions better describe the data than the other models considered.
Publisher: American Physical Society (APS)
Date: 08-09-2020
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for William Barter.