ORCID Profile
0000-0003-0875-2533
Current Organisation
University of Amsterdam
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Publisher: American Physical Society (APS)
Date: 20-04-2022
Publisher: American Physical Society (APS)
Date: 25-05-2022
Publisher: Springer Science and Business Media LLC
Date: 2022
Abstract: Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb − 1 collected with the LHCb detector, seven decay modes of the $$ {\\mathrm{B}}_{\\mathrm{c}}^{+} $$ B c + meson into a J / ψ or ψ(2S) meson and three charged hadrons, kaons or pions, are studied. The decays $$ {\\mathrm{B}}_{\\mathrm{c}}^{+} $$ B c + → (ψ(2S) → J / ψπ + π − )π + , $$ {\\mathrm{B}}_{\\mathrm{c}}^{+} $$ B c + → ψ(2S)π + π − π + , $$ {\\mathrm{B}}_{\\mathrm{c}}^{+} $$ B c + → J / ψK + π − π + and $$ {\\mathrm{B}}_{\\mathrm{c}}^{+} $$ B c + → J / ψK + K − K + are observed for the first time, and evidence for the $$ {\\mathrm{B}}_{\\mathrm{c}}^{+} $$ B c + → ψ(2S)K + K − π + , decay is found, where J / ψ and ψ(2S) mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different $$ {\\mathrm{B}}_{\\mathrm{c}}^{+} $$ B c + decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.
Publisher: Springer Science and Business Media LLC
Date: 06-05-2022
Abstract: The $$ {\\varXi}_{cc}^{++}\\to {\\varXi}_c^{\\prime +}{\\pi}^{+} $$ Ξ cc + + → Ξ c ′ + π + decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5 . 4 fb − 1. The $$ {\\varXi}_{cc}^{++}\\to {\\varXi}_c^{\\prime +}{\\pi}^{+} $$ Ξ cc + + → Ξ c ′ + π + decay is reconstructed partially, where the photon from the $$ {\\varXi}_c^{\\prime +}\\to {\\varXi}_c^{+}\\gamma $$ Ξ c ′ + → Ξ c + γ decay is not reconstructed and the pK − π + final state of the $$ {\\varXi}_c^{+} $$ Ξ c + baryon is employed. The $$ {\\varXi}_{cc}^{++}\\to {\\varXi}_c^{\\prime +}{\\pi}^{+} $$ Ξ cc + + → Ξ c ′ + π + branching fraction relative to that of the $$ {\\varXi}_{cc}^{++}\\to {\\varXi}_c^{+}{\\pi}^{+} $$ Ξ cc + + → Ξ c + π + decay is measured to be 1 . 41 ± 0 . 17 ± 0 . 10, where the first uncertainty is statistical and the second systematic.
Publisher: Springer Science and Business Media LLC
Date: 2022
Abstract: The first search for the rare radiative decay $$ {\\Xi}_b^{-} $$ Ξ b − → Ξ − γ is performed using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb − 1 . The $$ {\\Xi}_b^{-} $$ Ξ b − → Ξ − J/ψ channel is used as normalization. No $$ {\\Xi}_b^{-} $$ Ξ b − → Ξ − γ signal is found and an upper limit of $$ \\mathcal{B} $$ B ( $$ {\\Xi}_b^{-} $$ Ξ b − → Ξ − γ ) 1 . 3 × 10 − 4 at 95% confidence level is obtained.
Publisher: American Physical Society (APS)
Date: 24-02-2022
Publisher: American Physical Society (APS)
Date: 25-01-2022
Publisher: Springer Science and Business Media LLC
Date: 10-2020
DOI: 10.1140/EPJC/S10052-020-8365-0
Abstract: A first search for $$CP$$ CP violation in the Cabibbo-suppressed $${{{\\varXi }} ^+_{c}} \\rightarrow {p} {{K} ^-} {{\\pi } ^+} $$ Ξ c + → p K - π + decay is performed using both a binned and an unbinned model-independent technique in the Dalitz plot. The studies are based on a s le of proton-proton collision data, corresponding to an integrated luminosity of $$3.0\\,\\text {fb} ^{-1} $$ 3.0 fb - 1 , and collected by the LHCb experiment at centre-of-mass energies of 7 and $$8\\,\\text {TeV} $$ 8 TeV . The data are consistent with the hypothesis of no $$CP$$ CP violation.
Publisher: IOP Publishing
Date: 05-2022
DOI: 10.1088/1748-0221/17/05/P05009
Abstract: The centrality of heavy-ion collisions is directly related to the created medium in these interactions. A procedure to determine the centrality of collisions with the LHCb detector is implemented for lead-lead collisions at √ s NN = 5 TeV and lead-neon fixed-target collisions at √ s NN = 69 GeV. The energy deposits in the electromagnetic calorimeter are used to determine and define the centrality classes. The correspondence between the number of participants and the centrality for the lead-lead collisions is in good agreement with the correspondence found in other experiments, and the centrality measurements for the lead-neon collisions presented here are performed for the first time in fixed-target collisions at the LHC.
Publisher: American Physical Society (APS)
Date: 16-01-2007
Publisher: American Physical Society (APS)
Date: 21-04-2022
Publisher: American Physical Society (APS)
Date: 12-11-2020
Publisher: Springer Science and Business Media LLC
Date: 03-2021
DOI: 10.1140/EPJC/S10052-021-08994-0
Abstract: Long-lived particles decaying to $${e ^\\pm } {\\mu ^\\mp } {\\nu } $$ e ± μ ∓ ν , with masses between 7 and $$50 \\,\\text {GeV/}c^2 $$ 50 GeV/ c 2 and lifetimes between 2 and $$50 \\,\\text {ps} $$ 50 ps , are searched for by looking at displaced vertices containing electrons and muons of opposite charges. The search is performed using $$5.4 \\,\\text {fb} ^{-1} $$ 5.4 fb - 1 of $$p $$ p $$p $$ p collisions collected with the LHCb detector at a centre-of-mass energy of $$\\sqrt{s} = 13 \\,\\text {TeV} $$ s = 13 TeV . Three mechanisms of production of long-lived particles are considered: the direct pair production from quark interactions, the pair production from the decay of a Standard-Model-like Higgs boson with a mass of $$125 \\,\\text {GeV/}c^2 $$ 125 GeV/ c 2 , and the charged current production from an on-shell $$W $$ W boson with an additional lepton. No evidence of these long-lived states is obtained and upper limits on the production cross-section times branching fraction are set on the different production modes.
Publisher: Springer Science and Business Media LLC
Date: 06-2021
Abstract: Searches for CP violation in the two-body decays $$ {D}_{(s)}^{+}\\to {h}^{+}{\\pi}^0 $$ D s + → h + π 0 and $$ {D}_{(s)}^{+}\\to {h}^{+}\\eta $$ D s + → h + η (where h + denotes a π + or K + meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb − 1 or 6 fb − 1 of integrated luminosity. The π 0 and η mesons are reconstructed using the e + e − γ final state, which can proceed as three-body decays π 0 → e + e − γ and η → e + e − γ , or via the two-body decays π 0 → γγ and η → γγ followed by a photon conversion. The measurements are made relative to the control modes $$ {D}_{(s)}^{+}\\to {K}_{\\mathrm{S}}^0{h}^{+} $$ D s + → K S 0 h + to cancel the production and detection asymmetries. The CP asymmetries are measured to be $$ {\\displaystyle \\begin{array}{c}{\\mathcal{A}}_{CP}\\left({D}^{+}\\to {\\pi}^{+}{\\pi}^0\\right)=\\left(-1.3\\pm 0.9\\pm 0.6\\right)\\%,\\\\ {}{\\mathcal{A}}_{CP}\\left({D}^{+}\\to {K}^{+}{\\pi}^0\\right)=\\left(-3.2\\pm 4.7\\pm 2.1\\right)\\%,\\\\ {}\\begin{array}{c}{\\mathcal{A}}_{CP}\\left({D}^{+}\\to {\\pi}^{+}\\eta \\right)=\\left(-0.2\\pm 0.8\\pm 0.4\\right)\\%,\\\\ {}{\\mathcal{A}}_{CP}\\left({D}^{+}\\to {K}^{+}\\eta \\right)=\\left(-6\\pm 10\\pm 4\\right)\\%,\\\\ {}\\begin{array}{c}{\\mathcal{A}}_{CP}\\left({D}_s^{+}\\to {K}^{+}{\\pi}^0\\right)=\\left(-0.8\\pm 3.9\\pm 1.2\\right)\\%,\\\\ {}\\begin{array}{c}{\\mathcal{A}}_{CP}\\left({D}_s^{+}\\to {\\pi}^{+}\\eta \\right)=\\left(0.8\\pm 0.7\\pm 0.5\\right)\\%,\\\\ {}{\\mathcal{A}}_{CP}\\left({D}_s^{+}\\to {K}^{+}\\eta \\right)=\\left(0.9\\pm 3.7\\pm 1.1\\right)\\%,\\end{array}\\end{array}\\end{array}\\end{array}} $$ A CP D + → π + π 0 = − 1.3 ± 0.9 ± 0.6 % , A CP D + → K + π 0 = − 3.2 ± 4.7 ± 2.1 % , A CP D + → π + η = − 0.2 ± 0.8 ± 0.4 % , A CP D + → K + η = − 6 ± 10 ± 4 % , A CP D s + → K + π 0 = − 0.8 ± 3.9 ± 1.2 % , A CP D s + → π + η = 0.8 ± 0.7 ± 0.5 % , A CP D s + → K + η = 0.9 ± 3.7 ± 1.1 % , where the first uncertainties are statistical and the second systematic. These results are consistent with no CP violation and mostly constitute the most precise measurements of $$ {\\mathcal{A}}_{CP} $$ A CP in these decay modes to date.
Publisher: Springer Science and Business Media LLC
Date: 11-2021
Abstract: An angular analysis of the rare decay $$ {B}_s^0 $$ B s 0 → ϕμ + μ − is presented, using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 8.4 fb − 1 . The observables describing the angular distributions of the decay $$ {B}_s^0 $$ B s 0 → ϕμ + μ − are determined in regions of q 2 , the square of the dimuon invariant mass. The results are consistent with Standard Model predictions.
Publisher: Springer Science and Business Media LLC
Date: 02-2021
Abstract: The decays $$ {\\mathrm{B}}_{\\mathrm{s}}^0 $$ B s 0 → J / ψπ + π − K + K − are studied using a data set corresponding to an integrated luminosity of 9 fb − 1 , collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The decays $$ {\\mathrm{B}}_{\\mathrm{s}}^0 $$ B s 0 → $$ \\mathrm{J}/{\\uppsi \\mathrm{K}}^{\\ast 0}{\\overline{\\mathrm{K}}}^{\\ast 0} $$ J / ψK ∗ 0 K ¯ ∗ 0 and $$ {\\mathrm{B}}_{\\mathrm{s}}^0 $$ B s 0 → χ c1 (3872)K + K − , where the K + K − pair does not originate from a ϕ meson, are observed for the first time. Precise measurements of the ratios of branching fractions between intermediate χ c1 (3872)ϕ, $$ \\mathrm{J}/{\\uppsi \\mathrm{K}}^{\\ast 0}{\\overline{\\mathrm{K}}}^{\\ast 0} $$ J / ψK ∗ 0 K ¯ ∗ 0 , ψ(2S)ϕ and χ c1 (3872)K + K − states are reported. A structure, denoted as X(4740), is observed in the J / ψϕ mass spectrum and, assuming a Breit-Wigner parameterisation, its mass and width are determined to be $$ {\\displaystyle \\begin{array}{c}{m}_{\\mathrm{X}(4740)}=4741\\pm 6\\pm 6\\kern0.5em \\mathrm{MeV}/{c}^2,\\\\ {}{\\Gamma}_{\\mathrm{X}(4740)}=53\\pm 15\\pm 11\\kern0.5em \\mathrm{MeV},\\end{array}} $$ m X 4740 = 4741 ± 6 ± 6 MeV / c 2 , Γ X 4740 = 53 ± 15 ± 11 MeV , where the first uncertainty is statistical and the second is systematic. In addition, the most precise single measurement of the mass of the $$ {\\mathrm{B}}_{\\mathrm{s}}^0 $$ B s 0 meson is performed and gives a value of $$ {m}_{{\\mathrm{B}}_{\\mathrm{s}}^0}=5366.98\\pm 0.07\\pm 0.13\\kern0.5em \\mathrm{MeV}/{c}^2. $$ m B s 0 = 5366.98 ± 0.07 ± 0.13 MeV / c 2 .
Publisher: American Physical Society (APS)
Date: 17-08-2021
Publisher: Springer Science and Business Media LLC
Date: 02-2021
Abstract: The inclusive $$ b\\overline{b} $$ b b ¯ - and $$ c\\overline{c} $$ c c ¯ -dijet production cross-sections in the forward region of pp collisions are measured using a data s le collected with the LHCb detector at a centre-of-mass energy of 13 TeV in 2016. The data s le corresponds to an integrated luminosity of 1.6 fb − 1 . Differential cross-sections are measured as a function of the transverse momentum and of the pseudorapidity of the leading jet, of the rapidity difference between the jets, and of the dijet invariant mass. A fiducial region for the measurement is defined by requiring that the two jets originating from the two b or c quarks are emitted with transverse momentum greater than 20 GeV/ c , pseudorapidity in the range 2 . 2 η 4 . 2, and with a difference in the azimuthal angle between the two jets greater than 1.5. The integrated $$ b\\overline{b} $$ b b ¯ -dijet cross-section is measured to be 53 . 0 ± 9 . 7 nb, and the total $$ c\\overline{c} $$ c c ¯ -dijet cross-section is measured to be 73 ± 16 nb. The ratio between $$ c\\overline{c} $$ c c ¯ - and $$ b\\overline{b} $$ b b ¯ -dijet cross-sections is also measured and found to be 1 . 37 ± 0 . 27. The results are in agreement with theoretical predictions at next-to-leading order.
Publisher: American Physical Society (APS)
Date: 07-02-2022
Publisher: IOP Publishing
Date: 02-2022
DOI: 10.1088/1748-0221/17/02/P02028
Abstract: The identification of charm jets is achieved at LHCb for data collected in 2015–2018 using a method based on the properties of displaced vertices reconstructed and matched with jets. The performance of this method is determined using a dijet calibration dataset recorded by the LHCb detector and selected such that the jets are unbiased in quantities used in the tagging algorithm. The charm-tagging efficiency is reported as a function of the transverse momentum of the jet. The measured efficiencies are compared to those obtained from simulation and found to be in good agreement.
Publisher: arXiv
Date: 2021
Publisher: American Physical Society (APS)
Date: 20-08-2021
Publisher: arXiv
Date: 2021
Publisher: arXiv
Date: 2021
Publisher: American Physical Society (APS)
Date: 20-02-2020
Publisher: American Physical Society (APS)
Date: 07-12-2020
Publisher: American Physical Society (APS)
Date: 20-11-2020
Publisher: American Physical Society (APS)
Date: 22-04-2021
Publisher: Springer Science and Business Media LLC
Date: 12-2021
Abstract: A combination of measurements sensitive to the CP violation angle γ of the Cabibbo-Kobayashi-Maskawa unitarity triangle and to the charm mixing parameters that describe oscillations between D 0 and $$ \\overline{D} $$ D ¯ 0 mesons is performed. Results from the charm and beauty sectors, based on data collected with the LHCb detector at CERN’s Large Hadron Collider, are combined for the first time. This method provides an improvement on the precision of the charm mixing parameter y by a factor of two with respect to the current world average. The charm mixing parameters are determined to be $$ x=\\left({0.400}_{-0.053}^{+0.052}\\right)\\% $$ x = 0.400 − 0.053 + 0.052 % and y = $$ \\left({0.630}_{-0.030}^{+0.033}\\right)\\% $$ 0.630 − 0.030 + 0.033 % . The angle γ is found to be γ = $$ \\left({65.4}_{-4.2}^{+3.8}\\right){}^{\\circ} $$ 65.4 − 4.2 + 3.8 ° and is the most precise determination from a single experiment.
Publisher: Springer Science and Business Media LLC
Date: 08-04-2022
Abstract: A study of B + → J / ψηK + decays, followed by J / ψ → μ + μ − and η → γγ, is performed using a dataset collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb − 1 . The J / ψη mass spectrum is investigated for contributions from charmonia and charmonium-like states. Evidence is found for the B + → (ψ 2 (3823) → J / ψη)K + and B + → (ψ(4040) → J / ψη)K + decays with significance of 3.4 and 4.7 standard deviations, respectively. This constitutes the first evidence for the ψ 2 (3823) → J / ψη decay.
Publisher: Springer Science and Business Media LLC
Date: 08-2020
Abstract: The decays B + → J / ψπ + π − K + are studied using a data set corresponding to an integrated luminosity of 9 fb − 1 collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ 2 (3823), χ c1 (3872) and ψ(2S) states are reported. The values are $$ {\\displaystyle \\begin{array}{c}\\frac{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to {\\uppsi}_2(3823){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\uppsi_2(3823)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to {\\upchi}_{\\mathrm{c}1}(3872){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\upchi_{\\mathrm{c}1}(3872)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}=\\left(3.56\\pm 0.67\\pm 0.11\\right)\\times {10}^{-2},\\\\ {}\\frac{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to {\\uppsi}_2(3823){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\uppsi_2(3823)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to \\uppsi \\left(2\\mathrm{S}\\right){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\uppsi \\left(2\\mathrm{S}\\right)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}=\\left(1.31\\pm 0.25\\pm 0.04\\right)\\times {10}^{-3},\\\\ {}\\frac{{\\mathcal{B}}_{\\mathrm{B}+\\to {\\upchi}_{\\mathrm{c}1}(3872){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\upchi_{\\mathrm{c}1}(3872)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to \\uppsi \\left(2\\mathrm{S}\\right){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\uppsi \\left(2\\mathrm{S}\\right)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}=\\left(3.69\\pm 0.07\\pm 0.06\\right)\\times {10}^{-2},\\end{array}} $$ B B + → ψ 2 3823 K + × B ψ 2 3823 → J / ψπ + π − B B + → χ c 1 3872 K + × B χ c 1 3872 → J / ψπ + π − = 3.56 ± 0.67 ± 0.11 × 10 − 2 , B B + → ψ 2 3823 K + × B ψ 2 3823 → J / ψπ + π − B B + → ψ 2 S K + × B ψ 2 S → J / ψπ + π − = 1.31 ± 0.25 ± 0.04 × 10 − 3 , B B + → χ c 1 3872 K + × B χ c 1 3872 → J / ψπ + π − B B + → ψ 2 S K + × B ψ 2 S → J / ψπ + π − = 3.69 ± 0.07 ± 0.06 × 10 − 2 , where the first uncertainty is statistical and the second is systematic. The decay of B + → ψ 2 (3823)K + with ψ 2 (3823) → J / ψπ + π − is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ 2 (3823), χ c1 (3872) and ψ(2S) states are measured to be $$ {\\displaystyle \\begin{array}{c}{m}_{\\upchi_{\\mathrm{c}1}(3872)}-{m}_{\\uppsi_2(3823)}=47.50\\pm 0.53\\pm 0.13\\ \\mathrm{MeV}/{c}^2,\\\\ {}{m}_{\\uppsi_2(3823)}-{m}_{\\uppsi_2\\left(2\\mathrm{S}\\right)}=137.98\\pm 0.53\\pm 0.14\\ \\mathrm{MeV}/{c}^2,\\\\ {}{m}_{\\upchi_{\\mathrm{c}1}(3872)}-{m}_{\\uppsi_2\\left(2\\mathrm{S}\\right)}=185.49\\pm 0.06\\pm 0.03\\ \\mathrm{MeV}/{c}^2,\\end{array}} $$ m χ c 1 3872 − m ψ 2 3823 = 47.50 ± 0.53 ± 0.13 MeV / c 2 , m ψ 2 3823 − m ψ 2 2 S = 137.98 ± 0.53 ± 0.14 MeV / c 2 , m χ c 1 3872 − m ψ 2 2 S = 185.49 ± 0.06 ± 0.03 MeV / c 2 , resulting in the most precise determination of the χ c1 (3872) mass. The width of the ψ 2 (3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χ c1 (3872) state is measured to be $$ {\\Gamma}_{\\upchi_{\\mathrm{c}1}(3872)}^{\\mathrm{BW}}={0.96}_{-0.18}^{+0.19}\\pm 0.21\\ \\mathrm{MeV} $$ Γ χ c 1 3872 BW = 0.96 − 0.18 + 0.19 ± 0.21 MeV which is inconsistent with zero by 5.5 standard deviations.
Publisher: Springer Science and Business Media LLC
Date: 12-2020
Abstract: A measurement of four branching-fraction ratios for three-body decays of B mesons involving two open-charm hadrons in the final state is presented. Run 1 and Run 2 pp collision data are used, recorded by the LHCb experiment at centre-of-mass energies 7, 8, and 13 TeV and corresponding to an integrated luminosity of 9 fb − 1 . The measured branching-fraction ratios are $$ {\\displaystyle \\begin{array}{c}\\frac{\\mathcal{B}\\left({B}^{+}\\to {D}^{\\ast +}{D}^{-}{K}^{+}\\right)}{\\mathcal{B}\\left({B}^{+}\\to {\\overline{D}}^0{D}^0{K}^{+}\\right)}=0.517\\pm 0.015\\pm 0.013\\pm 0.011,\\\\ {}\\frac{\\mathcal{B}\\left({B}^{+}\\to {D}^{\\ast -}{D}^{+}{K}^{+}\\right)}{\\mathcal{B}\\left({B}^{+}\\to {\\overline{D}}^0{D}^0{K}^{+}\\right)}=0.577\\pm 0.016\\pm 0.013\\pm 0.013,\\\\ {}\\begin{array}{c}\\frac{\\mathcal{B}\\left({B}^0\\to {D}^{\\ast -}{D}^0{K}^{+}\\right)}{\\mathcal{B}\\left({B}^0\\to {D}^{-}{D}^0{K}^{+}\\right)}=1.754\\pm 0.028\\pm 0.016\\pm 0.035,\\\\ {}\\frac{\\mathcal{B}\\left({B}^{+}\\to {D}^{\\ast +}{D}^{-}{K}^{+}\\right)}{\\mathcal{B}\\left({B}^{+}\\to {D}^{\\ast -}{D}^{+}{K}^{+}\\right)}=0.907\\pm 0.033\\pm 0.014,\\end{array}\\end{array}} $$ B B + → D ∗ + D − K + B B + → D ¯ 0 D 0 K + = 0.517 ± 0.015 ± 0.013 ± 0.011 , B B + → D ∗ − D + K + B B + → D ¯ 0 D 0 K + = 0.577 ± 0.016 ± 0.013 ± 0.013 , B B 0 → D ∗ − D 0 K + B B 0 → D − D 0 K + = 1.754 ± 0.028 ± 0.016 ± 0.035 , B B + → D ∗ + D − K + B B + → D ∗ − D + K + = 0.907 ± 0.033 ± 0.014 , where the first of the uncertainties is statistical, the second systematic, and the third is due to the uncertainties on the D -meson branching fractions. These are the most accurate measurements of these ratios to date.
Publisher: Springer Science and Business Media LLC
Date: 18-04-2023
Abstract: Searches for CP violation in the decays $$ {D}_{(s)}^{+}\\to \\eta {\\pi}^{+} $$ D s + → η π + and $$ {D}_{(s)}^{+}\\to {\\eta}^{\\prime }{\\pi}^{+} $$ D s + → η ′ π + are performed using pp collision data corresponding to 6 fb − 1 of integrated luminosity collected by the LHCb experiment. The calibration channels $$ {D}_{(s)}^{+}\\to \\phi {\\pi}^{+} $$ D s + → ϕ π + are used to remove production and detection asymmetries. The resulting CP -violating asymmetries are $$ {\\displaystyle \\begin{array}{l}{\\mathcal{A}}^{CP}=\\left({D}^{+}\\to \\eta {\\pi}^{+}\\right)=\\left(0.34\\pm 0.66\\pm 0.16\\pm 0.05\\right)\\%,\\\\ {}{\\mathcal{A}}^{CP}=\\left({D}_s^{+}\\to \\eta {\\pi}^{+}\\right)=\\left(0.32\\pm 0.51\\pm 0.12\\right)\\%,\\\\ {}\\begin{array}{l}{\\mathcal{A}}^{CP}=\\left({D}^{+}\\to {\\eta}^{\\prime }{\\pi}^{+}\\right)=\\left(0.49\\pm 0.18\\pm 0.06\\pm 0.05\\right)\\%,\\\\ {}{\\mathcal{A}}^{CP}=\\left({D}_s^{+}\\to {\\eta}^{\\prime }{\\pi}^{+}\\right)=\\left(0.01\\pm 0.12\\pm 0.08\\right)\\%,\\end{array}\\end{array}} $$ A CP = D + → η π + = 0.34 ± 0.66 ± 0.16 ± 0.05 % , A CP = D s + → η π + = 0.32 ± 0.51 ± 0.12 % , A CP = D + → η ′ π + = 0.49 ± 0.18 ± 0.06 ± 0.05 % , A CP = D s + → η ′ π + = 0.01 ± 0.12 ± 0.08 % , where the first uncertainty is statistical, the second is systematic and the third, relevant for the D + channels, is due to the uncertainty on $$ {\\mathcal{A}}^{CP}=\\left({D}^{+}\\to \\phi {\\pi}^{+}\\right) $$ A CP = D + → ϕ π + . These measurements, currently the most precise for three of the four channels considered, are consistent with the absence of CP violation. A combination of these results with previous LHCb measurements is presented.
Publisher: American Physical Society (APS)
Date: 02-03-2021
Publisher: American Physical Society (APS)
Date: 26-03-2021
Publisher: American Physical Society (APS)
Date: 27-08-2021
Publisher: Springer Science and Business Media LLC
Date: 2022
DOI: 10.1038/S41567-021-01394-X
Abstract: Mesons comprising a beauty quark and strange quark can oscillate between particle ( $${B}_{\\mathrm{s}}^{0}$$ B s 0 ) and antiparticle ( $${\\overline{B}}_{\\mathrm{s}}^{0}$$ B ¯ s 0 ) flavour eigenstates, with a frequency given by the mass difference between heavy and light mass eigenstates, Δ m s . Here we present a measurement of Δ m s using $${B}_{\\mathrm{s}}^{0}\\to {D}_{\\mathrm{s}}^{-}$$ B s 0 → D s − π + decays produced in proton–proton collisions collected with the LHCb detector at the Large Hadron Collider. The oscillation frequency is found to be Δ m s = 17.7683 ± 0.0051 ± 0.0032 ps −1 , where the first uncertainty is statistical and the second is systematic. This measurement improves on the current Δ m s precision by a factor of two. We combine this result with previous LHCb measurements to determine Δ m s = 17.7656 ± 0.0057 ps −1 , which is the legacy measurement of the original LHCb detector.
Publisher: Springer Science and Business Media LLC
Date: 11-2021
Abstract: The production cross-sections of J/ψ mesons in proton-proton collisions at a centre-of-mass energy of $$ \\sqrt{s} $$ s = 5 TeV are measured using a data s le corresponding to an integrated luminosity of 9 . 13 ± 0 . 18 pb − 1 , collected by the LHCb experiment. The cross-sections are measured differentially as a function of transverse momentum, p T , and rapidity, y , and separately for J/ψ mesons produced promptly and from beauty hadron decays (nonprompt). With the assumption of unpolarised J/ψ mesons, the production cross-sections integrated over the kinematic range 0 p T 20 GeV/ c and 2 . 0 y 4 . 5 are $$ {\\displaystyle \\begin{array}{c}{\\sigma}_{\\mathrm{prompt}}\\ J/\\psi =8.154\\pm 0.010\\pm 0.283\\ \\upmu \\mathrm{b},\\\\ {}{\\sigma}_{\\mathrm{nonprompt}}\\ J/\\psi =0.820\\pm 0.003\\pm 0.034\\ \\upmu \\mathrm{b},\\end{array}} $$ σ prompt J / ψ = 8.154 ± 0.010 ± 0.283 μb , σ nonprompt J / ψ = 0.820 ± 0.003 ± 0.034 μb , where the first uncertainties are statistical and the second systematic. These cross-sections are compared with those at $$ \\sqrt{s} $$ s = 8 TeV and 13 TeV, and are used to update the measurement of the nuclear modification factor in proton-lead collisions for J/ψ mesons at a centre-of-mass energy per nucleon pair of $$ \\sqrt{s_{\\mathrm{NN}}} $$ s NN = 5 TeV. The results are compared with theoretical predictions.
Publisher: American Physical Society (APS)
Date: 22-12-2020
Publisher: American Physical Society (APS)
Date: 18-12-2020
Publisher: American Astronomical Society
Date: 05-2023
Abstract: Core-collapse supernovae are a promising potential high-energy neutrino source class. We test for correlation between seven years of IceCube neutrino data and a catalog containing more than 1000 core-collapse supernovae of types IIn and IIP and a s le of stripped-envelope supernovae. We search both for neutrino emission from in idual supernovae as well as for combined emission from the whole supernova s le, through a stacking analysis. No significant spatial or temporal correlation of neutrinos with the cataloged supernovae was found. All scenarios were tested against the background expectation and together yield an overall p -value of 93% therefore, they show consistency with the background only. The derived upper limits on the total energy emitted in neutrinos are 1.7 × 10 48 erg for stripped-envelope supernovae, 2.8 × 10 48 erg for type IIP, and 1.3 × 10 49 erg for type IIn SNe, the latter disfavoring models with optimistic assumptions for neutrino production in interacting supernovae. We conclude that stripped-envelope supernovae and supernovae of type IIn do not contribute more than 14.6% and 33.9%, respectively, to the diffuse neutrino flux in the energy range of about [ 10 3 –10 5 ] GeV, assuming that the neutrino energy spectrum follows a power-law with an index of −2.5. Under the same assumption, we can only constrain the contribution of type IIP SNe to no more than 59.9%. Thus, core-collapse supernovae of types IIn and stripped-envelope supernovae can both be ruled out as the dominant source of the diffuse neutrino flux under the given assumptions.
Publisher: American Astronomical Society
Date: 10-2022
Abstract: The majority of astrophysical neutrinos have undetermined origins. The IceCube Neutrino Observatory has observed astrophysical neutrinos but has not yet identified their sources. Blazars are promising source candidates, but previous searches for neutrino emission from populations of blazars detected in ≳GeV gamma rays have not observed any significant neutrino excess. Recent findings in multimessenger astronomy indicate that high-energy photons, coproduced with high-energy neutrinos, are likely to be absorbed and reemitted at lower energies. Thus, lower-energy photons may be better indicators of TeV–PeV neutrino production. This paper presents the first time-integrated stacking search for astrophysical neutrino emission from MeV-detected blazars in the first Fermi Large Area Telescope low energy (1FLE) catalog using ten years of IceCube muon–neutrino data. The results of this analysis are found to be consistent with a background-only hypothesis. Assuming an E −2 neutrino spectrum and proportionality between the blazars MeV gamma-ray fluxes and TeV–PeV neutrino flux, the upper limit on the 1FLE blazar energy-scaled neutrino flux is determined to be 1.64 × 10 −12 TeV cm −2 s −1 at 90% confidence level. This upper limit is approximately 1% of IceCube’s diffuse muon–neutrino flux measurement.
Publisher: American Astronomical Society
Date: 11-2022
Abstract: Gamma-ray bursts (GRBs) are considered as promising sources of ultra-high-energy cosmic rays (UHECRs) due to their large power output. Observing a neutrino flux from GRBs would offer evidence that GRBs are hadronic accelerators of UHECRs. Previous IceCube analyses, which primarily focused on neutrinos arriving in temporal coincidence with the prompt gamma-rays, found no significant neutrino excess. The four analyses presented in this paper extend the region of interest to 14 days before and after the prompt phase, including generic extended time windows and targeted precursor searches. GRBs were selected between 2011 May and 2018 October to align with the data set of candidate muon-neutrino events observed by IceCube. No evidence of correlation between neutrino events and GRBs was found in these analyses. Limits are set to constrain the contribution of the cosmic GRB population to the diffuse astrophysical neutrino flux observed by IceCube. Prompt neutrino emission from GRBs is limited to ≲1% of the observed diffuse neutrino flux, and emission on timescales up to 10 4 s is constrained to 24% of the total diffuse flux.
Publisher: American Physical Society (APS)
Date: 25-01-2022
Publisher: American Physical Society (APS)
Date: 11-05-2022
Publisher: American Astronomical Society
Date: 04-2023
Abstract: This paper presents the results of a search for neutrinos that are spatially and temporally coincident with 22 unique, nonrepeating fast radio bursts (FRBs) and one repeating FRB (FRB 121102). FRBs are a rapidly growing class of Galactic and extragalactic astrophysical objects that are considered a potential source of high-energy neutrinos. The IceCube Neutrino Observatory’s previous FRB analyses have solely used track events. This search utilizes seven years of IceCube cascade events which are statistically independent of track events. This event selection allows probing of a longer range of extended timescales due to the low background rate. No statistically significant clustering of neutrinos was observed. Upper limits are set on the time-integrated neutrino flux emitted by FRBs for a range of extended time windows.
Publisher: American Physical Society (APS)
Date: 13-05-2022
Publisher: Springer Science and Business Media LLC
Date: 12-2020
Abstract: An angular analysis of the B 0 → K* 0 e + e − decay is performed using a data s le corresponding to an integrated luminosity of 9 fb − 1 of pp collisions collected with the LHCb experiment. The analysis is conducted in the very low dielectron mass squared ( q 2 ) interval between 0 . 0008 and 0 . 257 GeV 2 , where the rate is dominated by the B 0 → K * 0 γ transition with a virtual photon. The fraction of longitudinal polarisation of the K * 0 meson, F L , is measured to be F L = (4 . 4 ± 2 . 6 ± 1 . 4)%, where the first uncertainty is statistical and the second systematic. The $$ {A}_{\\mathrm{T}}^{\\mathrm{Re}} $$ A T Re observable, which is related to the lepton forward-backward asymmetry, is measured to be $$ {A}_{\\mathrm{T}}^{\\mathrm{Re}} $$ A T Re = − 0 . 06 ± 0 . 08 ± 0 . 02. The $$ {A}_{\\mathrm{T}}^{(2)} $$ A T 2 and $$ {A}_{\\mathrm{T}}^{\\mathrm{Im}} $$ A T Im transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be $$ {A}_{\\mathrm{T}}^{(2)} $$ A T 2 = 0 . 11 ± 0 . 10 ± 0 . 02 and $$ {A}_{\\mathrm{T}}^{\\mathrm{Im}} $$ A T Im = 0 . 02 ± 0 . 10 ± 0 . 01. The results are consistent with Standard Model predictions and provide the world’s best constraint on the b → sγ photon polarisation.
Publisher: American Physical Society (APS)
Date: 05-10-2021
Publisher: American Physical Society (APS)
Date: 22-09-2020
Publisher: arXiv
Date: 2022
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: 06-2021
Abstract: A search is performed for rare and forbidden charm decays of the form $$ {D}_{(s)}^{+}\\to {h}^{\\pm }{\\mathrm{\\ell}}^{+}{\\mathrm{\\ell}}^{\\left(\\prime \\right)\\mp } $$ D s + → h ± ℓ + ℓ ′ ∓ , where h ± is a pion or kaon and ℓ (′)± is an electron or muon. The measurements are performed using proton-proton collision data, corresponding to an integrated luminosity of 1 . 6 fb − 1 , collected by the LHCb experiment in 2016. No evidence is observed for the 25 decay modes that are investigated and 90 % confidence level limits on the branching fractions are set between 1 . 4 × 10 − 8 and 6 . 4 × 10 − 6 . In most cases, these results represent an improvement on existing limits by one to two orders of magnitude.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Springer Science and Business Media LLC
Date: 03-2021
DOI: 10.1140/EPJC/S10052-021-08973-5
Abstract: A search is performed for heavy neutrinos in the decay of a W boson into two muons and a jet. The data set corresponds to an integrated luminosity of approximately $$3.0\\, \\text {fb} ^{-1} $$ 3.0 fb - 1 of proton–proton collision data at centre-of-mass energies of 7 and $$8\\, \\text {TeV} $$ 8 TeV collected with the LHCb experiment. Both same-sign and opposite-sign muons in the final state are considered. Data are found to be consistent with the expected background. Upper limits on the coupling of a heavy neutrino with the Standard Model neutrino are set at $$95\\%$$ 95 % confidence level in the heavy-neutrino mass range from 5 to $$50\\, \\text {GeV/}c^2 $$ 50 GeV/ c 2 . These are of the order of $$10^{-3}$$ 10 - 3 for lepton-number-conserving decays and of the order of $$10^{-4}$$ 10 - 4 for lepton-number-violating heavy-neutrino decays.
Publisher: American Physical Society (APS)
Date: 09-06-2021
Publisher: American Astronomical Society
Date: 08-2022
Abstract: For several decades, the origin of ultra-high-energy cosmic rays (UHECRs) has been an unsolved question of high-energy astrophysics. One approach for solving this puzzle is to correlate UHECRs with high-energy neutrinos, since neutrinos are a direct probe of hadronic interactions of cosmic rays and are not deflected by magnetic fields. In this paper, we present three different approaches for correlating the arrival directions of neutrinos with the arrival directions of UHECRs. The neutrino data are provided by the IceCube Neutrino Observatory and ANTARES, while the UHECR data with energies above ∼50 EeV are provided by the Pierre Auger Observatory and the Telescope Array. All experiments provide increased statistics and improved reconstructions with respect to our previous results reported in 2015. The first analysis uses a high-statistics neutrino s le optimized for point-source searches to search for excesses of neutrino clustering in the vicinity of UHECR directions. The second analysis searches for an excess of UHECRs in the direction of the highest-energy neutrinos. The third analysis searches for an excess of pairs of UHECRs and highest-energy neutrinos on different angular scales. None of the analyses have found a significant excess, and previously reported overfluctuations are reduced in significance. Based on these results, we further constrain the neutrino flux spatially correlated with UHECRs.
Publisher: American Physical Society (APS)
Date: 12-10-2020
Publisher: arXiv
Date: 2022
Publisher: Springer Science and Business Media LLC
Date: 07-2022
Abstract: A data s le collected with the LHCb detector corresponding to an integrated luminosity of 9 fb − 1 is used to measure eleven CP violation observables in B ± → Dh ± decays, where h is either a kaon or a pion. The neutral D meson decay is reconstructed in the three-body final states: K ± π ∓ π 0 π + π − π 0 K + K − π 0 and the suppressed π ± K ∓ π 0 combination. The mode where a large CP asymmetry is expected, B ± → [ π ± K ∓ π 0 ] D K ± , is observed with a significance greater than seven standard deviations. The ratio of the partial width of this mode relative to that of the favoured mode, B ± → [ K ± π ∓ π 0 ] D K ± , is R ADS( K ) = (1 . 27 ± 0 . 16 ± 0 . 02) × 10 − 2 . Evidence for a large CP asymmetry is also seen: A ADS( K ) = −0 . 38 ± 0 . 12 ± 0 . 02. Constraints on the CKM angle γ are calculated from the eleven reported observables.
Publisher: Springer Science and Business Media LLC
Date: 09-06-2023
Abstract: An litude analysis of the D + → π − π + π + decay is performed with a s le corresponding to 1.5 fb − 1 of integrated luminosity of pp collisions at a centre-of-mass energy $$ \\sqrt{s} $$ s = 8 TeV collected by the LHCb detector in 2012. The s le contains approximately six hundred thousand candidates with a signal purity of 95%. The resonant structure is studied through a fit to the Dalitz plot where the π − π + S-wave litude is extracted as a function of π − π + mass, and spin-1 and spin-2 resonances are included coherently through an isobar model. The S-wave component is found to be dominant, followed by the ρ (770) 0 π + and f 2 (1270) π + components. A small contribution from the ω (782) → π − π + decay is seen for the first time in the D + → π − π + π + decay.
Publisher: Springer Science and Business Media LLC
Date: 2022
Abstract: The production cross-section of the χ c 1 (3872) state relative to the ψ (2 S ) meson is measured using proton-proton collision data collected with the LHCb experiment at centre-of-mass energies of $$ \\sqrt{s} $$ s = 8 and 13 TeV, corresponding to integrated luminosities of 2.0 and 5.4 fb − 1 , respectively. The two mesons are reconstructed in the J/ψπ + π − final state. The ratios of the prompt and nonprompt χ c 1 (3872) to ψ (2 S ) production cross-sections are measured as a function of transverse momentum, p T , and rapidity, y , of the χ c 1 (3872) and ψ (2 S ) states, in the kinematic range 4 p T 20 GeV/ c and 2 . 0 y 4 . 5. The prompt ratio is found to increase with p T , independently of y . For the prompt component, the double ratio of the χ c 1 (3872) and ψ (2 S ) production cross-sections between 13 and 8 TeV is observed to be consistent with unity, independent of p T and centre-of-mass energy.
Publisher: Springer Science and Business Media LLC
Date: 16-06-2022
DOI: 10.1038/S41567-022-01614-Y
Abstract: Conventional, hadronic matter consists of baryons and mesons made of three quarks and a quark–antiquark pair, respectively 1,2 . Here, we report the observation of a hadronic state containing four quarks in the Large Hadron Collider beauty experiment. This so-called tetraquark contains two charm quarks, a $$\\overline{{{{{u}}}}}$$ u ¯ and a $$\\overline{{{{{d}}}}}$$ d ¯ quark. This exotic state has a mass of approximately 3,875 MeV and manifests as a narrow peak in the mass spectrum of D 0 D 0 π + mesons just below the D *+ D 0 mass threshold. The near-threshold mass together with the narrow width reveals the resonance nature of the state.
Publisher: American Physical Society (APS)
Date: 02-12-2020
Publisher: Springer Science and Business Media LLC
Date: 03-2021
Abstract: The time-dependent CP asymmetries of B 0 → π + π − and $$ {B}_s^0 $$ B s 0 → K + K − decays are measured using a data s le of pp collisions corresponding to an integrated luminosity of 1.9 fb − 1 , collected with the LHCb detector at a centre-of-mass energy of 13 TeV. The results are $$ {\\displaystyle \\begin{array}{c}{C}_{\\pi \\pi}=-0.311\\pm 0.045\\pm 0.015,\\\\ {}{S}_{\\pi \\pi}=-0.706\\pm 0.042\\pm 0.013,\\\\ {}{C}_{KK}=0.123\\pm 0.034\\pm 0.015,\\\\ {}{S}_{KK}=0.164\\pm 0.034\\pm 0.014,\\\\ {}{\\mathcal{A}}_{KK}^{\\Delta \\varGamma }=-0.83\\pm 0.05\\pm 0.09,\\end{array}} $$ C ππ = − 0.311 ± 0.045 ± 0.015 , S ππ = − 0.706 ± 0.042 ± 0.013 , C KK = 0.123 ± 0.034 ± 0.015 , S KK = 0.164 ± 0.034 ± 0.014 , A KK Δ Γ = − 0.83 ± 0.05 ± 0.09 , where the first uncertainties are statistical and the second systematic. The same data s le is used to measure the time-integrated CP asymmetries of B 0 → K + π − and $$ {B}_s^0 $$ B s 0 → K − π + decays and the results are $$ {\\displaystyle \\begin{array}{c}{A}_{CP}^{B^0}=-0.0824\\pm 0.0033\\pm 0.0033,\\\\ {}{A}_{CP}^{B_s^0}=0.236\\pm 0.013\\pm 0.011.\\end{array}} $$ A CP B 0 = − 0.0824 ± 0.0033 ± 0.0033 , A CP B s 0 = 0.236 ± 0.013 ± 0.011 . All results are consistent with earlier measurements. A combination of LHCb measurements provides the first observation of time-dependent CP violation in $$ {B}_s^0 $$ B s 0 decays.
Publisher: Springer Science and Business Media LLC
Date: 06-2021
Abstract: The first full angular analysis of the $$ {B}^0\\to {D}^{\\ast -}{D}_s^{\\ast +} $$ B 0 → D ∗ − D s ∗ + decay is performed using 6 fb − 1 of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The $$ {D}_s^{\\ast +}\\to {D}_s^{+}\\gamma $$ D s ∗ + → D s + γ and D * − → $$ {\\overline{D}}^0{\\pi}^{-} $$ D ¯ 0 π − vector meson decays are used with the subsequent $$ {D}_s^{+} $$ D s + → K + K − π + and $$ {\\overline{D}}^0 $$ D ¯ 0 → K + π − decays. All helicity litudes and phases are measured, and the longitudinal polarisation fraction is determined to be f L = 0 . 578 ± 0 . 010 ± 0 . 011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity litude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [ℬ( $$ {B}^0\\to {D}^{\\ast -}{D}_s^{\\ast +} $$ B 0 → D ∗ − D s ∗ + ) × ℬ( $$ {D}_s^{\\ast +}\\to {D}_s^{+}\\gamma $$ D s ∗ + → D s + γ )] / ℬ( B 0 → D * − $$ {D}_s^{+} $$ D s + ) is measured to be 2 . 045 ± 0 . 022 ± 0 . 071 with world-best precision. In addition, the first observation of the Cabibbo-suppressed B s → D * − $$ {D}_s^{+} $$ D s + decay is made with a significance of seven standard deviations. The branching fraction ratio ℬ( B s → D * − $$ {D}_s^{+} $$ D s + ) / ℬ( B 0 → D * − $$ {D}_s^{+} $$ D s + ) is measured to be 0 . 049 ± 0 . 006 ± 0 . 003 ± 0 . 002, where the third uncertainty is due to limited knowledge of the ratio of fragmentation fractions.
Publisher: American Physical Society (APS)
Date: 31-07-2020
Publisher: American Astronomical Society
Date: 03-2022
Abstract: We present a measurement of the high-energy astrophysical muon–neutrino flux with the IceCube Neutrino Observatory. The measurement uses a high-purity selection of 650k neutrino-induced muon tracks from the northern celestial hemisphere, corresponding to 9.5 yr of experimental data. With respect to previous publications, the measurement is improved by the increased size of the event s le and the extended model testing beyond simple power-law hypotheses. An updated treatment of systematic uncertainties and atmospheric background fluxes has been implemented based on recent models. The best-fit single power-law parameterization for the astrophysical energy spectrum results in a normalization of ϕ @ 100 TeV ν μ + ν ¯ μ = 1.44 − 0.26 + 0.25 × 10 − 18 GeV − 1 cm − 2 s − 1 sr − 1 and a spectral index γ SPL = 2.37 − 0.09 + 0.09 , constrained in the energy range from 15 TeV to 5 PeV. The model tests include a single power law with a spectral cutoff at high energies, a log-parabola model, several source-class-specific flux predictions from the literature, and a model-independent spectral unfolding. The data are consistent with a single power-law hypothesis, however, spectra with softening above one PeV are statistically more favorable at a two-sigma level.
Publisher: Springer Science and Business Media LLC
Date: 12-2020
Abstract: The shape of the $$ {B}_s^0\\to {D}_s^{\\ast -}{\\mu}^{+}{\\nu}_{\\mu } $$ B s 0 → D s ∗ − μ + ν μ differential decay rate is obtained as a function of the hadron recoil parameter using proton-proton collision data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb − 1 collected by the LHCb detector. The $$ {B}_s^0\\to {D}_s^{\\ast -}{\\mu}^{+}{\\nu}_{\\mu } $$ B s 0 → D s ∗ − μ + ν μ decay is reconstructed through the decays $$ {D}_s^{\\ast -}\\to {D}_s^{-}\\gamma $$ D s ∗ − → D s − γ and $$ {D}_s^{-}\\to {K}^{-}{K}^{+}{\\pi}^{-} $$ D s − → K − K + π − . The differential decay rate is fitted with the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) parametrisations of the form factors, and the relevant quantities for both are extracted.
Publisher: Springer Science and Business Media LLC
Date: 11-2020
Abstract: A search for the doubly heavy $$ {\\Xi}_{bc}^0 $$ Ξ bc 0 baryon using its decay to the D 0 pK – final state is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb − 1 . No significant signal is found in the invariant mass range from 6.7 to 7.2 GeV/ c 2 . Upper limits are set at 95% credibility level on the ratio of the $$ {\\Xi}_{bc}^0 $$ Ξ bc 0 production cross-section times its branching fraction to D 0 pK − relative to that of the $$ {\\Lambda}_b^0\\to {D}^0{pK}^{-} $$ Λ b 0 → D 0 pK − decay. The limits are set as a function of the $$ {\\Xi}_{bc}^0 $$ Ξ bc 0 mass and lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and in the transverse momentum region from 5 to 25 GeV/ c . Upper limits range from 1 . 7 × 10 − 2 to 3 . 0 × 10 − 1 for the considered $$ {\\Xi}_{bc}^0 $$ Ξ bc 0 mass and lifetime hypotheses.
Publisher: Elsevier BV
Date: 04-2021
Publisher: Springer Science and Business Media LLC
Date: 16-06-2022
DOI: 10.1038/S41467-022-30206-W
Abstract: Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D 0 D 0 π + mass spectrum just below the D *+ D 0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar $${{{{{{\\rm{T}}}}}}}_{{{{{{\\rm{c}}}}}}{{{{{\\rm{c}}}}}}}^{+}$$ T c c + tetraquark with a quark content of $${{{{{\\rm{c}}}}}}{{{{{\\rm{c}}}}}}\\overline{{{{{{\\rm{u}}}}}}}\\overline{{{{{{\\rm{d}}}}}}}$$ c c u ¯ d ¯ and spin-parity quantum numbers J P = 1 + . Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D *+ mesons is consistent with the observed D 0 π + mass distribution. To analyse the mass of the resonance and its coupling to the D * D system, a dedicated model is developed under the assumption of an isoscalar axial-vector $${{{{{{\\rm{T}}}}}}}_{{{{{{\\rm{c}}}}}}{{{{{\\rm{c}}}}}}}^{+}$$ T c c + state decaying to the D * D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the $${{{{{{\\rm{T}}}}}}}_{{{{{{\\rm{c}}}}}}{{{{{\\rm{c}}}}}}}^{+}$$ T c c + state. In addition, an unexpected dependence of the production rate on track multiplicity is observed.
Publisher: IOP Publishing
Date: 04-2021
Abstract: A search for the rare decay is performed using collision data collected with the LHCb dete-ctor at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb −1 . No significant signal of the decay is observed and an upper limit of at 90% confidence level is set on the branching fraction.
Publisher: American Physical Society (APS)
Date: 24-11-2021
Publisher: American Physical Society (APS)
Date: 23-03-2022
Publisher: Springer Science and Business Media LLC
Date: 03-2022
Abstract: The multihadron decays $$ {\\Lambda}_b^0 $$ Λ b 0 → D + pπ−π− and $$ {\\Lambda}_b^0 $$ Λ b 0 → D * + pπ−π− are observed in data corresponding to an integrated luminosity of 3 fb − 1 , collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay $$ {\\Lambda}_b^0 $$ Λ b 0 → $$ {\\Lambda}_c^{+} $$ Λ c + π + π − π − as a normalisation channel, the ratio of branching fractions is measured to be $$ \\frac{\\mathcal{B}\\left({\\Lambda}_b^0\\to {D}^{+}p{\\pi}^{-}{\\pi}^{-}\\right)}{\\mathcal{B}\\left({\\Lambda}_b^0\\to {\\Lambda}_c^0{\\pi}^{+}{\\pi}^{-}{\\pi}^{-}\\right)}\\times \\frac{\\mathcal{B}\\left({D}^{+}\\to {K}^{-}{\\pi}^{+}{\\pi}^{+}\\right)}{\\mathcal{B}\\left({\\Lambda}_c^0\\to {pK}^{-}{\\pi}^{-}\\right)}=\\left(5.35\\pm 0.21\\pm 0.16\\right)\\%, $$ B Λ b 0 → D + p π − π − B Λ b 0 → Λ c 0 π + π − π − × B D + → K − π + π + B Λ c 0 → pK − π − = 5.35 ± 0.21 ± 0.16 % , where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the $$ {\\Lambda}_b^0 $$ Λ b 0 → D *+ pπ − π − and $$ {\\Lambda}_b^0 $$ Λ b 0 → D + pπ − π − decays is found to be $$ \\frac{\\mathcal{B}\\left({\\Lambda}_b^0\\to {D}^{\\ast +}p{\\pi}^{-}{\\pi}^{-}\\right)}{\\mathcal{B}\\left({\\Lambda}_b^0\\to {D}^{+}p{\\pi}^{-}{\\pi}^{-}\\right)}\\times \\left(\\mathcal{B}\\left({D}^{\\ast +}\\to {D}^{+}{\\pi}^0\\right)+\\mathcal{B}\\left({D}^{\\ast +}\\to {D}^{+}\\gamma \\right)\\right)=\\left(61.3\\pm 4.3\\pm 4.0\\right)\\%. $$ B Λ b 0 → D ∗ + p π − π − B Λ b 0 → D + p π − π − × B D ∗ + → D + π 0 + B D ∗ + → D + γ = 61.3 ± 4.3 ± 4.0 % .
Publisher: American Astronomical Society
Date: 03-2023
Abstract: Gamma-ray bursts (GRBs) have long been considered a possible source of high-energy neutrinos. While no correlations have yet been detected between high-energy neutrinos and GRBs, the recent observation of GRB 221009A—the brightest GRB observed by Fermi-GBM to date and the first one to be observed above an energy of 10 TeV—provides a unique opportunity to test for hadronic emission. In this paper, we leverage the wide energy range of the IceCube Neutrino Observatory to search for neutrinos from GRB 221009A. We find no significant deviation from background expectation across event s les ranging from MeV to PeV energies, placing stringent upper limits on the neutrino emission from this source.
Publisher: American Astronomical Society
Date: 05-2022
Abstract: We present the first comprehensive search for high-energy neutrino emission from high- and low-mass X-ray binaries conducted by IceCube. Galactic X-ray binaries are long-standing candidates for the source of Galactic hadronic cosmic rays and neutrinos. The compact object in these systems can be the site of cosmic-ray acceleration, and neutrinos can be produced by interactions of cosmic rays with radiation or gas, in the jet of a microquasar, in the stellar wind, or in the atmosphere of the companion star. We study X-ray binaries using 7.5 yr of IceCube data with three separate analyses. In the first, we search for periodic neutrino emission from 55 binaries in the Northern Sky with known orbital periods. In the second, the X-ray light curves of 102 binaries across the entire sky are used as templates to search for time-dependent neutrino emission. Finally, we search for time-integrated emission of neutrinos for a list of 4 notable binaries identified as microquasars. In the absence of a significant excess, we place upper limits on the neutrino flux for each hypothesis and compare our results with theoretical predictions for several binaries. In addition, we evaluate the sensitivity of the next generation neutrino telescope at the South Pole, IceCube-Gen2, and demonstrate its power to identify potential neutrino emission from these binary sources in the Galaxy.
Publisher: American Physical Society (APS)
Date: 07-09-2021
Publisher: American Physical Society (APS)
Date: 03-03-2022
Publisher: American Physical Society (APS)
Date: 08-09-2020
Publisher: Springer Science and Business Media LLC
Date: 2022
Abstract: The differential cross-section of prompt inclusive production of long-lived charged particles in proton-proton collisions is measured using a data s le recorded by the LHCb experiment at a centre-of-mass energy of $$ \\sqrt{s} $$ s = 13 TeV. The data s le, collected with an unbiased trigger, corresponds to an integrated luminosity of 5 . 4 nb − 1 . The differential cross-section is measured as a function of transverse momentum and pseudorapidity in the ranges p T ∈ [80 , 10 000) MeV /c and η ∈ [2 . 0 , 4 . 8) and is determined separately for positively and negatively charged particles. The results are compared with predictions from various hadronic-interaction models.
Publisher: American Physical Society (APS)
Date: 25-02-2021
Publisher: Springer Science and Business Media LLC
Date: 05-2021
Abstract: The Cabibbo-suppressed decay $$ {\\Lambda}_{\\mathrm{b}}^0 $$ Λ b 0 → χ c1 pπ − is observed for the first time using data from proton-proton collisions corresponding to an integrated luminosity of 6 fb − 1 , collected with the LHCb detector at a centre-of-mass energy of 13 TeV. Evidence for the $$ {\\Lambda}_{\\mathrm{b}}^0 $$ Λ b 0 → χ c2 pπ − decay is also found. Using the $$ {\\Lambda}_{\\mathrm{b}}^0 $$ Λ b 0 → χ c1 pK − decay as normalisation channel, the ratios of branching fractions are measured to be $$ {\\displaystyle \\begin{array}{c}\\frac{\\mathcal{B}\\left({\\Lambda}_{\\mathrm{b}}^0\\to {\\upchi}_{\\mathrm{c}1}{\\mathrm{p}\\uppi}^{-}\\right)}{\\mathcal{B}\\left({\\Lambda}_{\\mathrm{b}}^0\\to {\\upchi}_{\\mathrm{c}1}{\\mathrm{p}\\mathrm{K}}^{-}\\right)}=\\left(6.59\\pm 1.01\\pm 0.22\\right)\\times {10}^{-2},\\\\ {}\\frac{\\mathcal{B}\\left({\\Lambda}_{\\mathrm{b}}^0\\to {\\upchi}_{\\mathrm{c}2}{\\mathrm{p}\\uppi}^{-}\\right)}{\\mathcal{B}\\left({\\Lambda}_{\\mathrm{b}}^0\\to {\\upchi}_{\\mathrm{c}1}{\\mathrm{p}\\uppi}^{-}\\right)}=0.95\\pm 0.30\\pm 0.04\\pm 0.04,\\\\ {}\\frac{\\mathcal{B}\\left({\\Lambda}_{\\mathrm{b}}^0\\to {\\upchi}_{\\mathrm{c}2}{\\mathrm{p}\\mathrm{K}}^{-}\\right)}{\\mathcal{B}\\left({\\Lambda}_{\\mathrm{b}}^0\\to {\\upchi}_{\\mathrm{c}1}{\\mathrm{p}\\mathrm{K}}^{-}\\right)}=1.06\\pm 0.05\\pm 0.04\\pm 0.04,\\end{array}} $$ B Λ b 0 → χ c 1 pπ − B Λ b 0 → χ c 1 pK − = 6.59 ± 1.01 ± 0.22 × 10 − 2 , B Λ b 0 → χ c 2 pπ − B Λ b 0 → χ c 1 pπ − = 0.95 ± 0.30 ± 0.04 ± 0.04 , B Λ b 0 → χ c 2 pK − B Λ b 0 → χ c 1 pK − = 1.06 ± 0.05 ± 0.04 ± 0.04 , where the first uncertainty is statistical, the second is systematic and the third is due to the uncertainties in the branching fractions of χ c1 , 2 → J / ψγ decays.
Publisher: American Astronomical Society
Date: 03-2023
Abstract: Galactic PeV cosmic-ray accelerators (PeVatrons) are Galactic sources theorized to accelerate cosmic rays up to PeV in energy. The accelerated cosmic rays are expected to interact hadronically with nearby ambient gas or the interstellar medium, resulting in γ -rays and neutrinos. Recently, the Large High Altitude Air Shower Observatory (LHAASO) identified 12 γ -ray sources with emissions above 100 TeV, making them candidates for PeVatrons. While at these high energies the Klein–Nishina effect exponentially suppresses leptonic emission from Galactic sources, evidence for neutrino emission would unequivocally confirm hadronic acceleration. Here, we present the results of a search for neutrinos from these γ -ray sources and stacking searches testing for excess neutrino emission from all 12 sources as well as their subcatalogs of supernova remnants and pulsar wind nebulae with 11 yr of track events from the IceCube Neutrino Observatory. No significant emissions were found. Based on the resulting limits, we place constraints on the fraction of γ -ray flux originating from the hadronic processes in the Crab Nebula and LHAASO J2226+6057.
Publisher: Springer Science and Business Media LLC
Date: 10-2020
Abstract: Searches are performed for a low-mass dimuon resonance, X , produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using a data s le corresponding to an integrated luminosity of 5.1 fb − 1 and collected with the LHCb detector. The X bosons can either decay promptly or displaced from the proton-proton collision, where in both cases the requirements placed on the event and the assumptions made about the production mechanisms are kept as minimal as possible. The searches for promptly decaying X bosons explore the mass range from near the dimuon threshold up to 60 GeV, with nonnegligible X widths considered above 20 GeV. The searches for displaced X → μ + μ − decays consider masses up to 3 GeV. None of the searches finds evidence for a signal and 90% confidence-level exclusion limits are placed on the X → μ + μ − cross sections, each with minimal model dependence. In addition, these results are used to place world-leading constraints on GeV-scale bosons in the two-Higgs-doublet and hidden-valley scenarios.
Publisher: American Physical Society (APS)
Date: 04-06-2020
Publisher: Springer Science and Business Media LLC
Date: 04-2022
DOI: 10.1140/EPJC/S10052-022-10186-3
Abstract: A search is performed for massive long-lived particles (LLPs) decaying semileptonically into a muon and two quarks. Two kinds of LLP production processes were considered. In the first, a Higgs-like boson with mass from 30 to 200 $$\\text {\\,GeV\\!/}c^2$$ \\,GeV\\!/ c 2 is produced by gluon fusion and decays into two LLPs. The analysis covers LLP mass values from 10 $$\\text {\\,GeV\\!/}c^2$$ \\,GeV\\!/ c 2 up to about one half the Higgs-like boson mass. The second LLP production mode is directly from quark interactions, with LLP masses from 10 to 90 $$\\text {\\,GeV\\!/}c^2$$ \\,GeV\\!/ c 2 . The LLP lifetimes considered range from 5 to 200 ps. This study uses LHCb data collected from proton-proton collisions at $$\\sqrt{s} = 13\\text {\\,TeV} $$ s = 13 \\,TeV , corresponding to an integrated luminosity of 5.4 $$\\text {\\,fb} ^{-1}$$ \\,fb - 1 . No evidence of these long-lived states has been observed, and upper limits on the production cross-section times branching ratio have been set for each model considered.
Publisher: Springer Science and Business Media LLC
Date: 14-06-2023
Abstract: A search for the lepton-flavour violating decays B 0 → K *0 μ ± e ∓ and $$ {B}_s^0 $$ B s 0 → ϕμ ± e ∓ is presented, using proton-proton collision data collected by the LHCb detector at the LHC, corresponding to an integrated luminosity of 9 fb − 1 . No significant signals are observed and upper limits of $$ {\\displaystyle \\begin{array}{c}\\mathcal{B}\\left({B}^0\\to {K}^{\\ast 0}{\\mu}^{+}{e}^{-}\\right) .7\\times {10}^{-9}\\left(6.9\\times {10}^{-9}\\right),\\\\ {}\\mathcal{B}\\left({B}^0\\to {K}^{\\ast 0}{\\mu}^{-}{e}^{+}\\right) .8\\times {10}^{-9}\\left(7.9\\times {10}^{-9}\\right),\\\\ {}\\mathcal{B}\\left({B}^0\\to {K}^{\\ast 0}{\\mu}^{\\pm }{e}^{\\mp}\\right) .1\\times {10}^{-9}\\left(11.7\\times {10}^{-9}\\right),\\\\ {}\\mathcal{B}\\left({B}_s^0\\to \\phi {\\mu}^{\\pm }{e}^{\\mp}\\right) .0\\times {10}^{-9}\\left(19.8\\times {10}^{-9}\\right)\\end{array}} $$ B B 0 → K ∗ 0 μ + e − 5.7 × 10 − 9 6.9 × 10 − 9 , B B 0 → K ∗ 0 μ − e + 6.8 × 10 − 9 7.9 × 10 − 9 , B B 0 → K ∗ 0 μ ± e ∓ 10.1 × 10 − 9 11.7 × 10 − 9 , B B s 0 → ϕ μ ± e ∓ 16.0 × 10 − 9 19.8 × 10 − 9 are set at 90% (95%) confidence level. These results constitute the world’s most stringent limits to date, with the limit on the decay $$ {B}_s^0 $$ B s 0 → ϕμ ± e ∓ the first being set. In addition, limits are reported for scalar and left-handed lepton-flavour violating New Physics scenarios.
Publisher: Springer Science and Business Media LLC
Date: 04-2021
Abstract: Measurements of CP observables in B ± → D (*) K ± and B ± → D (*) π ± decays are presented, where D (∗) indicates a neutral D or D ∗ meson that is an admixture of meson and anti-meson states. Decays of the D (∗) meson to the Dπ 0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon. Decays of the D meson are reconstructed in the K ± π ∓ , K + K − , and π + π − final states. The analysis uses a s le of charged B mesons produced in proton-proton collisions and collected with the LHCb experiment, corresponding to integrated luminosities of 2.0, 1.0, and 5.7 fb − 1 taken at centre-of-mass energies of 7, 8, and 13 TeV, respectively. The measurements of partially reconstructed B ± → D (*) K ± and B ± → D (∗) π ± with D → K ∓ π ± decays are the first of their kind, and a first observation of the B ± → $$ {\\left(D{\\pi}^0\\right)}_{D^{\\ast }}{\\pi}^{\\pm } $$ D π 0 D ∗ π ± decay is made with a significance of 6.1 standard deviations. All CP observables are measured with world-best precision, and in combination with other LHCb results will provide strong constraints on the CKM angle γ .
Publisher: Springer Science and Business Media LLC
Date: 03-2022
Abstract: Searches for rare $$ {B}_s^0 $$ B s 0 and B 0 decays into four muons are performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb − 1 . Direct decays and decays via light scalar and J/ψ resonances are considered. No evidence for the six decays searched for is found and upper limits at the 95% confidence level on their branching fractions ranging between 1 . 8 × 10 − 10 and 2 . 6 × 10 − 9 are set.
Publisher: arXiv
Date: 2022
Publisher: American Physical Society (APS)
Date: 06-01-2021
Publisher: IOP Publishing
Date: 09-2021
Abstract: The first search for the doubly heavy baryon and a search for the baryon are performed using collision data collected via the experiment from 2016 to 2018 at a centre-of-mass energy of , corresponding to an integrated luminosity of 5.2 . The baryons are reconstructed via their decays to and . No significant excess is found for invariant masses between 6700 and 7300 , in a rapidity range from 2.0 to 4.5 and a transverse momentum range from 2 to 20 . Upper limits are set on the ratio of the and production cross-section times the branching fraction to ( ) relative to that of the ( ) baryon, for different lifetime hypotheses, at 95% confidence level. The upper limits range from to for the ( ) decay, and from to for the ( ) decay, depending on the considered mass and lifetime of the ( ) baryon.
Publisher: Springer Science and Business Media LLC
Date: 2020
DOI: 10.1140/EPJC/S10052-019-7486-9
Abstract: This erratum corrects measurements of the prompt and secondary (from- b ).
Publisher: American Physical Society (APS)
Date: 24-08-2022
Publisher: arXiv
Date: 2022
Publisher: Springer Science and Business Media LLC
Date: 12-2021
Abstract: A search for the doubly charmed baryon $$ {\\varXi}_{cc}^{+} $$ Ξ cc + is performed in the $$ {\\varXi}_c^{+}{\\pi}^{-}{\\pi}^{+} $$ Ξ c + π − π + invariant-mass spectrum, where the $$ {\\varXi}_c^{+} $$ Ξ c + baryon is reconstructed in the pK − π + final state. The study uses proton-proton collision data collected with the LHCb detector at a centre- of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fb − 1 . No significant signal is observed in the invariant-mass range of 3.4–3.8 GeV/ c 2 . Upper limits are set on the ratio of branching fractions multiplied by the production cross-section with respect to the $$ {\\varXi}_{cc}^{++} $$ Ξ cc + + → ( $$ {\\varXi}_c^{+} $$ Ξ c + → pK − π + ) π + decay for different $$ {\\varXi}_{cc}^{+} $$ Ξ cc + mass and lifetime hypotheses in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2.5 to 25 GeV/ c . The results from this search are combined with a previously published search for the $$ {\\varXi}_{cc}^{+} $$ Ξ cc + → $$ {\\varLambda}_c^{+} $$ Λ c + K − π + decay mode, yielding a maximum local significance of 4.0 standard deviations around the mass of 3620 MeV/ c 2 , including systematic uncertainties. Taking into account the look-elsewhere effect in the 3.5–3.7 GeV/ c 2 mass window, the combined global significance is 2.9 standard deviations including systematic uncertainties.
Publisher: Springer Science and Business Media LLC
Date: 31-08-2021
DOI: 10.1007/S11433-021-1742-7
Abstract: A search for the doubly charmed baryon Ω cc + with the decay mode Ω cc + → Ξ c + K − π + is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb −1 . No significant signal is observed within the invariant mass range of 3.6 to 4.0GeV/ c 2 . Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the Ω cc + → Ξ c + K − π + decay with respect to the $$\\Xi _{cc}^{ + + } \\to \\Lambda _c^ + {K^ - }{\\pi ^ + }{\\pi ^ + }$$ Ξ c c + + → Λ c + K − π + π + decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for different hypotheses on the Ω cc + mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/ c .
Publisher: American Physical Society (APS)
Date: 07-12-2020
Publisher: American Physical Society (APS)
Date: 03-06-2022
Publisher: American Physical Society (APS)
Date: 26-10-2021
Publisher: Springer Science and Business Media LLC
Date: 03-2021
Abstract: The CKM angle γ is measured for the first time from mixing-induced CP violation between $$ {B}_s^0\\to {D}_s^{\\mp }{K}^{\\pm }{\\pi}^{\\pm }{\\pi}^{\\mp } $$ B s 0 → D s ∓ K ± π ± π ∓ and $$ {\\overline{B}}_s^0\\to {D}_s^{\\pm }{K}^{\\mp }{\\pi}^{\\mp }{\\pi}^{\\pm } $$ B ¯ s 0 → D s ± K ∓ π ∓ π ± decays reconstructed in proton-proton collision data corresponding to an integrated luminosity of 9 fb − 1 recorded with the LHCb detector. A time-dependent litude analysis is performed to extract the CP -violating weak phase γ − 2 β s and, subsequently, γ by taking the $$ {B}_s^0\\hbox{-} {\\overline{B}}_s^0 $$ B s 0 ‐ B ¯ s 0 mixing phase β s as an external input. The measurement yields γ = (44 ± 12)° modulo 180°, where statistical and systematic uncertainties are combined. An alternative model-independent measurement, integrating over the five-dimensional phase space of the decay, yields $$ \\gamma =\\left({44}_{-13}^{+20}\\right){}^{\\circ} $$ γ = 44 − 13 + 20 ° modulo 180°. Moreover, the $$ {B}_s^0\\hbox{-} {\\overline{B}}_s^0 $$ B s 0 ‐ B ¯ s 0 oscillation frequency is measured from the flavour-specific control channel $$ {B}_s^0\\to {D}_s^{-}{\\pi}^{+}{\\pi}^{+}{\\pi}^{-} $$ B s 0 → D s − π + π + π − to be ∆ m s = (17 . 757 ± 0 . 007(stat) ± 0 . 008(syst)) ps − 1 , consistent with and more precise than the current world-average value.
Publisher: Springer Science and Business Media LLC
Date: 12-2021
Abstract: A data set corresponding to an integrated luminosity of 9 fb − 1 of proton-proton collisions collected by the LHCb experiment has been analysed to search for $$ {B}_c^{+}\\to {D}_{(s)}^{\\left(\\ast \\right)+}{\\genfrac{}{}{0pt}{}{\\left(\\hbox{---} \\right)}{D}}^{\\left(\\ast \\right)0} $$ B c + → D s ∗ + — D ∗ 0 decays. The decays are fully or partially reconstructed, where one or two missing neutral pions or photons from the decay of an excited charm meson are allowed. Upper limits for the branching fractions, normalised to B + decays to final states with similar topologies, are obtained for sixteen $$ {B}_c^{+} $$ B c + decay modes. For the decay $$ {B}_c^{+}\\to {D}_s^{+}{\\overline{D}}^0 $$ B c + → D s + D ¯ 0 , an excess with a significance of 3.4 standard deviations is found.
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: Springer Science and Business Media LLC
Date: 07-2022
Abstract: Coherent production of J/ψ mesons is studied in ultraperipheral lead-lead collisions at a nucleon-nucleon centre-of-mass energy of 5 TeV, using a data s le collected by the LHCb experiment corresponding to an integrated luminosity of about 10 μb −1 . The J/ψ mesons are reconstructed in the dimuon final state and are required to have transverse momentum below 1 GeV. The cross-section within the rapidity range of 2 . 0 y 4 . 5 is measured to be 4 . 45 ± 0 . 24 ± 0 . 18 ± 0 . 58 mb, where the first uncertainty is statistical, the second systematic and the third originates from the luminosity determination. The cross-section is also measured in J/ψ rapidity intervals. The results are compared to predictions from phenomenological models.
Publisher: Springer Science and Business Media LLC
Date: 03-2021
Abstract: A search for the $$ {B}_{\\mathrm{s}}^0 $$ B s 0 → D *± D ∓ decay is performed using proton-proton collision data at centre-of-mass energies of 7, 8 and 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb − 1 . The decay is observed with a high significance and its branching fraction relative to the B 0 → D *± D ∓ decay is measured to be $$ \\frac{\\mathrm{\\mathcal{B}}\\left({B}_s^0\\to {D}^{\\ast \\pm }{D}^{\\mp}\\right)}{\\left({B}^0\\to {D}^{\\ast \\pm }{D}^{\\mp}\\right)}=0.137\\pm 0.017\\pm 0.002\\pm 0.006, $$ ℬ B s 0 → D ∗ ± D ∓ B 0 → D ∗ ± D ∓ = 0.137 ± 0.017 ± 0.002 ± 0.006 , where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the $$ {B}_{\\mathrm{s}}^0 $$ B s 0 and B 0 hadronisation fractions.
Publisher: Springer Science and Business Media LLC
Date: 11-05-2022
Abstract: A search for the decay B 0 → ϕμ + μ − is performed using proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV collected by the LHCb experiment and corresponding to an integrated luminosity of 9 fb − 1 . No evidence for the B 0 → ϕμ + μ − decay is found and an upper limit on the branching fraction, excluding the ϕ and charmonium regions in the dimuon spectrum, of 4 . 4 × 10 − 3 at a 90% credibility level, relative to that of the $$ {B}_s^0 $$ B s 0 → ϕμ + μ − decay, is established. Using the measured $$ {B}_s^0 $$ B s 0 → ϕμ + μ − branching fraction and assuming a phase-space model, the absolute branching fraction of the decay B 0 → ϕμ + μ − in the full q 2 range is determined to be less than 3 . 2 × 10 − 9 at a 90% credibility level.
Publisher: American Astronomical Society
Date: 10-2022
Abstract: Galaxy clusters have the potential to accelerate cosmic rays (CRs) to ultrahigh energies via accretion shocks or embedded CR acceleration sites. The CRs with energies below the Hillas condition will be confined within the cluster and eventually interact with the intracluster medium gas to produce secondary neutrinos and gamma rays. Using 9.5 yr of muon neutrino track events from the IceCube Neutrino Observatory, we report the results of a stacking analysis of 1094 galaxy clusters with masses ≳10 14 M ⊙ and redshifts between 0.01 and ∼1 detected by the Planck mission via the Sunyaev–Zel’dovich effect. We find no evidence for significant neutrino emission and report upper limits on the cumulative unresolved neutrino flux from massive galaxy clusters after accounting for the completeness of the catalog up to a redshift of 2, assuming three different weighting scenarios for the stacking and three different power-law spectra. Weighting the sources according to mass and distance, we set upper limits at a 90% confidence level that constrain the flux of neutrinos from massive galaxy clusters (≳10 14 M ⊙ ) to be no more than 4.6% of the diffuse IceCube observations at 100 TeV, assuming an unbroken E −2.5 power-law spectrum.
Publisher: Springer Science and Business Media LLC
Date: 02-2021
Abstract: 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 $$ {K}_{\\mathrm{S}}^0 $$ K S 0 π + π − and $$ {K}_{\\mathrm{S}}^0 $$ K S 0 K + K − (commonly denoted $$ {K}_{\\mathrm{S}}^0 $$ K 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 litude. The observables are inter- preted in terms of the CKM angle γ . Using a data s le 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 $$ \\left({68.7}_{-5.1}^{+5.2}\\right){}^{\\circ} $$ 68.7 − 5.1 + 5.2 ° . The hadronic parameters $$ {r}_B^{D K},{r}_B^{D\\pi},{\\delta}_B^{D K},\\kern0.5em \\mathrm{and}\\kern0.5em {\\delta}_B^{D\\pi} $$ r B DK , r B Dπ , δ B DK , and δ B Dπ , which are the ratios and strong-phase differences of the suppressed and favoured B ± decays, are also reported.
Publisher: Springer Science and Business Media LLC
Date: 10-2021
Abstract: This article presents differential measurements of the asymmetry between $$ {\\varLambda}_b^0 $$ Λ b 0 and $$ {\\overline{\\varLambda}}_b^0 $$ Λ ¯ b 0 baryon production rates in proton-proton collisions at centre-of-mass energies of $$ \\sqrt{s} $$ s = 7 and 8 TeV collected with the LHCb experiment, corresponding to an integrated luminosity of 3 fb − 1 . The $$ {\\varLambda}_b^0 $$ Λ b 0 baryons are reconstructed through the inclusive semileptonic decay $$ {\\varLambda}_b^0 $$ Λ b 0 → $$ {\\varLambda}_c^{+} $$ Λ c + μ − $$ \\overline{\\nu} $$ ν ¯ μ X . The production asymmetry is measured both in intervals of rapidity in the range 2 . 15 y 4 . 10 and transverse momentum in 2 p T 27 GeV/ c . The results are found to be incompatible with symmetric production with a significance of 5.8 standard deviations for both $$ \\sqrt{s} $$ s = 7 and 8 TeV data, assuming no CP violation in the decay. There is evidence for a trend as a function of rapidity with a significance of 4 standard deviations. Comparisons to predictions from hadronisation models in P ythia and heavy-quark recombination are provided. This result constitutes the first observation of a particle-antiparticle asymmetry in b -hadron production at LHC energies.
Publisher: American Physical Society (APS)
Date: 07-04-2022
Publisher: American Physical Society (APS)
Date: 05-03-2021
Publisher: arXiv
Date: 2022
Publisher: American Physical Society (APS)
Date: 20-09-2021
Publisher: American Physical Society (APS)
Date: 27-12-2021
Publisher: arXiv
Date: 2021
Publisher: Elsevier BV
Date: 07-2021
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for James Mead.