| 1031. |
- Aaij, R., et al.
(author)
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Measurement of J/psi production cross-sections in pp collisions at root s=5 TeV
- 2021
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In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :11
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Journal article (peer-reviewed)abstract
- The production cross-sections of J/psi mesons in proton-proton collisions at a centre-of-mass energy of root s = 5TeV are measured using a data sample 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/psi mesons produced promptly and from beauty hadron decays (nonprompt). With the assumption of unpolarised J/psi mesons, the production cross-sections integrated over the kinematic range 0 < p(T) < 20 GeV/c and 2.0 < y < 4.5 are sigma(prompt) J/psi = 8.154 +/- 0.010 +/- 0.283 mu b, sigma(nonprompt) J/psi = 0.820 +/- 0.003 +/- 0.034 mu b, where the first uncertainties are statistical and the second systematic. These cross-sections are compared with those at root s = 8TeV and 13TeV, and are used to update the measurement of the nuclear modification factor in proton-lead collisions for J/psi mesons at a centre-of-mass energy per nucleon pair of root s(NN) = 5TeV. The results are compared with theoretical predictions.
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| 1032. |
- Aaij, R., et al.
(author)
-
Measurement of J/ψ-pair production in pp collisions at √‾s = 13 TeV and study of gluon transverse-momentum dependent PDFs
- 2024
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In: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :3
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Journal article (peer-reviewed)abstract
- The production cross-section of J/ψ pairs in proton-proton collisions at a centre-of-mass energy of s√ = 13 TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb−1 collected by the LHCb experiment. The measurement is performed with both J/ψ mesons in the transverse momentum range 0 < pT < 14 GeV/c and rapidity range 2.0 < y < 4.5. The cross-section of this process is measured to be 16.36 ± 0.28 (stat) ± 0.88 (syst) nb. The contributions from single-parton scattering and double-parton scattering are separated based on the dependence of the cross-section on the absolute rapidity difference ∆y between the two J/ψ mesons. The effective cross-section of double-parton scattering is measured to be σeff = 13.1 ± 1.8 (stat) ± 2.3 (syst) mb. The distribution of the azimuthal angle ϕCS of one of the J/ψ mesons in the Collins-Soper frame and the pT-spectrum of the J/ψ pairs are also measured for the study of the gluon transverse-momentum dependent distributions inside protons. The extracted values of ⟨cos 2ϕCS⟩ and ⟨cos 4ϕCS⟩ are consistent with zero, but the presence of azimuthal asymmetry at a few percent level is allowed.
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| 1033. |
- Aaij, R., et al.
(author)
-
Measurement of lepton universality parameters in B plus ? : K plus l + l - and B0? K?0l+l- decays
- 2023
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In: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:3
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Journal article (peer-reviewed)abstract
- A simultaneous analysis of the B thorn & RARR; K thorn e thorn e- and B0 & RARR; K & DBLBOND;0e thorn e- decays is performed to test muonelectron universality in two ranges of the square of the dilepton invariant mass, q2. The measurement uses a sample of beauty meson decays produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb-1. A sequence of multivariate selections and strict particle identification requirements produce a higher signal purity and a better statistical sensitivity per unit luminosity than previous LHCb lepton universality tests using the same decay modes. Residual backgrounds due to misidentified hadronic decays are studied using data and included in the fit model. Each of the four lepton universality measurements reported is either the first in the given q2 interval or supersedes previous LHCb measurements. The results are compatible with the predictions of the Standard Model.
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| 1034. |
- Aaij, R., et al.
(author)
-
Measurement of prompt D+ and Ds+ production in pPb collisions at √ˆšsNN=5.02 TeV
- 2024
-
In: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479.
-
Journal article (peer-reviewed)abstract
- The production of prompt D+ and D+s mesons is studied in proton-lead collisions at a centre-of-mass energy of √sNN = 5.02TeV. The data sample corresponding to an integrated luminosity of (1.58 ± 0.02)nb-1 is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using D+ and D+s candidates with transverse momentum in the range of 0 < pT < 14 GeV/c and rapidities in the ranges of 1.5 < y* < 4.0 and -5.0 < y* < -2.5 in the nucleon-nucleon centre-of-mass system. For both particles, the nuclear modification factor and the forward-backward production ratio are determined. These results are compared with theoretical models that include initial-state nuclear effects. In addition, measurements of the cross-section ratios between D+, D+s and D0 mesons are presented, providing a baseline for studying the charm hadronization in lead-lead collisions at LHC energies.
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| 1035. |
- Aaij, R., et al.
(author)
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Measurement of the B0s→μ+μ− decay properties and search for the B0→μ+μ− and B0s→μ+μ−γ decays
- 2022
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In: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 105:1
-
Journal article (peer-reviewed)abstract
- An improved measurement of the decay B-s(0) -> mu(+)mu(-) and searches for the decays B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-)gamma are performed at the LHCb experiment using data collected in proton-proton collisions at root s = 7, 8 and 13 TeV, corresponding to integrated luminosities of 1, 2 and 6 fb(-1), respectively. The B-s(0) -> mu(+)mu(-) branching fraction and effective lifetime are measured to be B(B-s(0) -> mu(+)mu(-)) = (3.09(-0.43-0.11)(+0.46+0.15)) x 10(-9) and tau(B-s(0) -> mu(+)mu(-)) = (2.07 +/- 0.29 +/- 0.03) ps, respectively, where the uncertain-ties include both statistical and systematic contributions. No significant signal for B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-) gamma decays is found and the upper limits B(B-0 -> mu(+)mu(-)) < 2.6 x 10(-10) and B(B-s(0) -> mu(+)mu(-)gamma) 2.0 x 10(-9) at 95% confidence level are determined, where the latter is limited to the range m(mu mu) > 4.9 GeV/c(2). Additionally, the ratio between the B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-) branching fractions is measured to be R mu+mu- < 0.095 at 95% confidence level. The results are in agreement with the Standard Model predictions.
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| 1036. |
- Aaij, R., et al.
(author)
-
Measurement of the branching fraction of the B0-> Ds+pi- decay
- 2021
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In: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 81:4
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Journal article (peer-reviewed)abstract
- A branching fraction measurement of the B0 -> Ds+pi- decay is presented using proton-proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of 5.0fb-1. The branching fraction is found to be B(B0 -> Ds+pi-)=(19.4 +/- 1.8 +/- 1.3 +/- 1.2)x10-6, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the B0 -> D-pi+, Ds+-> K+K-pi+ and D--> K+pi-pi- branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a b -> u charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element Vub. Additionally, the collision energy dependence of the hadronisation-fraction ratio fs/fd is measured through Bs0 -> Ds+pi- and B0 -> D-pi + decays.
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| 1037. |
- Aaij, R., et al.
(author)
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Measurement of the Branching Fractions B(B0→p¯pp¯p) and B(B0s→p¯pp¯p)
- 2023
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In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 131:9
-
Journal article (peer-reviewed)abstract
- Searches for the rare hadronic decays B0→p¯pp¯p and B0s→p¯pp¯p are performed using proton-proton collision data recorded by the LHCb experiment and corresponding to an integrated luminosity of 9 fb−1. Significances of 9.3σ and 4.0σ, including statistical and systematic uncertainties, are obtained for the B0→p¯pp¯p and B0s→p¯pp¯p signals, respectively. The branching fractions are measured relative to the topologically similar normalization decays B0→J/ψ(→p¯p)K*0(→K+π−) and B0s→J/ψ(→p¯p)ϕ(→K+K−). The branching fractions are measured to be B(B0→p¯pp¯p)=(2.2±0.4±0.1±0.1)×10−8 and B(B0s→p¯pp¯p)=(2.3±1.0±0.2±0.1)×10−8. In these measurements, the first uncertainty is statistical, the second is systematic, and the third one is due to the external branching fraction of the normalization channel.
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| 1038. |
- Aaij, R., et al.
(author)
-
Measurement of the charm mixing parameter y(CP)-y(CP)(K pi) using two-body D-0 meson decays
- 2022
-
In: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 105:9
-
Journal article (peer-reviewed)abstract
- A measurement of the ratios of the effective decay widths of D-0 -> pi(-)pi(+) and D-0 -> K- K+ decays over that of D-0 -> K-pi(+) decays is performed with the LHCb experiment using proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb(-1). These observables give access to the charm mixing parameters y(CP)(pi pi) - y(CP)(K pi )and y(CP)(KK) -y(CP)(K pi), and are measured as y(CP)(pi pi) - y(CP)(K pi) = (6.57 +/- 0.53 +/- 0.16) x 10(-3), y(CP)(KK) - y(CP)(K pi) = (7.08 +/- 0.30 +/- 0.14) x 10(-3), where the first uncertainties are statistical and the second systematic. The combination of the two measurements is Y-CP - y(CP)(K pi) = (6.96 +/- 0.26 +/- 0.13) x 10(-3), which is four times more precise than the previous world average.
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| 1039. |
- Aaij, R., et al.
(author)
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Measurement of the CKM angle γ with B± → D[K∓π±π±π∓] h± decays using a binned phase-space approach
- 2023
-
In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :7
-
Journal article (peer-reviewed)abstract
- The CKM angle gamma is determined from CP-violating observables measured in B-+/- -> D[K--/+pi(+/-)pi(+/-)pi(-/+)]h(+/-), (h = K, pi) decays, where the measurements are performed in bins of the decay phase-space of the D meson. Using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13TeV, corresponding to a total integrated luminosity of 9 fb(-1), gamma is determined to be gamma = (54.8 (+6.0)(-5.8) (+0.6)(-0.6) (+6.7)(-4.3))degrees, where the first uncertainty is statistical, the second systematic and the third from the external inputs on the coherence factors and strong phases of the D-meson decays.
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| 1040. |
- Aaij, R., et al.
(author)
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Measurement of the CKM angle γ using the B±→†’ D*h± channels
- 2023
-
In: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :12
-
Journal article (peer-reviewed)abstract
- A measurement of the CP-violating observables from B -> (DK +/-)-K-* and B-+/- -> D-*pi(+/-) decays is presented, where D-*(D) is an admixture of D-*0 and D-0 (D-0 and (0)) states and is reconstructed through the decay chains D-*-> D pi(0)/gamma and D -> KS0 pi+pi-/KS0K+K-. The measurement is performed by analysing the signal yield variation across the D decay phase space and is independent of any amplitude model. The data sample used was collected by the LHCb experiment in proton-proton collisions and corresponds to a total integrated luminosity of 9 fb(-1) at centre-of-mass energies of 7, 8 and 13 TeV. The CKM angle gamma is determined to be (69(-14)(+13))degrees using the measured CP-violating observables. The hadronic parameters r(B)(D)*(K +/-),r(B)(D)*(pi +/-),delta(D)(B)*(K +/-),delta(D)(B)*(pi +/-), which are the ratios and strong phase differences between favoured and suppressed B-+/- decays, are also reported.
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