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  1. A bstract 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 sample 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 firstmore »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.« less
    Free, publicly-accessible full text available July 1, 2023
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  4. A bstract 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 − γmore ») < 1 . 3 × 10 − 4 at 95% confidence level is obtained.« less
    Free, publicly-accessible full text available January 1, 2023
  5. Free, publicly-accessible full text available January 1, 2023
  6. A bstract The differential cross-section of prompt inclusive production of long-lived charged particles in proton-proton collisions is measured using a data sample recorded by the LHCb experiment at a centre-of-mass energy of $$ \sqrt{s} $$ s = 13 TeV. The data sample, 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 formore »positively and negatively charged particles. The results are compared with predictions from various hadronic-interaction models.« less
    Free, publicly-accessible full text available January 1, 2023
  7. 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 firstmore »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.« less
    Free, publicly-accessible full text available January 1, 2023
  8. Abstract A flavour-tagged time-dependent angular analysis of $${{B} ^0_{s}} \!\rightarrow {{J /\psi }} \phi $$ B s 0 → J / ψ ϕ decays is presented where the $${J /\psi }$$ J / ψ meson is reconstructed through its decay to an $$e ^+e ^-$$ e + e - pair. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and $$8\text {\,Te V} $$ 8 \,Te V , corresponding to an integrated luminosity of $$3 \text {\,fb} ^{-1} $$ 3 \,fb - 1 . The $$C\!P$$ C P -violating phasemore »and lifetime parameters of the $${B} ^0_{s} $$ B s 0 system are measured to be $${\phi _{{s}}} =0.00\pm 0.28\pm 0.07\text {\,rad}$$ ϕ s = 0.00 ± 0.28 ± 0.07 \,rad , $${\Delta \Gamma _{{s}}} =0.115\pm 0.045\pm 0.011\text {\,ps} ^{-1} $$ Δ Γ s = 0.115 ± 0.045 ± 0.011 \,ps - 1 and $${\Gamma _{{s}}} =0.608\pm 0.018\pm 0.012\text {\,ps} ^{-1} $$ Γ s = 0.608 ± 0.018 ± 0.012 \,ps - 1 where the first uncertainty is statistical and the second systematic. This is the first time that $$C\!P$$ C P -violating parameters are measured in the $${{B} ^0_{s}} \!\rightarrow {{J /\psi }} \phi $$ B s 0 → J / ψ ϕ decay with an $$e ^+e ^-$$ e + e - pair in the final state. The results are consistent with previous measurements in other channels and with the Standard Model predictions.« less
    Free, publicly-accessible full text available November 1, 2022
  9. Free, publicly-accessible full text available November 1, 2022