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A bstract The isospin asymmetries of B → Kμ + μ − and B → K * μ + μ − decays and the partial branching fractions of the B 0 → K 0 μ + μ − , B + → K + μ + μ − and B + → K *+ μ + μ − decays are measured as functions of the dimuon mass squared, q 2 . The data used correspond to an integrated luminosity of 3 fb −1 from proton-proton collisions collected with the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV in 2011 and 2012, respectively. The isospin asymmetries are both consistent with the Standard Model expectations. The three measured branching fractions favour lower values than their respective theoretical predictions, however they are all individually consistent with the Standard Model.

Mesons comprising a beauty quark and strange quark can oscillate between particle ( B s 0 ) and antiparticle ( 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 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. The LHCb collaboration reports an improved measurement of the oscillation frequency of mesons consisting of a bottom quark and strange quark, which is then combined with previous results.

The Ξ b 0 → Ξ c + D s - and Ξ b - → Ξ c 0 D s - decays are observed for the first time using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of s = 13 TeV , corresponding to an integrated luminosity of 5.1 fb - 1 . The branching fractions times the production cross-sections of Ξ b baryons relative to that of Λ b 0 baryon are measured to be R Ξ b 0 Λ b 0 ≡ σ Ξ b 0 σ Λ b 0 × B Ξ b 0 → Ξ c + D s - B Λ b 0 → Λ c 0 D s - = ( 15.8 ± 1.1 ± 0.6 ± 7.7 ) % , R Ξ b - Λ b 0 ≡ σ Ξ b - σ Λ b 0 × B Ξ b - → Ξ c 0 D s - B Λ b 0 → Λ c 0 D s - = ( 16.9 ± 1.3 ± 0.9 ± 4.3 ) % , where the first uncertainties are statistical, the second systematic, and the third due to the uncertainties on the decay branching fractions of relevant charmed baryons. The masses of Ξ b 0 and Ξ b - baryons are measured to be m Ξ b 0 = 5791.12 ± 0.60 ± 0.45 ± 0.24 MeV / c 2 and m Ξ b - = 5797.02 ± 0.63 ± 0.49 ± 0.29 MeV / c 2 , where the uncertainties are statistical, systematic, and those due to charmed-hadron masses, respectively.

The first observation of the Ξ b 0 → J / ψ Ξ - π + decay and the most precise measurement of the branching fraction of the Λ b 0 → J / ψ Ξ - K + decay are reported, using proton-proton collision data from the LHCb experiment collected in 2016–2018 at a centre-of-mass energy of 13 \\,Te V , corresponding to an integrated luminosity of 5.4 \\,fb - 1 . Using the Λ b 0 → J / ψ Λ and Ξ b - → J / ψ Ξ - decays as normalisation channels, the ratios of branching fractions are measured to be B ( Λ b 0 → J / ψ Ξ - K + ) B ( Λ b 0 → J / ψ Λ ) = ( 1.17 ± 0.14 ± 0.08 ) × 10 - 2 , B ( Ξ b 0 → J / ψ Ξ - π + ) B ( Ξ b - → J / ψ Ξ - ) = ( 11.9 ± 1.4 ± 0.6 ) × 10 - 2 , where the first uncertainty is statistical and the second systematic.

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Abstract The production cross-sections of B mesons are measured in pp collisions at a centre-of-mass energy of 7 TeV, using data collected with the LHCb detector corresponding to a integrated luminosity of 0.36 fb^sup -1^. The B ^sup +^, B ^sup 0^ and ... mesons are reconstructed in the exclusive decays B ^sup +^ [arrow right] J/[psi]K ^sup +^, B ^sup 0^ [arrow right] J/[psi]K ^sup *0^ and ..., with J/[psi] [arrow right] [mu] ^sup +^ [mu] ^sup -^, K ^sup *0^ [arrow right] K ^sup +^[pi]^sup -^ and [arrow right] K ^sup +^ K ^sup -^. The differential cross-sections are measured as functions of B meson transverse momentum p ^sub T^ and rapidity y, in the range 0 < p ^sub T^ < 40 GeV/c and 2.0 < y < 4.5. The integrated cross-sections in the same p ^sub T^ and y ranges, including charge-conjugate states, are measured to be ...where the third uncertainty arises from the pre-existing branching fraction measurements. [Figure not available: see fulltext.]

An angular analysis of the B-s(0)-> phi e(+)e(-) decay is performed using the proton-proton collision dataset collected between 2011 and 2018 by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1) at centre-of-mass energies of 7, 8 and 13 TeV. The analysis is performed in the very low dielectron invariant mass-squared region between 0.0009 and 0.2615 GeV2/c(4). The longitudinal polarisation fraction of the phi meson is measured to be less than 11.5% at 90% confidence level. The A(T)(ReCP) observable, which is related to the lepton forward-backward asymmetry, is measured to be 0.116 +/- 0.155 +/- 0.006, where the first uncertainty is statistical and the second systematic. The transverse asymmetries, A(T)((2)) and A(T)(ImCP), which are sensitive to the virtual photon polarisation, are found to be -0.045 +/- 0.235 +/- 0.014 and 0.002 +/- 0.247 +/- 0.016, respectively. The results are consistent with Standard Model predictions.

A bstract Using three- and four-body decays of D mesons produced in semileptonic b -hadron decays, precision measurements of D meson mass differences are made together with a measurement of the D 0 mass. The measurements are based on a dataset corresponding to an integrated luminosity of 1 . 0 fb −1 collected in pp collisions at 7 TeV. Using the decay D 0 → K + K − K − π + , the D 0 mass is measured to be The mass differences are measured using the D 0 → K + K − π + π − and modes.

The decays Λ b 0 → Λ c + D ¯ ( ∗ ) 0 K - and Λ b 0 → Λ c + D s ∗ - are observed for the first time, in proton-proton collision data at s = 13 Te V , corresponding to an integrated luminosity of 5.4 fb - 1 collected with the LHCb detector. Their ratios of branching fractions with respect to the Λ b 0 → Λ c + D s - mode are measured to be B Λ b 0 → Λ c + D ¯ 0 K - B Λ b 0 → Λ c + D s - = 0.1908 - 0.0034 + 0.0036 - 0.0018 + 0.0016 ± 0.0038 , B Λ b 0 → Λ c + D ¯ ∗ 0 K - B Λ b 0 → Λ c + D s - = 0.589 - 0.017 + 0.018 - 0.018 + 0.017 ± 0.012 , B Λ b 0 → Λ c + D s ∗ - B Λ b 0 → Λ c + D s - = 1.668 ± 0.022 - 0.055 + 0.061 , where the first uncertainties are statistical, the second systematic, and the third, for the Λ b 0 → Λ c + D ¯ ( ∗ ) 0 K - decays, are due to the uncertainties on the branching fractions of the D s - → K - K + π - and D ¯ 0 → K + π - decay modes. The measured branching fractions probe factorization assumptions in effective theories and provide the normalization for future pentaquark searches in Λ b 0 → Λ c + D ¯ ( ∗ ) 0 K - decay channels.

The calibration and performance of the opposite-side flavour tagging algorithms used for the measurements of time-dependent asymmetries at the LHCb experiment are described. The algorithms have been developed using simulated events and optimized and calibrated with B + → J / ψK + , B 0 → J / ψK ∗0 and B 0 → D ∗− μ + ν μ decay modes with 0.37 fb −1 of data collected in pp collisions at during the 2011 physics run. The opposite-side tagging power is determined in the B + → J / ψK + channel to be (2.10±0.08±0.24) %, where the first uncertainty is statistical and the second is systematic.

A bstract The angular distribution and differential branching fraction of the decay B + → K + μ + μ − are studied with a dataset corresponding to 1.0fb −1 of integrated luminosity, collected by the LHCb experiment. The angular distribution is measured in bins of dimuon invariant mass squared and found to be consistent with Standard Model expectations. Integrating the differential branching fraction over the full dimuon invariant mass range yields a total branching fraction of ( B + → K + μ + μ − ) = (4 . 36 ± 0 . 15 ± 0 . 18) × 10 −7 . These measurements are the most precise to date of the B + → K + μ + μ − decay.