A test of lepton universality, performed by measuring the ratio of the branching fractions of the B 0 → K * 0 µ + µ − and B 0 → K * 0 e + e − decays, R K * 0 , is presented. The K * 0 meson is reconstructed in the final state K + π − , which is required to have an invariant mass within 100 MeV/c 2 of the known K * (892) 0 mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb −1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q 2 , to be− 0.07 (stat) ± 0.03 (syst) for 0.045 < q 2 < 1.1 GeV 2 /c 4 , 0.69 + 0.11 − 0.07 (stat) ± 0.05 (syst) for 1.1 < q 2 < 6.0 GeV 2 /c 4 .The corresponding 95.4% confidence level intervals are [0.52, 0.89] and [0.53, 0.94]. The results, which represent the most precise measurements of R K * 0 to date, are compatible with the Standard Model expectations at the level of 2.1-2.3 and 2.4-2.5 standard deviations in the two q 2 regions, respectively.

We present a measurement of form-factor-independent angular observables in the decay B(0)→K*(892)(0)μ(+)μ(-). The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb(-1), collected by the LHCb experiment in pp collisions at a center-of-mass energy of 7 TeV. Four observables are measured in six bins of the dimuon invariant mass squared q² in the range 0.1

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.

A measurement is reported of the ratio of branching fractions R(J/ψ)=B(B_{c}^{+}→J/ψτ^{+}ν_{τ})/B(B_{c}^{+}→J/ψμ^{+}ν_{μ}), where the τ^{+} lepton is identified in the decay mode τ^{+}→μ^{+}ν_{μ}ν[over ¯]_{τ}. This analysis uses a sample of proton-proton collision data corresponding to 3.0  fb^{-1} of integrated luminosity recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. A signal is found for the decay B_{c}^{+}→J/ψτ^{+}ν_{τ} at a significance of 3 standard deviations corrected for systematic uncertainty, and the ratio of the branching fractions is measured to be R(J/ψ)=0.71±0.17(stat)±0.18(syst). This result lies within 2 standard deviations above the range of central values currently predicted by the standard model.

The doubly charmed baryon decay Ξ þþ cc → Ξ þ c π þ is observed for the first time, with a statistical significance of 5.9σ, confirming a recent observation of the baryon in the Λ þ c K − π þ π þ final state. The data sample used corresponds to an integrated luminosity of 1.7 fb −1 , collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV. The Ξ þþ cc mass is measured to be 3620.6 AE 1.5ðstatÞ AE 0.4ðsystÞ AE 0.3ðΞ þ c Þ MeV=c 2 and is consistent with the previous result. The ratio of branching fractions between the decay modes is measured to be ½BðΞ þþ cc → Ξ þ c π þ Þ × BðΞ þ c → pK − π þ Þ=½BðΞ þþ cc → Λ þ c K − π þ π þ Þ × BðΛ þ c → pK − π þ Þ ¼ 0.035 AE 0.009ðstatÞ AE 0.003ðsystÞ.