Angular analysis and differential branching fraction of the decay B {/s 0} → ϕμ + μ -

An angular analysis and a measurement of the differential branching fraction of the decay B0 s → φµ+µ − are presented, using data corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions recorded by the LHCb experiment at √ s = 7 and 8 TeV. Measurements are reported as a function of q 2 , the square of the dimuon invariant mass and results of the angular analysis are found to be consistent with the Standard Model. In the range 1 < q2 < 6 GeV2/c4 , where precise theoretical calculations are available, the differential branching fraction is found to be more than 3 σ below the Standard Model predictions

Observation of the B0 →ρ0ρ0 decay from an amplitude analysis of B0 → (π+π-) (π+π-) decays

Proton-proton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb−1 , are analysed to search for the charmless B0 → ρ 0ρ 0 decay. More than 600 B0 → (π +π −)(π +π −) signal decays are selected and used to perform an amplitude analysis, under the assumption of no CP violation in the decay, from which the B0 → ρ 0ρ 0 decay is observed for the first time with 7.1 standard deviations significance. The fraction of B0 → ρ 0ρ 0 decays yielding a longitudinally polarised final state is measured to be fL = 0.745+0.048 −0.058(stat) ± 0.034(syst). The B0 → ρ 0ρ 0 branching fraction, using the B0 → φK∗ (892)0 decay as reference, is also reported as B(B0 → ρ 0ρ 0 ) = (0.94 ± 0.17(stat) ± 0.09(syst) ± 0.06(BF)) × 10−6

Searches for Λ0b and Ξ0b decays to K0Spπ− and K0SpK− final states with first observation of the Λ0b→K0Spπ− decay

A search for previously unobserved decays of beauty baryons to the final states K0 S pπ− and K0 S pK− is reported. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb−1 of pp collisions. The Λ 0 b → K0pπ− decay is observed with a significance of 8.6 σ, with branching fraction B(Λ 0 b → K0 pπ−) = (1.26 ± 0.19 ± 0.09 ± 0.34 ± 0.05) × 10−5 , where the uncertainties are statistical, systematic, from the ratio of fragmentation fractions fΛ0 b /fd, and from the branching fraction of the B0→ K0π +π − normalisation channel, respectively. A first measurement is made of the CP asymmetry, giving ACP (Λ 0 b → K0 pπ−) = 0.22 ± 0.13 (stat) ± 0.03 (syst). No significant signals are seen for Λ 0 b → K0 S pK− decays, Ξ0 b decays to both the K0 S pπ− and K0 S pK− final states, and the Λ 0 b → D− s (→ K0 SK−)p decay, and upper limits on their branching fractions are reported

Observation of Z production in proton-lead collisions at LHCb

The first observation of Z boson production in proton-lead collisions at a centreof-mass energy per proton-nucleon pair of √ sNN = 5 TeV is presented. The data sample corresponds to an integrated luminosity of 1.6 nb−1 collected with the LHCb detector. The Z candidates are reconstructed from pairs of oppositely charged muons with pseudorapidities between 2.0 and 4.5 and transverse momenta above 20 GeV/c. The invariant dimuon mass is restricted to the range 60 − 120 GeV/c2 . The Z production cross-section is measured to be σZ→µ+µ− (fwd) = 13.5 +5.4 −4.0 (stat.) ± 1.2(syst.) nb in the direction of the proton beam and σZ→µ+µ− (bwd) = 10.7 +8.4 −5.1 (stat.) ± 1.0(syst.) nb in the direction of the lead beam, where the first uncertainty is statistical and the second systematic

Dalitz plot analysis of B0→D¯0π+π- decays

The resonant substructures of B0 → D0π +π − decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions collected by the LHCb detector is used. The branching fraction of the B0 → D0π +π − decay in the region m(D0π ±) > 2.1 GeV/c2 is measured to be (8.46 ± 0.14 ± 0.29 ± 0.40) × 10−4 , where the first uncertainty is statistical, the second is systematic and the last arises from the normalisation channel B0 → D∗ (2010)−π +. The π +π − S-wave components are modelled with the Isobar and K-matrix formalisms. Results of the Dalitz plot analyses using both models are presented. A resonant structure at m(D0π −) ≈ 2.8 GeV/c2 is confirmed and its spin-parity is determined for the first time as J P = 3−. The branching fraction, mass and width of this structure are determined together with those of the D∗ 0 (2400)− and D∗ 2 (2460)− resonances. The branching fractions of other B0 → D0h 0 decay components with h 0 → π +π − are also reported. Many of these branching fraction measurements are the most precise to date. The first observation of the decays B0 → D0f0(500), B0 → D0f0(980), B0 → D0ρ(1450), B0 → D∗ 3 (2760)−π + and the first evidence of B0 → D0f0(2020) are presented

Quantum numbers of the X (3872 ) state and orbital angular momentum in its ρ0J /ψ decay

Angular correlations in B+ → X(3872)K+ decays, with X(3872) → ρ 0J/ψ, ρ 0 → π +π − and J/ψ → µ +µ −, are used to measure orbital angular momentum contributions and to determine the J P C value of the X(3872) meson. The data correspond to an integrated luminosity of 3.0 fb−1 of proton-proton collisions collected with the LHCb detector. This determination, for the first time performed without assuming a value for the orbital angular momentum, confirms the quantum numbers to be J P C = 1++. The X(3872) is found to decay predominantly through S wave and an upper limit of 4% at 95% C.L. is set on the D-wave contribution

Differential branching fraction and angular analysis of the decay B0→K∗0μ+μ−

The angular distribution and differential branching fraction of the decay B 0→ K ∗0 μ + μ − are studied using a data sample, collected by the LHCb experiment in pp collisions at s√=7 TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions

Measurements of the branching fractions of B+→ppK+ decays

The branching fractions of the decay B+ → pp̄K+ for different intermediate states are measured using data, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment. The total branching fraction, its charmless component Mpp̄ < 2.85 GeV/c2 and the branching fractions via the resonant cc̄ states η c(1S) and ψ(2S) relative to the decay via a J/ψ intermediate state are [Equation not available: see fulltext.] Upper limits on the B + branching fractions into the η c(2S) meson and into the charmonium-like states X(3872) and X(3915) are also obtained

Search for the decay Bs0→D*∓π±

A search for the decay Bs0→D*∓π± is presented using a data sample corresponding to an integrated luminosity of 1.0  fb-1 of pp collisions collected by LHCb. This decay is expected to be mediated by a W-exchange diagram, with little contribution from rescattering processes, and therefore a measurement of the branching fraction will help us to understand the mechanism behind related decays such as Bs0→π+π- and Bs0→DD- . Systematic uncertainties are minimized by using B0→D*∓π± as a normalization channel. We find no evidence for a signal, and set an upper limit on the branching fraction of B(Bs0→D*∓π±)<6.1(7.8)×10-6 at 90% (95%) confidence level

Observation of two new Ξb−\Xi_b^- baryon resonances

Two structures are observed close to the kinematic threshold in the $\Xi_b^0 \pi^-$ mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb$^{-1}$ recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content $bds$ are expected in this mass region: the spin-parity $J^P = \frac{1}{2}^+$ and $J^P=\frac{3}{2}^+$ states, denoted $\Xi_b^{\prime -}$ and $\Xi_b^{*-}$. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be $m(\Xi_b^{\prime -}) - m(\Xi_b^0) - m(\pi^{-}) = 3.653 \pm 0.018 \pm 0.006$ MeV$/c^2$, $m(\Xi_b^{*-}) - m(\Xi_b^0) - m(\pi^{-}) = 23.96 \pm 0.12 \pm 0.06$ MeV$/c^2$, $\Gamma(\Xi_b^{*-}) = 1.65 \pm 0.31 \pm 0.10$ MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of $\Gamma(\Xi_b^{\prime -}) < 0.08$ MeV at 95% confidence level. Relative production rates of these states are also reported.Comment: 17 pages, 2 figure