Observations of exotic structures in the J=ψp channel, which we refer to as charmonium-pentaquark states, in Λ 0 b → J=ψK − p decays are presented. The data sample corresponds to an integrated luminosity of 3 fb −1 acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis of the three-body final state reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J=ψp mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380 AE 8 AE 29 MeV and a width of 205 AE 18 AE 86 MeV, while the second is narrower, with a mass of 4449.8 AE 1.7 AE 2.5 MeV and a width of 39 AE 5 AE 19 MeV. The preferred J P assignments are of opposite parity, with one state having spin 3=2 and the other 5=2.

The branching fraction ratio R(D^{*})≡B(B[over ¯]^{0}→D^{*+}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]^{0}→D^{*+}μ^{-}ν[over ¯]_{μ}) is measured using a sample of proton-proton collision data corresponding to 3.0  fb^{-1} of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ}. The semitauonic decay is sensitive to contributions from non-standard-model particles that preferentially couple to the third generation of fermions, in particular, Higgs-like charged scalars. A multidimensional fit to kinematic distributions of the candidate B[over ¯]^{0} decays gives R(D^{*})=0.336±0.027(stat)±0.030(syst). This result, which is the first measurement of this quantity at a hadron collider, is 2.1 standard deviations larger than the value expected from lepton universality in the standard model.

An angular analysis of the B 0 → K *0(→ K + π −)μ + μ − decay is presented. The dataset corresponds to an integrated luminosity of 3.0 fb−1 of pp collision data collected at the LHCb experiment. The complete angular information from the decay is used to determine CP-averaged observables and CP asymmetries, taking account of possible contamination from decays with the K + π − system in an S-wave configuration. The angular observables and their correlations are reported in bins of q 2, the invariant mass squared of the dimuon system. The observables are determined both from an unbinned maximum likelihood fit and by using the principal moments of the angular distribution. In addition, by fitting for q 2-dependent decay amplitudes in the region 1.1 < q 2 < 6.0 GeV2/c 4, the zero-crossing points of several angular observables are computed. A global fit is performed to the complete set of CP-averaged observables obtained from the maximum likelihood fit. This fit indicates differences with predictions based on the Standard Model at the level of 3.4 standard deviations. These differences could be explained by contributions from physics beyond the Standard Model, or by an unexpectedly large hadronic effect that is not accounted for in the Standard Model predictions

An angular analysis and a measurement of the differential branching fraction of the decay B 0 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 < q 2 < 6 GeV 2 /c 4 , where precise theoretical calculations are available, the differential branching fraction is found to be more than 3 σ below the Standard Model predictions. The LHCb collaboration 30 IntroductionThe decay B 0 s → φµ + µ − is mediated by a b → s flavour changing neutral current (FCNC) transition. In the Standard Model (SM) it is forbidden at tree-level and proceeds via loop diagrams as shown in figure 1. In extensions of the SM, new heavy particles can appear in competing diagrams and affect both the branching fraction of the decay and the angular distributions of the final-state particles.This decay channel was first observed and studied by the CDF collaboration [1, 2] and subsequently studied by the LHCb collaboration using data collected during 2011, corresponding to an integrated luminosity of 1.0 fb −1 [3]. While the angular distributions were found to be in good agreement with SM expectations, the measured branching fraction differs from the recently updated SM prediction by 3.1 σ [4,5]. A similar trend is also seen for the branching fractions of other b → sµ + µ − processes, which tend to be lower than SM predictions [6-8].-1 - JHEP09(2015)179This paper presents an updated analysis of the decay B 0 s → φ(→ K + K − )µ + µ − using data accumulated by LHCb in pp collisions, corresponding to an integrated luminosity of 1.0 fb −1 collected during 2011 at 7 TeV and 2.0 fb −1 collected during 2012 at 8 TeV centreof-mass energy. The differential branching fraction dB(B 0 s → φµ + µ − )/dq 2 is determined as a function of q 2 , the square of the dimuon invariant mass. In addition, a three-dimensional angular analysis in cos θ l , cos θ K and Φ is performed in bins of q 2 . Here, the angle θ K (θ l ) denotes the angle of the K − (µ − ) with respect to the direction of flight of the B 0 s meson in the K + K − (µ + µ − ) centre-of-mass frame, and Φ denotes the angle between the µ + µ − and the K + K − decay planes in the B 0 s meson centre-of-mass frame. Compared to the previously published fit of the one-dimensional projections of the decay angles [3], the full three-dimensional angular fit gives improved sensitivity and allows access to more angular observables.The decay B 0 s → φµ + µ − is closely related to the decay B 0 → K * 0 µ + µ − , which has been studied extensively by LHCb [6,9, 10]. Although B 0 s meson production is suppressed with respect to the B 0 meson by the fragmentation fraction ratio f s /f d ∼ 1/4, the narrow φ resonance allows a clean selection with low background levels. Furthermore, the contribution from the S wave, w...

A search is presented for hidden-sector bosons, χ, produced in the decay B(0)→K*(892)(0)χ, with K*(892)(0)→K(+)π(-) and χ→μ(+)μ(-). The search is performed using pp-collision data corresponding to 3.0  fb(-1) collected with the LHCb detector. No significant signal is observed in the accessible mass range 214≤m(χ)≤4350  MeV, and upper limits are placed on the branching fraction product B(B(0)→K*(892)(0)χ)×B(χ→μ(+)μ(-)) as a function of the mass and lifetime of the χ boson. These limits are of the order of 10(-9) for χ lifetimes less than 100 ps over most of the m(χ) range, and place the most stringent constraints to date on many theories that predict the existence of additional low-mass bosons.