Model-independent evidence for $J/psi p$ contributions to $Lambda_b^0to J/psi p K^-$ decays

The data sample of $Lambda_b^0to J/psi p K^-$ decays acquired with the LHCb detector from 7 and 8~TeV $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$, is inspected for the presence of $J/psi p$ or $J/psi K^-$ contributions with minimal assumptions about $K^- p$ contributions. It is demonstrated at more than 9 standard deviations that $Lambda_b^0to J/psi p K^-$ decays cannot be described with $K^- p$ contributions alone, and that $J/psi p$ contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for $P_c^+to J/psi p$ charmonium-pentaquark states in the same data sample.

Observation of $J/psi p$ resonances consistent with pentaquark states in ${Lambda_b^0to J/psi K^-p}$ decays

Observations of exotic structures in the $J/psi p$ channel, that we refer to as pentaquark-charmonium states, in $Lambda_b^0to J/psi K^- p$ decays are presented. The data sample corresponds to an integrated luminosity of 3/fb acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis is performed on the three-body final-state that reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the $J/psi p$ 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 $4380pm 8pm 29$ MeV and a width of $205pm 18pm 86$ MeV, while the second is narrower, with a mass of $4449.8pm 1.7pm 2.5$ MeV and a width of $39pm 5pm 19$ MeV. The preferred $J^P$ assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.

Measurement of the $B_s^0to J/psi K_S^0$ branching fraction

The $B_s^0to J/psi K_S^0$ branching fraction is measured in a data sample corresponding to 0.41$fb^{-1}$ of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to the penguin contributions affecting the sin2$beta$ measurement from $B^0to J/psi K_S^0$ The time-integrated branching fraction is measured to be $BF(B_s^0to J/psi K_S^0)=(1.83pm0.28)times10^{-5}$. This is the most precise measurement to date.

Study of $J/psi$ and $psi(3686)$ decay to $Lambdabar{Lambda}$ and $Sigma^0bar{Sigma}^0$ final states

Using $1310.6times10^6$ $J/psi$ and $447.9times10^6$ $psi(3686)$ events collected with the BESIII detector at the BEPCII $e^{+}e^{-}$ collider, the branching fractions and the angular distributions of $J/psi$ and $psi(3686)$ decays to $Lambdabar{Lambda}$ and $Sigma^0bar{Sigma}^0$ final states are measured. The branching fractions are in agreement with, and much more precise than, the averages of previously published results. The polar angular distributions of $psi(3686)$ decays are measured for the first time, while those of $J/psi$ decays are measured with much improved precision. In addition, the ratios of branching fractions $frac{mathcal{B}(psi(3686)toLambdabar{Lambda})}{mathcal{B}(J/psitoLambdabar{Lambda})}$ and $frac{mathcal{B}(psi(3686)toSigma^0bar{Sigma}^0)}{mathcal{B}(J/psitoSigma^0bar{Sigma}^0)}$ are determined to test the 12% rule.

Measurement of CP violation and the B_s^0 meson decay width difference with B_s^0to J/psi K^+ K^- and B_s^0to J/psipi^+pi^- decays

The time-dependent CP asymmetry in B_s^0to J/psi K^+K^- decays is measured using $pp$ collision data at sqrt{s}=7TeV, corresponding to an integrated luminosity of 1.0fb^-1, collected with the LHCb detector. The decay time distribution is characterised by the decay widths Gamma_L and Gamma_H of the light and heavy mass eigenstates of the B_s^0--bar{B}_s^0 system and by a CP-violating phase phi_s. In a sample of 27,617 B_s^0to J/psi K^+K^- decays, where the dominant contribution comes from B_s^0to J/psiphi decays, these parameters are measured to be phi_s = 0.07 pm 0.09 (stat) pm 0.01 (syst) rad, Gamma_s equiv (Gamma_L+Gamma_H)/2 = 0.663 pm 0.005 (stat) pm 0.006 (syst) ps^-1, DeltaGamma_s equiv Gamma_L -Gamma_H = 0.100 pm 0.016 (stat) pm 0.003 (syst) & ps^-1, corresponding to the single most precise determination of phi_s, DeltaGamma_s and Gamma_s. The result of performing a combined analysis with B_s^{0} to J/psi pi^+pi^- decays gives phi_s = 0.01 pm 0.07 (stat) pm 0.01 (syst) rad, Gamma_s = 0.661 pm 0.004 (stat) pm 0.006 (syst) ps^-1, DeltaGamma_s = 0.106 pm 0.011 (stat) pm 0.007 (syst) & ps^-1. All measurements are in agreement with the Standard Model predictions.