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Register a new userMeasurement of the polarisation amplitudes in B0 -> J/psi K*(892)0 decays
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An analysis of the decay B0 -> J/psi K*(892)0 is presented using data, corresponding to an integrated luminosity of 1.0fb^-1, collected in pp collisions at a centre-of-mass energy of 7TeV with the LHCb detector. The polarisation amplitudes and the corresponding phases are measured to be |A_{parallel}|^2 = 0.227 +- 0.004 (stat.) +- 0.011 (syst.), |A_{perp}|^2 = 0.201 +- 0.004 (stat.) +- 0.008 (syst.), delta_{parallel} [rad] = -2.94 +- 0.02 (stat.) +- 0.03 (syst.), delta_{perp} [rad] = 2.94 +- 0.02 (stat.) +- 0.02 (syst.). Comparing B0 -> J/psi K*(892)0 and bar{B}0 -> J/psi bar{K}*(892)0 decays, no evidence for direct CP violation is found.
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The first observation of the B0->J/psi K+K- decay is presented with a data sample corresponding to an integrated luminosity of 1.0/fb of pp collisions at a center-of-mass energy of 7 TeV collected with the LHCb detector. The branching fraction is measured to be B(B0->J/psi K+K-) = (2.53 +/- 0.31 +/- 0.19)x10^{-6}, where the first uncertainty is statistical and the second is systematic. An amplitude analysis of the final state in the B0->J/psi K+K- decay is performed to separate resonant and nonresonant contributions in the K+K- spectrum. Evidence of the a0(980) resonance is reported with statistical significance of 3.9 standard deviations. The corresponding product branching fraction is measured to be B(B0->J/psi a0(980), a0(980)->K+K-)=(4.70 +/- 3.31 +/- 0.72)x10^{-7}, yielding an upper limit of B(B0->J/psi a0(980), a0(980)->K+K-)<9.0x10^{-7} at 90% confidence level. No evidence of the resonant decay B0->J/psiphi; is found, and an upper limit on its branching fraction is set to be B(B0->J/psiphi)< 1.9x10^{-7} at 90% confidence level.
The first measurement of ${C!P}$ asymmetries in the decay ${B_s^0to J/psi overline{K}^{*}(892)^{0}}$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of $3.0,fb^{-1}$ of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of $7$ and $8,mathrm{TeV}$. Together with constraints from ${B^0to J/psi rho^0}$, the results are used to constrain additional contributions due to penguin diagrams in the ${C!P}$-violating phase ${{phi}_{s}}$, measured through ${B_s^0}$ decays to charmonium.
The time-dependent $CP$ asymmetry in $B_s^0 to J/psi K^+K^-$ decays is measured using $pp$ collision data, corresponding to an integrated luminosity of $3.0$fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of $7$ and $8$TeV. In a sample of 96 000 $B_s^0 to J/psi K^+K^-$ decays, the $CP$-violating phase $phi_s$ is measured, as well as 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. The values obtained are $phi_s = -0.058 pm 0.049 pm 0.006$ rad, $Gamma_s equiv (Gamma_{L}+Gamma_{H})/2 = 0.6603 pm 0.0027 pm 0.0015$ps$^{-1}$, and$DeltaGamma_s equiv Gamma_{L} - Gamma_{H} = 0.0805 pm 0.0091 pm 0.0032$ps$^{-1}$, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of those quantities to date. A combined analysis with $B_s^{0} to J/psi pi^+pi^-$ decays gives $phi_s = -0.010 pm 0.039 $rad. All measurements are in agreement with the Standard Model predictions. For the first time the phase $phi_s$ is measured independently for each polarisation state of the $K^+K^- $ system and shows no evidence for polarisation dependence.
Based on a $J/psi$ data sample of $7.8 times 10^6$ events at BESI, the decay of $ J/psi to bar{K}^*(892)^0 K^+ pi^-$ is studied and a low mass enhancement, which is believed not coming from the phase space effect or background, is visible in the $K^+ pi^-$ invariant mass spectrum recoiling against $bar{K}^*(892)^0$. Partial wave analysis of this channel favors this low mass enhancement being a broad $0^{+}$ resonance with the mass and width of $771^{+164}_{-221}pm 55$ MeV/c$^2$ and $220^{+225}_{-169} pm 97$ MeV/c$^2$, respectively.
A search for the decay $B^0_srightarrow J/psi K^{*0}$ with $K^{*0} rightarrow K^-pi^+$ is performed with 0.37 fb$^{-1}$ of $pp$ collisions at $sqrt{s}$ = 7 TeV collected by the LHCb experiment, finding a $Bs to Jpsi K^-pi^+$ peak of $114 pm 11$ signal events. The $K^-pi^+$ mass spectrum of the candidates in the $B^0_s$ peak is dominated by the $K^{*0}$ contribution. Subtracting the non-resonant $K^-pi^+$ component, the branching fraction of BsJpsiKst is $(4.4_{-0.4}^{+0.5} pm 0.8) times 10^{-5}$, where the first uncertainty is statistical and the second systematic. A fit to the angular distribution of the decay products yields the Kst polarization fractions $f_L = 0.50 pm 0.08 pm 0.02$ and $f_{||} = 0.19^{+0.10}_{-0.08} pm 0.02$.
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