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Register a new userMeasurement of the ratio of branching fractions and difference in $CP$ asymmetries of the decays $B^+to J/psipi^+$ and $B^+to J/psi K^+$
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The ratio of branching fractions and the difference in $CP$ asymmetries of the decays $B^+to J/psi pi^+$ and $B^+to J/psi K^+$ are measured using a data sample of $pp$ collisions collected by the LHCb experiment, corresponding to an integrated luminosity of $3~{{,mbox{fb}^{-1}}}$ at centre-of-mass energies of 7 and $8~mathrm{,Tekern -0.1em V}$. The results are begin{equation*} {mathcal{B}(B^+to J/psi pi^+)overmathcal{B}(B^+to J/psi K^+)}=(3.83pm0.03pm0.03)times10^{-2},, end{equation*} begin{equation*} mathcal{A}^{CP}(B^+to J/psi pi^+)-mathcal{A}^{CP}(B^+to J/psi K^+)=(1.82pm0.86pm0.14)times10^{-2}, end{equation*} where the first uncertainties are statistical and the second are systematic. Combining this result with a recent LHCb measurement of $mathcal{A}^{CP}(B^+to J/psi K^+)$ provides the most precise estimate to date of $CP$ violation in the decay $B^+to J/psi pi^+$, begin{equation*} mathcal{A}^{CP}(B^+to J/psi pi^+) =(1.91pm0.89pm0.16)times10^{-2}. end{equation*}
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The ratio of branching fractions $R_{K/pi} equiv mathcal{B}(B_{c}^{+} to J/psi K^{+})/mathcal{B}(B_{c}^{+} to J/psipi^{+})$ is measured with $pp$ collision data collected by the LHCb experiment at centre-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of 3${mbox{fb}^{-1}}$. It is found to be $ R_{K/pi} = 0.079pm0.007pm0.003$, where the first uncertainty is statistical and the second is systematic. This measurement is consistent with the previous LHCb result, while the uncertainties are significantly reduced.
A study of B+ to J/psi pi+ and B+ to psi(2S) pi+ decays is performed with data corresponding to 0.37 fb-1 of proton-proton collisions at sqrt(s)=7 TeV. Their branching fractions are found to be B(B+ to J/psi pi+) = (3.88 +- 0.11 +- 0.15) x 10^{-5} and B(B+ to psi(2S) pi+) = (2.52 +- 0.26 +- 0.15) x 10^{-5}, where the first uncertainty is related to the statistical size of the sample and the second quantifies systematic effects. The measured CP asymmetries in these modes are ACP(J/psi pi) = 0.005 +- 0.027 +- 0.011 and ACP(psi(2S) pi) = 0.048 +- 0.090 +- 0.011 with no evidence of direct CP violation seen.
The first measurement that relates semileptonic and hadronic decay rates of the $B_c^+$ meson is performed using proton-proton collision data corresponding to 1.0 fb$^{-1}$ of integrated luminosity collected with the LHCb detector. The measured value of the ratio of branching fractions, ${cal B}(B_c^+ to J/psi pi^+)/{cal B}(B_c^+to J/psimu^+ u_mu)=0.0469 pm 0.0028 (stat.) pm 0.0046 (syst.)$, is at the lower end of available theoretical predictions.
First evidence of the $B^0to J/psiomega$ decay is found and the $B_{s}^0to J/psieta$ and $B_{s}^0to J/psieta^{prime}$ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 $mathrm{fb}^{-1}$ collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of $sqrt{s} = 7$ TeV. The branching fractions of these decays are measured relative to that of the $mathrm{B}^0to J/psirho^0$ decay: $$frac{Br(B^0to J/psiomega)}{Br(B^0to J/psirho^0)} = 0.89 pm0.19(stat)^{+0.07}_{-0.13}(syst)$$ $$frac{Br(B^0_sto J/psieta)}{Br(B^0to J/psirho^0)} = 14.0 pm 1.2(stat)^{+1.1}_{-1.5}(syst)^{+1.1}_{-1.0}(frac{f_d}{f_s}),$$ $$frac{Br(B^0_sto J/psieta^{prime})}{Br(B^0to J/psirho^0)} = 12.7pm1.1(stat)^{+0.5}_{-1.3}(syst)^{+1.0}_{-0.9}(frac{f_d}{f_s}),$$ where the last uncertainty is due to the knowledge of $f_d/f_s$, the ratio of b-quark hadronization factors that accounts for the different production rate of $B^0$ and $B^0_s$ mesons. The ratio of the branching fractions of $B^0_sto J/psieta^{prime}$ and $B^0_sto J/psieta$ decays is measured to be $$ frac{Br(B^0_sto J/psieta^{prime})}{Br(B^0_sto J/psieta)} = 0.90pm0.09(stat)^{+0.06}_{-0.02}(syst).$$
We report an observation of the $B^{pm} to J/psi eta K^{pm}$ and $B^0 to J/psi eta K^0_S$ decays using 772$times 10^{6}$ $Bbar{B}$ pairs collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We obtain the branching fractions ${cal B}(B^{pm}rightarrow J/psieta K^{pm})=(1.27pm 0.11{rm (stat.)pm 0.11{rm (syst.)})}times10^{-4}$ and ${cal B}(B^0to J/psi eta K^0_S)=(5.22 pm 0.78 {rm(stat.)} pm 0.49{rm(syst.)})times10^{-5}$. We search for a new narrow charmonium(-like) state $X$ in the $J/psi eta$ mass spectrum and find no significant excess. We set upper limits on the product of branching fractions, ${cal B}(B^pm to XK^pm){cal B}(X to J/psi eta)$, at 3872 MeV$/c^2$ where a $C$-odd partner of X(3872) may exist, at $psi(4040)$ and $psi(4160)$ assuming their known mass and width, and over a range from 3.8 to 4.8 GeV$/c^2$. % at a 5 MeV$/c^2$ step. The obtained upper limits at 90% confidence level for $X^{C{rm -odd}}(3872)$, $psi(4040)$ and $psi(4160)$ are 3.8$times 10^{-6}$, 15.5$times 10^{-6}$ and 7.4$times 10^{-6}$, respectively.
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