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Register a new userStudy of $eta-eta^{prime}$ mixing from measurement of $B^0_{(s)} rightarrow J/psi eta^{(prime)}$~decay rates
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A study of $B^0$~and $B^0_s$ meson decays into $J/psieta$~and $J/psieta^{prime}$ final states is performed using a data set of proton-proton collisions at centre-of-mass energies of 7 and 8TeV, collected by the LHCb experiment and corresponding to 3.0fb$^{-1}$ of integrated luminosity. The decay $B^0 rightarrow J/psi eta^{prime}$ is observed for thefirst time. The following ratios of branching fractions are measured: $$ frac{mathcal{B}(B^0 rightarrow J/psi eta^{prime})}{mathcal{B}(B^0_s rightarrow J/psi eta^{prime})} = (2.28pm0.65,(stat),pm0.10,(syst),pm0.13,(f_{s}/f_{d}))times10^{-2},$$ $$ frac{mathcal{B}(B^0 rightarrow J/psi eta)}{mathcal{B}(B^0_s rightarrow J/psi eta)} = (1.85pm0.61,(stat),pm0.09,(syst),pm0.11,(f_{s}/f_{d}))times10^{-2},$$ where the third uncertainty is related to the present knowledge of $f_{s}/f_{d}$, the ratio between the probabilities for a $b$ quark to form a $B^0_s$ or $B^0$ meson. The branching fraction ratios are used to determine the parameters of $eta-eta^{prime}$ meson mixing. In addition, the first evidence for the decay $B^0_s rightarrow psi(2S) eta^{prime}$ is reported, and the relative branching fraction is measured, $$frac{mathcal{B}(B^0_s rightarrow psi(2S) eta^{prime})}{mathcal{B}(B^0_s rightarrow J/psi eta^{prime})} = (38.7pm9.0,(stat),pm1.3,(syst),pm0.9(mathcal{B}))times10^{-2},$$ where the third uncertainty is due to the limited knowledge of the branching fractions of $J/psi$ and $psi(2S)$~mesons.
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We report the results of the first search for the decay $B_s^0 rightarrow eta^prime eta$ using $121.4~textrm{fb}^{-1}$ of data collected at the $Upsilon(5S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe no significant signal and set a 90% confidence-level upper limit of %$7.1 times 10^{-5}$ $6.5 times 10^{-5}$ on the branching fraction of this decay.
In the Standard Model (SM) charmless hadronic decays $B_s^0 rightarrow eta^prime eta$ proceed via tree-level $bto u$ and penguin $bto s$ transitions. Penguin transitions are sensitive to Beyond-the-Standard-Model (BSM) physics scenarios and could affect the branching fractions and {it CP} asymmetries in such decays. Once branching fractions for two-body decays $B_s to etaeta, etaeta^{prime}, eta^{prime}eta^{prime} $ are measured, and the theoretical uncertainties are reduced, it would be possible to extract {it CP} violating parameters from the data using the formalism based on SU(3)/U(3) symmetry. To achieve this goal, at least four of these six branching fractions need to be measured. Only the branching fraction for $B_s^0 to eta^{prime}eta^{prime}$ has been measured so far.
We measure the branching fractions of $B^{0} to J/psi eta^{(}{}{}^{)}$ decays with the complete Belle data sample of $772 times 10^{6}$ $Bbar{B}$ events collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The results for the branching fractions are: ${cal B}(B^{0} to J/psi eta)=(12.3 pm ^{1.8}_{1.7} pm 0.7) times 10^{-6}$ and ${cal B}(B^{0} to J/psieta) < 7.4 times 10^{-6}$ at 90% confidence level. The $eta-eta$ mixing angle is constrained to be less than $ 42.2^{circ}$ at 90% confidence level.
We observe the process $psi(3686) to p bar{p} eta^{prime}$ for the first time, with a statistical significance higher than 10$sigma$, and measure the branching fraction of $J/psi to p bar{p} eta^{prime}$ with an improved accuracy compared to earlier studies. The measurements are based on $4.48 times 10^8$ $psi(3686)$ and $1.31 times 10^{9}$ $J/psi$ events collected by the BESIII detector operating at the BEPCII. The branching fractions are determined to be $B(psi(3686) to p bar{p} eta^{prime}) = (1.10pm0.10pm0.08)times10^{-5}$ and $B(J/psi to p bar{p} eta^{prime})=(1.26pm0.02pm 0.07)times10^{-4}$, where the first uncertainties are statistical and the second ones systematic. Additionally, the $eta-eta^{prime}$ mixing angle is determined to be $-24^{circ} pm 11^{circ}$ based on $psi(3686) to p bar{p} eta^{prime}$, and $-24^{circ} pm 9^{circ}$ based on $J/psi to p bar{p} eta^{prime}$, respectively.
We have measured several branching ratios for $psi^prime$ decay using the data collected by FNAL E835 experiment during year 2000, obtaining ${cal B}(psi^prime to e^+ e^-) = 0.0068pm0.0001pm0.0004$, ${cal B}(psi^prime to J/psi pi^+ pi^-) = 0.292pm0.005pm0.018$, ${cal B}(psi^prime to J/psi pi^0 pi^0) = 0.167pm0.005pm0.014$ and ${cal B}(psi^prime to J/psi eta) = 0.028pm0.002pm0.002$. We also present a measurement of the dipion mass distribution in the decays $psi^prime to J/psi pi pi$.
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