اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدStudy 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 observ
e 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.
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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.
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