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Register a new userObservation of eta_b(2S) in Upsilon(2S) -> gamma eta_b(2S), eta_b(2S) -> hadrons, and Confirmation of eta_b(1S)
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The data for 9.3 million Upsilon(2S) and 20.9 million Upsilon(1S) taken with the CLEO III detector has been used to study the radiative population of states identified by their decay into twenty six different exclusive hadronic final states. In the Upsilon(2S) decays an enhancement is observed at a ~5 sigma level at a mass of 9974.6+-2.3(stat)+-2.1(syst) MeV. It is attributed to eta_b(2S), and corresponds to the Upsilon(2S) hyperfine splitting of 48.7+-2.3(stat)+-2.1(syst) MeV. In the Upsilon(1S) decays, the identification of eta_b(1S) is confirmed at a ~3 sigma level with M(eta_b(1S)) in agreement with its known value.
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We report the first evidence for the eta_b(2S) using the h_b(2P)->eta_b(2S)gamma transition and the first observation of the h_b(1P)->eta_b(1S)gamma and h_b(2P)->eta_b(1S)gamma transitions. The mass and width of the eta_b(1S) and eta_b(2S) are measured to be m_etab(1S)=(9402.4+-1.5+-1.8)MeV/c^2, m_etab(2S)=(9999.0+-3.5 +2.8-1.9)MeV/c^2 and Gamma_etab(1S)=(10.8 +4.0-3.7 +4.5-2.0)MeV. We also update the h_b(1P) and h_b(2P) mass measurements. We use a 133.4/fb data sample collected at energies near the Upsilon(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
Using data collected in the Belle experiment at the KEKB asymmetric-energy $e^+e^-$ collider we search for transitions $Upsilon(4S) rightarrow eta_b(1S)omega$, $Upsilon(5S) rightarrow eta_b(1S)omega$ and $Upsilon(5S) rightarrow eta_b(2S)omega$. No significant signals are observed and we set 90% confidence level upper limits on the corresponding visible cross sections: $0.2 ~textrm{pb}, 0.4 ~textrm{pb}$ and $1.9 ~textrm{pb}$, respectively.
Using samples of 102 million $Upsilon(1S)$ and 158 million $Upsilon(2S)$ events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the three-body final states $phi K^+ K^-$, $omega pi^+ pi^-$ and $K^{ast 0}(892) K^- pi^+ $, and to the two-body Vector-Tensor ($phi f_2(1525)$, $omega f_2(1270)$, $rho a_2(1320)$ and $K^{ast 0}(892) bar{K}_2^{ast 0}(1430) $) and Axial-vector-Pseudoscalar ($K_1(1270)^+ K^-$, $K_1(1400)^+ K^- $ and $b_1(1235)^+ pi^- $) pairs. Signals are observed for the first time in the $Upsilon(1S) to phi K^+ K^-$, $omega pi^+ pi^-$, $K^{ast 0} K^- pi^+$, $K^{ast0} K_2^{ast 0}$ and $Upsilon(2S) to phi K^+ K^-$, $K^{ast 0} K^- pi^+$ decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance less than $3sigma$. The ratios of the branching fractions of $Upsilon(2S)$ and $Upsilon(1S)$ decays into the same final state are used to test a perturbative QCD prediction for OZI suppressed bottomonium decays.
We use the method of double pole QCD sum rule which is basically a fit with two exponentials of the correlation function, where we can extract the masses and decay constants of mesons as a function of the Borel mass. We apply this method to study the mesons: $rho(1S,2S)$, $psi(1S,2S)$, $Upsilon(1S,2S)$ and $psi_t(1S,2S)$. We also present predictions for the toponiuns masses $psi_t(1S,2S)$ of m(1S)=357 GeV and m(2S)=374 GeV.
We report the observation of $Upsilon(2S)togammaeta_{b}(1S)$ decay based on analysis of the inclusive photon spectrum of $24.7$ fb$^{-1}$ of $e^+ e^-$ collisions at the $Upsilon(2S)$ center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We measure a branching fraction of $mathcal{B}(Upsilon(2S)togammaeta_{b}(1S))=(6.1^{+0.6+0.9}_{-0.7-0.6})times 10^{-4}$, and derive an $eta_{b}(1S)$ mass of $9394.8^{+2.7+4.5}_{-3.1-2.7}$ MeV/$c^{2}$, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode.
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