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Register a new userMeasurements of branching fractions for electromagnetic transitions involving the $chi_{bJ}(1P)$ states
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Using 9.32, 5.88 million Upsilon(2S,3S) decays taken with the CLEO-III detector, we obtain five product branching fractions for the exclusive processes Upsilon(2S) => gamma chi_{b0,1,2}(1P) => gamma gamma Upsilon(1S) and Upsilon(3S) => gamma chi_{b1,2}(1P) => gamma gamma Upsilon(1S). We observe the transition chi_{b0}(1P) => gamma Upsilon(1S) for the first time. Using the known branching fractions for B[Upsilon(2S) => gamma chi_{bJ}(1P)], we extract values for B[chi_{bJ}(1P) => gamma Upsilon(1S)] for J=0, 1, 2. In turn, these values can be used to unfold the Upsilon(3S) product branching fractions to obtain values for B[Upsilon(3S) => gamma chi_{b1,2}(1P) for the first time individually. Comparison of these with each other and with the branching fraction B[Upsilon(3S) => gamma chi_{b0}] previously measured by CLEO provides tests of relativistic corrections to electric dipole matrix elements.
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We report a study of radiative decays of chi_{bJ}(1P)(J=0,1,2) mesons into 74 hadronic final states comprising charged and neutral pions, kaons, protons; out of these, 41 modes are observed with at least 5 standard deviation significance. Our measurements not only improve the previous measurements by the CLEO Collaboration but also lead to first observations in many new modes. The large sample allows us to probe the total decay width of the chi_{b0}(1P). In the absence of a statistically significant result, a 90% confidence-level upper limit is set on the width at Gamma_{total}< 2.4 MeV. Our results are based on 24.7 fb^{-1} of e+e- collision data recorded by the Belle detector at the Upsilon(2S) resonance, corresponding to (157.8pm3.6)times10^6 Upsilon(2S) decays.
Using $e^+e^-$ annihilation data taken at the CESR collider with the CLEO-c detector, measurements of two main $Omega^-$ branching fractions have been made using the reaction $psi(2S)toOmega^-overline{Omega}^+$, hyperon pair production at $sqrt{s}=3.69$~GeV, the peak of the $psi(2S)$ resonance. $Omega^-$ decay channels are identified through momentum distributions of charged particles, and systematics of the $Omega^-$ branching fractions have been studied. The result gives: $mathcal{B}(Omega^- to Lambda^0 K^-) = (68.9pm9.5pm4.3)%$, and $ mathcal{B}(Omega^- to Xi^0 pi^-) = (19.0pm4.0pm1.2)%$.
In this paper, the dilepton electromagnetic decays $chi_{cJ}(1P) to J/psi e^+e^-$ and $chi_{cJ}(1P) to Jpsi mu^+mu^-$, where $chi_{cJ}$ denotes $chi_{c0}$, $chi_{c1}$ and $chi_{c2}$, are calculated systematically in the improved Bethe-Salpeter method. The numerical results of decay widths and the invariant mass distributions of the final lepton pairs are given. The comparison is made with the recently measured experimental data of BESIII. It is shown that for the cases including $e^+e^-$, the gauge invariance is decisive and should be considered carefully. For the processes of $chi_{cJ}(1P) to J/psi e^+e^-$, the branching fraction are: $mathcal{B}[chi_{c0}(1P) to J/psi e^+e^-]=1.06^{+0.16}_{-0.18} times 10^{-4}$, $mathcal{B}[chi_{c1}(1P) to J/psi e^+e^-]=2.88^{+0.50}_{-0.53} times 10^{-3}$, and $mathcal{B}[chi_{c2}(1P) to J/psi e^+e^-]=1.74^{+0.22}_{-0.21} times 10^{-3}$. The calculated branching fractions of $chi_{cJ}(1P)to J/psi mu^+mu^-$ channels are: $mathcal{B}[chi_{c0}(1P) to J/psi mu^+mu^-]=3.80^{+0.59}_{-0.64} times 10^{-6}$, $mathcal{B}[chi_{c1}(1P) to J/psi mu^+mu^-]=2.04^{+0.36}_{-0.38} times 10^{-4}$, and $mathcal{B}[chi_{c2}(1P) to J/psi mu^+mu^-]=1.66^{+0.19}_{-0.19} times 10^{-4}$.
Using a sample of $1.06times10^{8}~psi(3686)$ events collected with the BESIII detector at BEPCII, the decays $eta_{c}(2S)to pbar{p}$ and $h_{c}to pbar{p}$ are searched for, where $eta_c(2S)$ and $h_c$ are reconstructed in the decay chains $psi(3686)togammaeta_{c}(2S)$, $eta_{c}(2S)to pbar{p}$ and $psi(3686)topi^{0}h_{c}$, $h_{c}to pbar{p}$, respectively. No significant signals are observed. The upper limits of the product branching fractions are determined to be $mathcal{B}(psi(3686)togammaeta_c(2S))timesmathcal{B}(eta_{c}(2S)to pbar{p})<1.4times10^{-6}$ and $mathcal{B}(psi(3686)topi^0h_c)timesmathcal{B}(h_{c}to pbar{p})<1.3times10^{-7}$ at the 90% C.L.. The branching fractions for $chi_{cJ}to pbar{p}$ $(J=0,~1,~2)$ are also measured to be $(24.5pm0.8pm1.3,~8.6pm0.5pm0.5,~8.4pm0.5pm0.5)times10^{-5}$, which are the worlds most precise measurements.
Using $(223.7pm1.4)times10^6$ J/$psi$ events accumulated with the BESIII detector, we study $eta_c$ decays to $phiphi$ and $omegaphi$ final states. The branching fraction of $eta_ctophiphi$ is measured to be $Br(eta_ctophiphi)=(2.5pm0.3^{+0.3}_{-0.7}pm0.6)times10^{-3}$, where the first uncertainty is statistical, the second is systematic, and the third is from the uncertainty of $Br(J/psitogammaeta_c)$. No significant signal for the double OZI-suppressed decay of $eta_ctoomegaphi$ is observed, and the upper limit on the branching fraction is determined to be $Br(eta_ctoomegaphi)<2.5times 10^{-4}$ at the 90% confidence level.
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