اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدA Comprehensive Study of the Radiative Decays of $J/psi$ and $psi(2S)$ to Pseudoscalar Meson Pairs, and Search for Glueballs
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Using 53 pb$^{-1}$ of $e^+e^-$ annihilation data taken at $sqrt{s}=3.686$ GeV, a comprehensive study has been made of the radiative decays of samples of 5.1 million $J/psi$ and 24.5 million $psi(2S)$ into pairs of pseudoscalar mesons, $pi^+pi^-$, $pi^0pi^0$, $K^+K^-$, $K_S^0K_S^0$, and $etaeta$. Product branching fractions for the radiative decays of $J/psi$ and $psi(2S)$ to scalar resonances $f_0(1370,1500,1710,2100, text{and} 2200)$, and tensor resonances $f_2(1270,1525, text{and} 2230)$ have been determined, and are discussed in relation to predicted glueballs. For $psi(2S)$ radiative decays the search for glueballs has been extended to masses between 2.5 GeV and 3.3 GeV.
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Using a sample of $4.48times10^{8}$ $psi(3686)$ events collected with the BESIII detector at the BEPCII collider, we study the two-photon decays of the pseudoscalar mesons $pi^0$, $eta$, $eta^prime$, $eta(1405)$, $eta(1475)$, $eta(1760)$, and $X(1835
)$ in $J/psi$ radiative decays using $psi(3686)topi^{+}pi^{-}J/psi$ events. The $pi^0$, $eta$ and $eta^prime$ mesons are clearly observed in the two-photon mass spectra, and the branching fractions are determined to be $B(J/psitogammapi^{0}to3gamma)=(3.57pm0.12pm0.16)times10^{-5}$, $B(J/psitogammaetato3gamma)=(4.42pm0.04pm0.18)times10^{-4}$, and $B(J/psitogammaetato3gamma)=(1.26pm0.02pm0.05)times10^{-4}$, where the first errors are statistical and the second systematic. No clear signal for $eta(1405)$, $eta(1475)$, $eta(1760)$ or $X(1835)$ is observed in the two-photon mass spectra, and upper limits at the $90%$ confidence level on the product branching fractions are obtained.
We aim to explore the production rate of the pseudoscalar glueball in $J/psi$ radiative decay by lattice QCD in quenched approximation. The calculation is performed on three anisotropic lattices with the spatial lattice spacing ranging from 0.222(2)
fm to 0.110(1) fm. As a calibration of some systematical uncertainties, we first extract the $M1$ form factor $hat{V}(0)$ of the process $J/psitogammaeta_{c}$ and get the result $hat{V}(0)=1.933(41)$ in the continuum limit, which gives the partial width $Gamma(J/psitogammaeta_{c})=2.47(11)$ keV. These results are in agreement with that of previous lattice studies. As for the pseudoscalar glueball $G_{0^{-+}}$, its mass is derived to be $2.395(14)$ GeV, and the form factor $hat{V}(0)$ of the process $J/psitogamma G_{0^{-+}}$ is determined to be $hat{V}(0)=0.0246(43)$ after continuum extrapolation. Finally, the production rate of the pseudoscalar glueball is predicted to be $2.31(90)times10^{-4}$, which is much smaller than that of conventional light $qbar{q}$ $eta$ states. After the subtraction of the phase space factor, the couplings of $J/psi Xgamma$ are similar where $X$ stands for $eta$ states and the pseudoscalar glueball. Possibly, the $U_{A}(1)$ anomaly plays an important role for the large couplings of gluons to the flavor singlet $eta$ states in $J/psi$ radiative decays.
We measure the mass of the eta meson using psi(2S) --> eta J/psi events acquired with the CLEO-c detector operating at the CESR e+e- collider. Using the four decay modes eta --> gamma gamma, 3pi0, pi+pi-pi0, and pi+pi-gamma, we find M(eta)=547.785 +-
0.017 +- 0.057 MeV, in which the first uncertainty is statistical and the second systematic. This result has an uncertainty comparable to the two most precise previous measurements and is consistent with that of NA48, but is inconsistent at the level of 6.5sigma with the much smaller mass obtained by GEM.
With a sample of 14 million psi(2S) events collected by the BESII detector at the Beijing Electron Positron Collider (BEPC), the decay channels psi(2S)->p p-bar, Lambda Lambda-bar, Sigma0 Sigma0-bar, Xi Xi-bar are measured, and their branching ratios
are determined to be (3.36+-0.09+-0.24)*10E-4, (3.39+-0.20+-0.32)*10E-4, (2.35+-0.36+-0.32)*10E-4, (3.03+-0.40+-0.32)*10E-4, respectively. In the decay psi(2S)->p p-bar, the angular distribution parameter alpha is determined to be 0.82+-0.17+-0.04.
Using the data samples of $1.31times 10^9$ $J/psi$ events and $4.48times 10^8$ $psi(3686)$ events collected with the BESIII detector, partial wave analyses on the decays $J/psi$ and $psi(3686) to pi^+pi^-eta^prime$ are performed with a relativistic c
ovariant tensor amplitude approach. The dominant contribution is found to be $J/psi$ and $psi(3686)$ decays to $rhoeta^prime$. In the $J/psi$ decay, the branching fraction ${cal B}(J/psito rhoeta^prime)$ is determined to be $(7.90pm0.19(mathrm{stat})pm0.49(mathrm{sys}))times 10^{-5}$. Two solutions are found in the $psi(3686)$ decay, and the corresponding branching fraction ${cal B}(psi(3686)to rhoeta^prime)$ is $(1.02pm0.11(mathrm{stat})pm0.24(mathrm{sys}))times 10^{-5}$ for the case of constructive interference, and $(5.69pm1.28(mathrm{stat})pm2.36(mathrm{sys}))times 10^{-6}$ for destructive interference. As a consequence, the ratios of branching fractions between $psi(3686)$ and $J/psi$ decays to $rhoeta^prime$ are calculated to be $(12.9pm1.4(mathrm{stat})pm3.1(mathrm{sys}))$% and $(7.2pm1.6(mathrm{stat})pm3.0(mathrm{sys}))$%, respectively. We also determine the inclusive branching fractions of $J/psi$ and $psi(3686)$ decays to $pi^+pi^-eta^prime$ to be $(1.36pm0.02(mathrm{stat})pm0.08(mathrm{sys}))times 10^{-4}$ and $(1.51pm0.14(mathrm{stat})pm 0.23(mathrm{sys}))times 10^{-5}$, respectively.
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