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Register a new userStudy of the pseudoscalar glueball in $J/psi$ radiative decays
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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.
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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.
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.
The decay $J/psi rightarrow gamma gamma phi$ is studied using a sample of $1.31 times10^{9}$ $J/psi$ events collected with the BESIII detector. Two structures around 1475 MeV/c$^2$ and 1835 MeV/c$^2$ are observed in the $gamma phi$ invariant mass spectrum for the first time. With a fit on the $gamma phi$ invariant mass, which takes into account the interference between the two structures, and a simple analysis of the angular distribution, the structure around 1475 MeV/c$^2$ is found to favor an assignment as the $eta(1475)$ and the mass and width for the structure around 1835 MeV/c$^2$ are consistent with the $X(1835)$. The statistical significances of the two structures are $13.5 sigma$ and $6.3 sigma$, respectively. The results indicate that both $eta(1475)$ and $X(1835)$ contain a sizeable $sbar{s}$ component.
In a recent measurement LHCb reported pronounced structures in the $J/psi J/psi$ spectrum. One of the various possible explanations of those is that they emerge from non-perturbative interactions of vector charmonia. It is thus important to understand whether it is possible to form a bound state of two charmonia interacting through the exchange of gluons, which hadronise into two pions at the longest distance. In this paper, we demonstrate that, given our current understanding of hadron-hadron interactions, the exchange of correlated light mesons (pions and kaons) is able to provide sizeable attraction to the di-$J/psi$ system, and it is possible for two $J/psi$ mesons to form a bound state. As a side result we find from an analysis of the data for the $psi(2S)to J/psi pipi$ transition including both $pipi$ and $Kbar K$ final state interactions an improved value for the $psi(2S)to J/psi$ transition chromo-electric polarisability: $|alpha_{psi(2S)J/psi}|= (1.8pm 0.1)~mbox{GeV}^{-3}$, where the uncertainty also includes the one induced by the final state interactions.
We use a variational technique to study heavy glueballs on gauge configurations generated with 2+1 flavours of ASQTAD improved staggered fermions. The variational technique includes glueball scattering states. The measurements were made using 2150 configurations at 0.092 fm with a pion mass of 360 MeV. We report masses for 10 glueball states. We discuss the prospects for unquenched lattice QCD calculations of the oddballs.
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