Helicity amplitudes of the process J/ psi --> gamma theta in the glueball picture of theta(1700)

Lattice study of radiative J/ψ decay to a tensor glueball

The radiative decay of J/ψ into a pure gauge tensor glueball is studied in the quenched lattice QCD formalism. With two anisotropic lattices, the multipole amplitudes E1(0), M2(0), and E3(0) are obtained to be 0.114(12)(6) GeV, -0.011(5)(1)  GeV, and 0.023(8)(1) GeV, respectively. The first error comes from the statistics, the Q2 interpolation, and the continuum extrapolation, while the second is due to the uncertainty of the scale parameter r0(-1)=410(20)  MeV. Thus, the partial decay width Γ(J/ψ→γG(2++)) is estimated to be 1.01(22)(10) keV, which corresponds to a large branch ratio 1.1(2)(1)×10(-2). The phenomenological implication of this result is also discussed.