Annihilation rate of heavy 0−+ quarkonium in relativistic Salpeter method

Two-photon and two-gluon annihilation rates of ηc, ηc′, ηb and ηb′ are estimated in the relativistic Salpeter method. By solving the full Salpeter equation with a well defined relativistic wave function, we estimate Mηc=2.979±0.432GeV, Mηc′=3.566±0.437GeV, Mηb=9.364±1.120GeV and Mηb′=9.941±1.112GeV. We calculated the transition amplitude using the Mandelstam formalism and estimate the decay widths: Γ(ηc→2γ)=7.14±0.95keV, Γ(ηc′→2γ)=4.44±0.48keV, Γ(ηb→2γ)=0.384±0.047keV and Γ(ηb′→2γ)=0.191±0.025keV. We also give estimates of total widths by the two-gluon decay rates: Γtot(ηc)=19.6±2.6MeV, Γtot(ηc′)=12.1±1.3MeV, Γtot(ηb)=6.98±0.85MeV and Γtot(ηb)=3.47±0.45MeV.