The etasub(c) → 2#betta# decay and power correction

The power corrections to etasub(c) → 2#betta#-decay are estimated in the framework of the sum rules QSD. It is clear that the power corrections to etasub(c) → 2#betta# come only from the gluon condensate. This is due to the fact that for heavy quark operator < anti psisub(c)psisub(c)> approximately 1/msub(c) and hence the contribution of quark condensate is suppressed. Obtained are that decay width is GITA(etasub(c) → 2#betta#) = (6.4R +-0.64) keV. For comparison reminded are that without power corrections the decay width GITA(etasub(c) → 2#betta#) approximately 6 keV. From this it follows that the power corrections to the etasub(c) → 2#betta# decay width are of the order of 10%