Using a new method described in Ref.[1], it is shown that for nuclear neutrinoless double beta decay in 2n mechanism, there appears a new correction term, which is absent in the conventional treatment based upon the closure approximation.

Using a new method described in Ref.[1], it is shown that for nuclear neutrinoless double beta decay in 2n mechanism, there appears a new correction term, which is absent in the conventional treatment based upon the closure approximation.