Questioning model-independent estimates of 2 nu beta beta decay rates

In this work we discuss the validity of recently published results, by Rumy antsev and Urin, concerning nuclear matrix elements of the two-neutrino dou ble-beta decay transitions. These authors claim that these matrix elements can be calculated in a model-independent way. We have re-analyzed their res ults and extended their formalism to account for proton-neutron correlation s at the QRPA level of approximation. We have found that the formalism fail s in describing the double beta decay observables. (C) 2000 Elsevier Scienc e B.V. All rights reserved.