USING DOUBLE CHARGE EXCHANGE REACTIONS TOWARDS 0 nu beta beta NUCLEAR MATRIX ELEMENTS

The knowledge of the nuclear matrix elements (NME) for the neutrinoless double beta decay is fundamental for neutrino physics. The NMEs indeed enter in the expression connecting the half-life of the neutrinoless double beta decay to the neutrino mass. Information on the nuclear matrix elements can be obtained by measuring the cross section of double charge exchange nuclear reactions. The basic point is that the initial and final-state wave functions in the two processes are the same and the transition operators are similar. The double charge exchange cross sections can be factorized in a nuclear structure term containing the matrix elements and a nuclear reaction factor. First pioneering experimental results for the Ca-40(O-18,Ne-18)Ar-40 reaction at 270 MeV incident energy show that such cross section factorization reasonably holds for the 0(+) to 0(+) transition to the Ar-40(gs), at least at very forward angles.