Shedding light on nuclear aspects of neutrinoless double beta decay by heavy-ion double charge exchange reactions

Double charge-exchange reactions for the nuclear matrix elements of neutrinoless double beta decay

“…This way to represent the theory is particularly promising as it mimics the factorization of the 0νββ decay rate, with special emphasis on the NME for the two processes, which appear to be intimately linked. The results of first numerical calculations compared with experimental DCE data are very encouraging, signaling that both the absolute value and the diffraction pattern of the angular distributions are reasonably well described [40]. Final refinements are in progress, the most important one being the need to add coherently the MDCE and DSCE reaction amplitudes in order to account for their interference.…”

“…In the obtained DCE energy spectrum, shown in Fig. 1, the 40 Ar ground state is clearly separated from the not resolved doublet of 2 + states of 40 Ar at 1.460 MeV and 18 Ne at 1.887 MeV. At higher excitation energy the measured yield is spread over many overlapping states and the cross section tends to increase with excitation energy.…”

“…Furthermore in the same reference, the cross section is factorized for the first time adopting a schematic two-step reaction mechanism with realistic isovector interaction and Fermi and GT strength in the intermediate channel. A reasonable NME is extracted for the crucial 0 + → 0 + DCE transition to 40 Ar gs . This makes the ( 18 O, 18 Ne) reaction very promising to investigate the DCE response of the nuclei involved in 0νββ research.…”

“…In particular, in Ref. [26], pioneering experimental results for the 40 Ca( 18 O, 18 Ne) 40 Ar reaction at 15 MeV/u incident energy were reported. An angular range corresponding to scattering angles in the centre of mass 0 • < θ CM < 12 • was explored.…”

“…This formalism reveals a remarkable similarity of DSCE with 2νββ decay, although a much richer multipole spectrum is accessed in HI-DCE. The result of the application of such a DSCE approach to the 40 Ca( 18 O, 18 Ne) 40 Ar data is described in details in Refs. [31,37] and shown also in Fig.…”