Nuclear ab-initio and reaction frameworks within the gamow shell model

Abstract:
Contrary to nuclei of the valley of stability, drip-line nuclei can exhibit unique phenomena, such as the presence of a halo or particle-emission at ground state level. This arises due to the presence of cluster emission thresholds at low excitation energy, which generates important coupling to the nearby continuum. In order to take into account this feature rigorously, it is necessary to develop nuclear models unifying the degrees of freedom related to structure and reaction, as both become entangled in that region. For this, the Gamow Shell Model (GSM) has been developed. In GSM, continuum degrees of freedom are exactly taken into account through the use of basis states made of bound, resonant and scattering states, while structure is treated soundly with configuration mixing. While GSM has been utilized thoroughly for structure with effective interactions involving a core and valence particles, its extension to ab-initio and reaction frameworks have just been instigated recently. The development of a GSM ab-initio framework was indeed hindered by the appearance of very large model spaces therein. This problem has been solved using the Density Matrix Renormalization Group (DMRG), which allows to circumvent direct diagonalization of large matrices by a successive renormalization of the used many-body basis. Concerning reaction theory, the main problem for that matter was the identification of channels, which are fully mixed in GSM eigenstates. The solution to solve this conundrum has been to develop the Resonating Group Method (RGM) with GSM, so that emission channels are explicitly constructed, and then mixed by microscopically calculated potentials in a coupled-channel approach. Applications pertaining to ab-initio GSM relate to the calculation of hydrogen and helium ground states, while those of GSM-RGM involve proton elastic and inelastic scattering on light targets.

• Oral presentation