Predictive power for superheavy nuclear mass and possible stability beyond the neutron drip line in deformed relativistic Hartree-Bogoliubov theory in continuum

Predictive power of the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) for nuclear mass is examined in the superheavy region $102 \le Z \le 120$. The accuracy to predict the 10 (56) measured (measured and empirical) masses is $0.635$ ($0.642$) MeV, which is in comparison with $0.515$ ($1.360$) MeV by WS4 and $0.910$ ($2.831$) MeV by FRDM. Possible stability against multi-neutron emission beyond the two-neutron drip line is explored by the DRHBc theory, which takes into account simultaneously the deformation effects, the pairing correlations, and the continuum effects. Nuclei stable against two- and multi-neutron emissions beyond the two-neutron drip line are predicted in $_{106}$Sg, $_{108}$Hs, $_{110}$Ds, and $_{112}$Cn isotopic chains, forming a peninsula of stability adjacent to the nuclear mainland. This stability is mainly due to the deformation which significantly affects the shell structure around the Fermi surface. The pairing correlations and continuum influence the stability peninsula in a self-consistent way.