Ab initio many-body calculations of nucleon scattering on $^{16}$O

We develop a new {\it ab initio} many-body approach\footnote{S. Quaglioni and P. Navratil, arXiv:0804.1560.} capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group method\footnote{Y. C. Tang {\it et al.}, Phys. Rep. {\bf 47}, 167 (1978); K. Langanke and H. Friedrich, Advances in Nuclear Physics, Plenum, New York, 1987.} with the {\it ab initio} no-core shell model (NCSM).\footnote{P. Navratil, J. P. Vary, and B. R. Barrett, Phys. Rev. Lett. {\bf 84}, 5728 (2000); Phys. Rev. C {\bf 62}, 054311 (2000).} In this way, we complement a microscopic-cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, while preserving Pauli principle and translational symmetry. We will present results for low-energy nucleon scattering on $^{16}$O and for $A=17$ bound states obtained using realistic nucleon-nucleon potentials. The $^{16}$O wave functions are calculated within the importance-truncated NCSM\footnote{R. Roth and P. Navratil, Phys. Rev. Lett. {\bf 99}, 092501 (2007).} that allows the use of model spaces up to $\approx 18\hbar\Omega$ and ultimately enables to reach convergence of phase-shifts and other observables. Prepared by LLNL under Contract DE-AC52-07NA27344. Support from the U.S. DOE/SC/NP (Work Proposal No. SCW0498), and from the U. S. Department of Energy Grant DE-FC02-07ER41457 is acknowledged.