title: Ab initio calculation of the spectrum and structure of (16)O.
abstract: We present ab initio lattice calculations of the low-energy even-parity states of 16O using chiral nuclear effective field theory. We find good agreement with the empirical energy spectrum, and with the electromagnetic properties and transition rates. For the ground state, we find that the nucleons are arranged in a tetrahedral configuration of alpha clusters. For the first excited spin-0 state, we find that the predominant structure is a square configuration of alpha clusters, with rotational excitations that include the first spin-2 state.
authors.affiliation: Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44870 Bochum, Germany.
authors.forename: Evgeny
authors.initials: E
authors.lastname: Epelbaum
authors.affiliation: Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44870 Bochum, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Krebs
authors.affiliation: Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: Timo A
authors.initials: TA
authors.lastname: Lähde
authors.affiliation: Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Dean
authors.initials: D
authors.lastname: Lee
authors.affiliation: Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany and Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn, Germany and JARA-High Performance Computing, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: Ulf-G
authors.initials: UG
authors.lastname: Meissner
authors.affiliation: Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA.
authors.forename: Gautam
authors.initials: G
authors.lastname: Rupak