9,709 research outputs found
Comment on Gauge-Independent Analysis of Chern-Simons Theory with Matter Coupling
It is shown that a recently proposed relativistic field theory of anyons is
mathematically flawed and also does not satisfy reasonable criteria for such a
theory.Comment: 4 page
Efimov Physics around the neutron rich Calcium-60 isotope
We calculate the neutron-Calcium-60 S-wave scattering phase shifts using
state of the art coupled-cluster theory combined with modern ab initio
interactions derived from chiral effective theory. Effects of three-nucleon
forces are included schematically as density dependent nucleon-nucleon
interactions. This information is combined with halo effective field theory in
order to investigate the Calcium-60-neutron-neutron system. We predict
correlations between different three-body observables and the two-neutron
separation energy of Calcium-62. This provides evidence of Efimov physics along
the Calcium isotope chain. Experimental key observables that facilitate a test
of our findings are discussed.Comment: 5 pages, 4 figure
Gamow shell-model calculations of drip-line oxygen isotopes
We employ the Gamow shell model (GSM) to describe low-lying states of the
oxygen isotopes 24O and 25O. The many-body Schrodinger equation is solved
starting from a two-body Hamiltonian defined by a renormalized low-momentum
nucleon-nucleon (NN) interaction, and a spherical Berggren basis. The Berggren
basis treats bound, resonant, and continuum states on an equal footing, and is
therefore an appropriate representation of loosely bound and unbound nuclear
states near threshold. We show that such a basis is necessary in order to
obtain a detailed and correct description of the low-lying 1+ and 2+ excited
states in 24O. On the other hand, we find that a correct description of binding
energy systematics of the ground states is driven by proper treatment and
inclusion of many-body correlation effects. This is supported by the fact that
we get 25O unstable with respect to 24O in both oscillator and Berggren
representations starting from a 22O core. Furthermore, we show that the
structure of these loosely bound or unbound isotopes are strongly influenced by
the 1S0 component of the NN interaction. This has important consequences for
our understanding of nuclear stability.Comment: 5 pages, 3 figure
Generalized contour deformation method in momentum space: two-body spectral structures and scattering amplitudes
A generalized contour deformation method (GCDM) which combines complex
rotation and translation in momentum space, is discussed. GCDM gives accurate
results for bound, virtual (antibound), resonant and scattering states starting
with a realistic nucleon-nucleon interaction. It provides a basis for full
off-shell -matrix calculations both for real and complex input energies.
Results for both spectral structures and scattering amplitudes compare
perfectly well with exact values for the separable Yamaguchi potential.
Accurate calculation of virtual states in the Malfliet-Tjon and the realistic
CD-Bonn nucleon-nucleon interactions are presented.
GCDM is also a promising method for the computation of in-medium properties
such as the resummation of particle-particle and particle-hole diagrams in
infinite nuclear matter. Implications for in-medium scattering are discussed.Comment: 15 pages, revte
Ab-initio coupled-cluster effective interactions for the shell model: Application to neutron-rich oxygen and carbon isotopes
We derive and compute effective valence-space shell-model interactions from
ab-initio coupled-cluster theory and apply them to open-shell and neutron-rich
oxygen and carbon isotopes. Our shell-model interactions are based on
nucleon-nucleon and three-nucleon forces from chiral effective-field theory. We
compute the energies of ground and low-lying states, and find good agreement
with experiment. In particular our calculations are consistent with the N=14,
16 shell closures in oxygen-22 and oxygen-24, while for carbon-20 the
corresponding N=14 closure is weaker. We find good agreement between our
coupled-cluster effective-interaction results with those obtained from standard
single-reference coupled-cluster calculations for up to eight valence neutrons
- …