3,747 research outputs found
Emergence of rotational bands in ab initio no-core configuration interaction calculations of light nuclei
The emergence of rotational bands is observed in no-core configuration
interaction (NCCI) calculations for the odd-mass Be isotopes (7<=A<=13) with
the JISP16 nucleon-nucleon interaction, as evidenced by rotational patterns for
excitation energies, quadrupole moments, and E2 transitions. Yrast and
low-lying excited bands are found. The results demonstrate the possibility of
well-developed rotational structure in NCCI calculations using a realistic
nucleon-nucleon interaction.Comment: 7 pages, 6 figures; to be published in Phys. Lett.
Confinement Phenomenology in the Bethe-Salpeter Equation
We consider the solution of the Bethe-Salpeter equation in Euclidean metric
for a qbar-q vector meson in the circumstance where the dressed quark
propagators have time-like complex conjugate mass poles. This approximates
features encountered in recent QCD modeling via the Dyson-Schwinger equations;
the absence of real mass poles simulates quark confinement. The analytic
continuation in the total momentum necessary to reach the mass shell for a
meson sufficiently heavier than 1 GeV leads to the quark poles being within the
integration domain for two variables in the standard approach. Through Feynman
integral techniques, we show how the analytic continuation can be implemented
in a way suitable for a practical numerical solution. We show that the would-be
qbar-q width to the meson generated from one quark pole is exactly cancelled by
the effect of the conjugate partner pole; the meson mass remains real and there
is no spurious qbar-q production threshold. The ladder kernel we employ is
consistent with one-loop perturbative QCD and has a two-parameter infrared
structure found to be successful in recent studies of the light SU(3) meson
sector.Comment: Submitted for publication; 10.5x2-column pages, REVTEX 4, 3
postscript files making 3 fig
K_{l3} transition form factors
The rainbow truncation of the quark Dyson-Schwinger equation is combined with
the ladder Bethe-Salpeter equation for the meson bound state amplitudes and the
dressed quark-W vertex in a manifestly covariant calculation of the K_{l3}
transition form factors and decay width in impulse approximation. With model
gluon parameters previously fixed by the chiral condensate, the pion mass and
decay constant, and the kaon mass, our results for the K_{l3} form factors and
the kaon semileptonic decay width are in good agreement with the experimental
data.Comment: 8 pages, 3 figures, Revte
Path integral Monte Carlo simulation of helium at negative pressures
Path integral Monte Carlo (PIMC) simulations of liquid helium at negative
pressure have been carried out for a temperature range from the critical
temperature to below the superfluid transition. We have calculated the
temperature dependence of the spinodal line as well as the pressure dependence
of the isothermal sound velocity in the region of the spinodal. We discuss the
slope of the superfluid transition line and the shape of the dispersion curve
at negative pressures.Comment: 6 pages, 7 figures, submitted to Physical Review B Revised: new
reference, replaced figure
N3LO NN interaction adjusted to light nuclei in ab exitu approach
We use phase-equivalent transformations to adjust off-shell properties of
similarity renormalization group evolved chiral effective field theory NN
interaction (Idaho N3LO) to fit selected binding energies and spectra of light
nuclei in an ab exitu approach. We then test the transformed interaction on a
set of additional observables in light nuclei to verify that it provides
reasonable descriptions of these observables with an apparent reduced need for
three- and many-nucleon interactions.Comment: Revised text due to journal referee comments. 6 pages, 2 figure
The no-core shell model with general radial bases
Calculations in the ab initio no-core shell model (NCSM) have conventionally
been carried out using the harmonic-oscillator many-body basis. However, the
rapid falloff (Gaussian asymptotics) of the oscillator functions at large
radius makes them poorly suited for the description of the asymptotic
properties of the nuclear wavefunction. We establish the foundations for
carrying out no-core configuration interaction (NCCI) calculations using a
basis built from general radial functions and discuss some of the
considerations which enter into using such a basis. In particular, we consider
the Coulomb-Sturmian basis, which provides a complete set of functions with a
realistic (exponential) radial falloff.Comment: 7 pages, 3 figures; presented at Horizons on Innovative Theories,
Experiments, and Supercomputing in Nuclear Physics 2012, New Orleans,
Louisiana, June 4-7, 2012; submitted to J. Phys. Conf. Se
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