17,723 research outputs found
Spectra and binding energy predictions of chiral interactions for 7Li
Using the no-core shell model approach, we report on the first results for
7Li based on the next-to-next-to-leading order chiral nuclear interaction.
Both, two-nucleon and three-nucleon interactions are taken into account. We
show that the p-shell nuclei are sensitive to the subleading parts of the
chiral interactions including three-nucleon forces. Though chiral interactions
are soft, we do not observe overbinding for this p-shell nucleus and find a
realistic description for the binding energy, excitation spectrum and radius.Comment: 12 pages, 12 figure
Extrapolation Method for the No-Core Shell Model
Nuclear many-body calculations are computationally demanding. An estimate of
their accuracy is often hampered by the limited amount of computational
resources even on present-day supercomputers. We provide an extrapolation
method based on perturbation theory, so that the binding energy of a large
basis-space calculation can be estimated without diagonalizing the Hamiltonian
in this space. The extrapolation method is tested for 3H and 6Li nuclei. It
will extend our computational abilities significantly and allow for reliable
error estimates.Comment: 8 pages, 7 figures, PRC accepte
Effective Theory for Trapped Few-Fermion Systems
We apply the general principles of effective field theories to the
construction of effective interactions suitable for few- and many-body
calculations in a no-core shell model framework. We calculate the spectrum of
systems with three and four two-component fermions in a harmonic trap. In the
unitary limit, we find that three-particle results are within 10% of known
semi-analytical values even in small model spaces. The method is very general,
and can be readily extended to other regimes, more particles, different species
(e.g., protons and neutrons in nuclear physics), or more-component fermions (as
well as bosons). As an illustration, we present calculations of the
lowest-energy three-fermion states away from the unitary limit and find a
possible inversion of parity in the ground state in the limit of trap size
large compared to the scattering length. Furthermore, we investigate the lowest
positive-parity states for four fermions, although we are limited by the
dimensions we can currently handle in this case.Comment: 8 pages, 5 figure
A compact micro-wave synthesizer for transportable cold-atom interferometers
We present the realization of a compact micro-wave frequency synthesizer for
an atom interferometer based on stimulated Raman transitions, applied to
transportable inertial sensing. Our set-up is intended to address the hyperfine
transitions of Rubidium 87 atoms at 6.8 GHz. The prototype is evaluated both in
the time and the frequency domain by comparison with state-of-the-art frequency
references developed at LNE-SYRTE. In free-running mode, it features a residual
phase noise level of -65 dBrad$^2.Hz^{-1} at 10-Hz offset frequency and a white
phase noise level in the order of -120 dBrad^2.Hz^{-1} for Fourier frequencies
above 10 kHz. The phase noise effect on the sensitivity of the atomic
interferometer is evaluated for diverse values of cycling time, interrogation
time and Raman pulse duration. To our knowledge, the resulting contribution is
well below the sensitivity of any demonstrated cold atom inertial sensors based
on stimulated Raman transitions. The drastic improvement in terms of size,
simplicity and power consumption paves the way towards field and mobile
operations.Comment: accepted for publication in Review of Scientific Instruments, 6
pages, 4 figure
From non-Hermitian effective operators to large-scale no-core shell model calculations for light nuclei
No-core shell model (NCSM) calculations using ab initio effective
interactions are very successful in reproducing experimental nuclear spectra.
The main theoretical approach is the use of effective operators, which include
correlations left out by the truncation of the model space to a numerically
tractable size. We review recent applications of the effective operator
approach, within a NCSM framework, to the renormalization of the
nucleon-nucleon interaction, as well as scalar and tensor operators.Comment: To be submited to J. Phys. A, special issue on "The Physics of
Non-Hermitian Operators
Existence of a Density Functional for an Intrinsic State
A generalization of the Hohenberg-Kohn theorem proves the existence of a
density functional for an intrinsic state, symmetry violating, out of which a
physical state with good quantum numbers can be projected.Comment: 6 page
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