2,209 research outputs found
Can Modern Nuclear Hamiltonians Tolerate a Bound Tetraneutron?
I show that it does not seem possible to change modern nuclear Hamiltonians
to bind a tetraneutron without destroying many other successful predictions of
those Hamiltonians. This means that, should a recent experimental claim of a
bound tetraneutron be confirmed, our understanding of nuclear forces will have
to be significantly changed. I also point out some errors in previous
theoretical studies of this problem.Comment: 4 pages, 4 figures Revision corrects a pronou
Ab initio calculation of the electromagnetic and neutral-weak response functions of 4He and 12C
Precise measurement of neutrino oscillations, and hence the determination of
their masses demands a quantitative understanding of neutrino-nucleus
interactions. To this aim, two-body meson-exchange currents have to be
accounted for along within realistic models of nuclear dynamics. We summarize
our progresses towards the construction of a consistent framework, based on
quantum Monte Carlo methods and on the spectral function approach, that can be
exploited to accurately describe neutrino interactions with atomic nuclei over
the broad kinematical region covered by neutrino experiments.Comment: 8 pages, 4 figure, Proceedings of the 21st International Conference
on Few-Body Problems in Physics, Chicago, Illinois, US
Benchmarks of the full configuration interaction, Monte Carlo shell model, and no-core full configuration methods
We report no-core solutions for properties of light nuclei with three
different approaches in order to assess the accuracy and convergence rates of
each method. Full configuration interaction (FCI), Monte Carlo shell model
(MCSM) and no core full configuration (NCFC) approaches are solved separately
for the ground state energy and other properties of seven light nuclei using
the realistic JISP16 nucleon-nucleon interaction. The results are consistent
among the different approaches. The methods differ significantly in how the
required computational resources scale with increasing particle number for a
given accuracy.Comment: 19 pages, 14 figures, 6 table
Walking the Maternal Tightrope: Work and Family in America
In the last few decades, an unprecedented number of women with children have entered the U.S. workforce. The ability to negotiate the roles of parent and employee is important to the health and financial well-being of these women and their families, but institutional and social barriers impede the process. Using the empirical and theoretical literature on women and work, this article examines these barriers. The authors address the impact of cultural ideals, psychological processes, and public policy on the maternal work-family balance. Several changes that would help create an atmosphere supportive of balance are explored, including increased support for shared parenting and improvements to the Family and Medical Leave Act
Nuclear spin-orbit interaction from chiral pion-nucleon dynamics
Using the two-loop approximation of chiral perturbation theory, we calculate
the momentum and density dependent nuclear spin-orbit strength .
This quantity is derived from the spin-dependent part of the interaction energy
of a nucleon scattering off weakly inhomogeneous isospin
symmetric nuclear matter. We find that iterated -exchange generates at
saturation density, MeV, a spin-orbit strength at of
MeVfm in perfect agreement with the empirical
value used in the shell model. This novel spin-orbit strength is neither of
relativistic nor of short range origin. The potential underlying the
empirical spin-orbit strength becomes a
rather weak one, MeV, after the identification as suggested by the present calculation. We observe however a
strong -dependence of leading even to a sign change above
MeV. This and other features of the emerging spin-orbit Hamiltonian
which go beyond the usual shell model parametrization leave questions about the
ultimate relevance of the spin-orbit interaction generated by -exchange
for a finite nucleus. We also calculate the complex-valued isovector
single-particle potential in isospin asymmetric
nuclear matter proportional to . For the real part we find
reasonable agreement with empirical values and the imaginary part vanishes at
the Fermi-surface .Comment: 20 pages, 10 Figures, Accepted for publication in Nuclear Physics
Resonant Photon-Assisted Tunneling Through a Double Quantum Dot: An Electron Pump From Spatial Rabi Oscillations
The time average of the fully nonlinear current through a double quantum dot,
subject to an arbitrary combination of ac and dc voltages, is calculated
exactly using the Keldysh nonequilibrium Green function technique. When driven
on resonance, the system functions as an efficient electron pump due to Rabi
oscillation between the dots. The pumping current is maximum when the coupling
to the leads equals the Rabi frequency.Comment: 6 pages, REVTEX 3.0, 3 postscript figure
Time-Dependent Current Partition in Mesoscopic Conductors
The currents at the terminals of a mesoscopic conductor are evaluated in the
presence of slowly oscillating potentials applied to the contacts of the
sample. The need to find a charge and current conserving solution to this
dynamic current partition problem is emphasized. We present results for the
electro-chemical admittance describing the long range Coulomb interaction in a
Hartree approach. For multiply connected samples we discuss the symmetry of the
admittance under reversal of an Aharonov-Bohm flux.Comment: 22 pages, 3 figures upon request, IBM RC 1971
Matter and charge radius of 6He in the hyperspherical-harmonics approach
We present ab-initio calculations of the binding energy and radii of the
two-neutron halo nucleus 6He using two-body low-momentum interactions based on
chiral effective field theory potentials. Calculations are performed via a
hyperspherical harmonics expansion where the convergence is sped up introducing
an effective interaction for non-local potentials. The latter is essential to
reach a satisfactory convergence of the extended matter radius and of the
point-proton radius. The dependence of the results on the resolution scale is
studied. A correlation is found between the radii and the two-neutron
separation energy. The importance of three-nucleon forces is pointed out
comparing our results and previous calculations to experiment.Comment: 8 pages, 6 figures, minor changes, published versio
Local three-nucleon interaction from chiral effective field theory
The three-nucleon (NNN) interaction derived within the chiral effective field
theory at the next-to-next-to-leading order (N2LO) is regulated with a function
depending on the magnitude of the momentum transfer. The regulated NNN
interaction is then local in the coordinate space, which is advantages for some
many-body techniques. Matrix elements of the local chiral NNN interaction are
evaluated in a three-nucleon basis. Using the ab initio no-core shell model
(NCSM) the NNN matrix elements are employed in 3H and 4He bound-state
calculations.Comment: 17 pages, 9 figure
- …