11,298 research outputs found
Scaling functions of two-neutron separation energies of with finite range potentials
The behaviour of an Efimov excited state is studied within a three-body
Faddeev formalism for a general neutron-neutron-core system, where neutron-core
is bound and neutron-neutron is unbound, by considering zero-ranged as well as
finite-ranged two-body interactions. For the finite-ranged interactions we have
considered a one-term separable Yamaguchi potential. The main objective is to
study range corrections in a scaling approach, with focus in the exotic carbon
halo nucleus
Critical currents in Josephson junctions with macroscopic defects
The critical currents in Josephson junctions of conventional superconductors
with macroscopic defects are calculated for different defect critical current
densities as a function of the magnetic field. We also study the evolution of
the different modes with the defect position, at zero external field. We study
the stability of the solutions and derive simple arguments, that could help the
defect characterization. In most cases a reentrant behavior is seen, where both
a maximum and a minimum current exist.Comment: 17 pages with 16 figures, submitted to Supercond. Sci. Techno
Probing the Efimov discrete scaling in atom-molecule collision
The discrete Efimov scaling behavior, well-known in the low-energy spectrum
of three-body bound systems for large scattering lengths (unitary limit), is
identified in the energy dependence of atom-molecule elastic cross-section in
mass imbalanced systems. That happens in the collision of a heavy atom with
mass with a weakly-bound dimer formed by the heavy atom and a lighter one
with mass . Approaching the heavy-light unitary limit the wave
elastic cross-section will present a sequence of zeros/minima at
collision energies following closely the Efimov geometrical law. Our results
open a new perspective to detect the discrete scaling behavior from low-energy
scattering data, which is timely in view of the ongoing experiments with
ultra-cold binary mixtures having strong mass asymmetries, such as Lithium and
Caesium or Lithium and Ytterbium
Four-boson scale near a Feshbach resonance
We show that an independent four-body momentum scale drives the
tetramer binding energy for fixed trimer energy (or three-body scale
) and large scattering length (). The three- and four-body forces
from the one-channel reduction of the atomic interaction near a Feshbach
resonance disentangle and . The four-body independent
scale is also manifested through a family of Tjon-lines, with slope given by
for . There is the possibility of a new
renormalization group limit cycle due to the new scale
Universality in Four-Boson Systems
We report recent advances on the study of universal weakly bound four-boson
states from the solutions of the Faddeev-Yakubovsky equations with zero-range
two-body interactions. In particular, we present the correlation between the
energies of successive tetramers between two neighbor Efimov trimers and
compare it to recent finite range potential model calculations. We provide
further results on the large momentum structure of the tetramer wave function,
where the four-body scale, introduced in the regularization procedure of the
bound state equations in momentum space, is clearly manifested. The results we
are presenting confirm a previous conjecture on a four-body scaling behavior,
which is independent of the three-body one. We show that the correlation
between the positions of two successive resonant four-boson recombination peaks
are consistent with recent data, as well as with recent calculations close to
the unitary limit. Systematic deviations suggest the relevance of range
corrections.Comment: Accepted for publication in special issue of Few-Body Systems devoted
to the Sixth Workshop on the Critical Stability of Quantum Few-Body Systems,
October 2011, Erice, Sicily, Ital
New Measurement of the Relative Scintillation Efficiency of Xenon Nuclear Recoils Below 10 keV
Liquid xenon is an important detection medium in direct dark matter
experiments, which search for low-energy nuclear recoils produced by the
elastic scattering of WIMPs with quarks. The two existing measurements of the
relative scintillation efficiency of nuclear recoils below 20 keV lead to
inconsistent extrapolations at lower energies. This results in a different
energy scale and thus sensitivity reach of liquid xenon dark matter detectors.
We report a new measurement of the relative scintillation efficiency below 10
keV performed with a liquid xenon scintillation detector, optimized for maximum
light collection. Greater than 95% of the interior surface of this detector was
instrumented with photomultiplier tubes, giving a scintillation yield of 19.6
photoelectrons/keV electron equivalent for 122 keV gamma rays. We find that the
relative scintillation efficiency for nuclear recoils of 5 keV is 0.14, staying
constant around this value up to 10 keV. For higher energy recoils we measure a
value around 20%, consistent with previously reported data. In light of this
new measurement, the XENON10 experiment's results on spin-independent
WIMP-nucleon cross section, which were calculated assuming a constant 0.19
relative scintillation efficiency, change from cm to
cm for WIMPs of mass 100 GeV/c, and from
cm to cm for WIMPs of mass 30
GeV/c.Comment: 8 pages, 8 figure
Dimer-atom-atom recombination in the universal four-boson system
The dimer-atom-atom recombination process in the system of four identical
bosons with resonant interactions is studied. The description uses the exact
Alt, Grassberger and Sandhas equations for the four-particle transition
operators that are solved in the momentum-space framework. The dimer-dimer and
atom-trimer channel contributions to the ultracold dimer-atom-atom
recombination rate are calculated. The dimer-atom-atom recombination rate
greatly exceeds the three-atom recombination rate.Comment: 10 pages, 3 figures, accepted for publication in Few-Body System
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