58,023 research outputs found
Phase coherence length and quantum interference patterns at step edges
The accepted approximation used to describe quantum interference patterns at
steps is shown to be incorrect. As a result, electron lifetimes determined
using it are in error by a factor 2.Comment: 3 pages, 1 figur
A solvable non-conservative model of Self-Organized Criticality
We present the first solvable non-conservative sandpile-like critical model
of Self-Organized Criticality (SOC), and thereby substantiate the suggestion by
Vespignani and Zapperi [A. Vespignani and S. Zapperi, Phys. Rev. E 57, 6345
(1998)] that a lack of conservation in the microscopic dynamics of an SOC-model
can be compensated by introducing an external drive and thereby re-establishing
criticality. The model shown is critical for all values of the conservation
parameter. The analytical derivation follows the lines of Broeker and
Grassberger [H.-M. Broeker and P. Grassberger, Phys. Rev. E 56, 3944 (1997)]
and is supported by numerical simulation. In the limit of vanishing
conservation the Random Neighbor Forest Fire Model (R-FFM) is recovered.Comment: 4 pages in RevTeX format (2 Figures) submitted to PR
Relative production rates of He, Be, C in astrophysical environments
We assume an environment of neutrons and -particles of given density
and temperature where nuclear syntheses into He, Be and C
are possible. We investigate the resulting relative abundance as a function of
density and temperature. When the relative abundance of -particles
is between 0.2 and 0.9, or larger than 0.9, the largest production
is Be or C, respectively. When He is mostly
frequently produced for temperatures above about 2 GK whereas the Be
production dominates at smaller temperatures.Comment: 5 pages, 4 figure
Comment on `Series expansions from the corner transfer matrix renormalization group method: the hard-squares model'
Earlier this year Chan extended the low-density series for the hard-squares
partition function to 92 terms. Here we analyse this extended
series focusing on the behaviour at the dominant singularity which lies
on on the negative fugacity axis. We find that the series has a confluent
singularity of order 2 at with exponents and
. We thus confirm that the exponent has the exact
value as observed by Dhar.Comment: 5 pages, 1 figure, IoP macros. Expanded second and final versio
Structure and three-body decay of Be resonances
The complex-rotated hyperspherical adiabatic method is used to study the
decay of low-lying Be resonances into one neutron and two
-particles. We investigate the six resonances above the break-up
threshold and below 6 MeV: , and . The
short-distance properties of each resonance are studied, and the different
angular momentum and parity configurations of the Be and He two-body
substructures are determined. We compute the branching ratio for sequential
decay via the Be ground state which qualitatively is consistent with
measurements. We extract the momentum distributions after decay directly into
the three-body continuum from the large-distance asymptotic structures. The
kinematically complete results are presented as Dalitz plots as well as
projections on given neutron and -energy. The distributions are
discussed and in most cases found to agree with available experimental data.Comment: 12 pages, 10 figures. To appear in Physical Review
Momentum distributions from three-body decaying 9Be and 9B resonances
The complex-rotated hyperspherical adiabatic method is used to study the
decay of low-lying Be and B resonances into , and
or . We consider six low-lying resonances of Be (,
and ) and one resonance of B () to compare with. The
properties of the resonances at large distances are decisive for the momentum
distributions of the three decaying fragments. Systematic detailed energy
correlations of Dalitz plots are presented.Comment: 4 pages, 2 figures. Proceedings of the SOTANCP2 conference held in
Brussels in May 201
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