18,592 research outputs found
Rejuvenation and Memory in model Spin Glasses in 3 and 4 dimensions
We numerically study aging for the Edwards-Anderson Model in 3 and 4
dimensions using different temperature-change protocols. In D=3, time scales a
thousand times larger than in previous work are reached with the SUE machine.
Deviations from cumulative aging are observed in the non monotonic time
behavior of the coherence length. Memory and rejuvenation effects are found in
a temperature-cycle protocol, revealed by vanishing effective waiting times.
Similar effects are reported for the D=3$site-diluted ferromagnetic Ising model
(without chaos). However, rejuvenation is reduced if off-equilibrium
corrections to the fluctuation-dissipation theorem are considered. Memory and
rejuvenation are quantitatively describable in terms of the growth regime of
the spin-glass coherence length.Comment: Extended protocols. Accepted in Phys. Rev. B. 10 postscript figure
Phenomenology of SUSY with scalar sequestering
The defining feature of scalar sequestering is that the MSSM squark and
slepton masses as well as all entries of the scalar Higgs mass matrix vanish at
some high scale. This ultraviolet boundary condition - scalar masses vanish
while gaugino and Higgsino masses are unsuppressed - is independent of the
supersymmetry breaking mediation mechanism. It is the result of renormalization
group scaling from approximately conformal strong dynamics in the hidden
sector. We review the mechanism of scalar sequestering and prove that the same
dynamics which suppresses scalar soft masses and the B_mu term also drives the
Higgs soft masses to -|mu|^2. Thus the supersymmetric contribution to the Higgs
mass matrix from the mu-term is exactly canceled by the soft masses. Scalar
sequestering has two tell-tale predictions for the superpartner spectrum in
addition to the usual gaugino mediation predictions: Higgsinos are much heavier
(mu > TeV) than scalar Higgses (m_A ~ few hundred GeV), and third generation
scalar masses are enhanced because of new positive contributions from Higgs
loops.Comment: 16 pages and 3 figure
Discovery of a wide companion near the deuterium burning mass limit in the Upper Scorpius association
We present the discovery of a companion near the deuterium burning mass limit
located at a very wide distance, at an angular separation of 4.6+/-0.1 arcsec
(projected distance of ~ 670 AU) from UScoCTIO108, a brown dwarf of the very
young Upper Scorpius association. Optical and near-infrared photometry and
spectroscopy confirm the cool nature of both objects, with spectral types of M7
and M9.5, respectively, and that they are bona fide members of the association,
showing low gravity and features of youth. Their masses, estimated from the
comparison of their bolometric luminosities and theoretical models for the age
range of the association, are 60+/-20 and 14^{+2}_{-8} MJup, respectively. The
existence of this object around a brown dwarf at this wide orbit suggests that
the companion is unlikely to have formed in a disk based on current planet
formation models. Because this system is rather weakly bound, they did not
probably form through dynamical ejection of stellar embryos.Comment: 10 pages, including 4 figures and 2 table
Industry Supported Improved Design of DEMO BoP for HCPB BB Concept with Energy Storage System
Three-dimensional Heisenberg spin glass under a weak random anisotropy
We perform a finite-size scaling study of the three-dimensional Heisenberg spin glass in the presence of weak random anisotropic interactions, up to lattice sizes L = 32. Anisotropies have a major impact on the phase transition. The chiral-glass susceptibility does not diverge due to a large anomalous dimension. It follows that the anisotropic spin glass belongs to a Universality Class different from the isotropic model, which questions the applicability of the chirality scenario
The spin glass transition of the three dimensional Heisenberg spin glass
It is shown, by means of Monte Carlo simulation and Finite Size Scaling
analysis, that the Heisenberg spin glass undergoes a finite-temperature phase
transition in three dimensions. There is a single critical temperature, at
which both a spin glass and a chiral glass orderings develop. The Monte Carlo
algorithm, adapted from lattice gauge theory simulations, makes possible to
thermalize lattices of size L=32, larger than in any previous spin glass
simulation in three dimensions. High accuracy is reached thanks to the use of
the Marenostrum supercomputer. The large range of system sizes studied allow us
to consider scaling corrections.Comment: 4 pages, 4 Postscript figures, version to be published in Physical
Review Letter
Assessment of the efficiency of a passive safety system for prevention of severe accidents for SFR
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