1,274 research outputs found
Classical and Non-Relativistic Limits of a Lorentz-Invariant Bohmian Model for a System of Spinless Particles
A completely Lorentz-invariant Bohmian model has been proposed recently for
the case of a system of non-interacting spinless particles, obeying
Klein-Gordon equations. It is based on a multi-temporal formalism and on the
idea of treating the squared norm of the wave function as a space-time
probability density. The particle's configurations evolve in space-time in
terms of a parameter {\sigma}, with dimensions of time. In this work this model
is further analyzed and extended to the case of an interaction with an external
electromagnetic field. The physical meaning of {\sigma} is explored. Two
special situations are studied in depth: (1) the classical limit, where the
Einsteinian Mechanics of Special Relativity is recovered and the parameter
{\sigma} is shown to tend to the particle's proper time; and (2) the
non-relativistic limit, where it is obtained a model very similar to the usual
non-relativistic Bohmian Mechanics but with the time of the frame of reference
replaced by {\sigma} as the dynamical temporal parameter
Ground state charmed meson spectra for N_f=2+1+1
We present a preliminary study of the charmed meson spectra using the
electrically neutral subset of the new Budapest-Marseille-Wuppertal N_f=2+1+1
gauge configurations that utilise the 3-HEX smeared clover action. The analysis
is performed with a focus on the hyperfine splitting.Comment: 7 pages, 5 figures; presentation given at the 33rd International
Symposium on Lattice Field Theory (Lattice 2015), 14 - 18 July 2015, Kobe,
Japa
Lattice QCD with mixed actions
We discuss some of the implications of simulating QCD when the action used
for the sea quarks is different from that used for the valence quarks. We
present exploratory results for the hadron mass spectrum and pseudoscalar meson
decay constants using improved staggered sea quarks and HYP-smeared overlap
valence quarks. We propose a method for matching the valence quark mass to the
sea quark mass and demonstrate it on UKQCD clover data in the simpler case
where the sea and valence actions are the same.Comment: 15 pages, 10 figures some minor modification to text and figures.
Accepted for publicatio
QCD thermodynamics with dynamical overlap fermions
We study QCD thermodynamics using two flavors of dynamical overlap fermions
with quark masses corresponding to a pion mass of 350 MeV. We determine several
observables on N_t=6 and 8 lattices. All our runs are performed with fixed
global topology. Our results are compared with staggered ones and a nice
agreement is found.Comment: 14 pages, 6 figures, 1 tabl
Microscopic chaos from Brownian motion?
A recent experiment on Brownian motion has been interpreted to exhibit direct
evidence for microscopic chaos. In this note we demonstrate that virtually
identical results can be obtained numerically using a manifestly
microscopically nonchaotic system.Comment: 3 pages, 1 figure, Comment on P. Gaspard et al, Nature vol 394, 865
(1998); rewritten in a more popular styl
X-Ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu
We have used a MHz lock-in x-ray spectro-microscopy technique to directly
detect changes of magnetic moments in Cu due to spin injection from an adjacent
Co layer. The elemental and chemical specificity of x-rays allows us to
distinguish two spin current induced effects. We detect the creation of
transient magnetic moments of on Cu atoms
within the bulk of the 28 nm thick Cu film due to spin-accumulation. The moment
value is compared to predictions by Mott's two current model. We also observe
that the hybridization induced existing magnetic moments on Cu interface atoms
are transiently increased by about 10% or .
This reveals the dominance of spin-torque alignment over Joule heat induced
disorder of the interfacial Cu moments during current flow
The density matrix in the de Broglie-Bohm approach
If the density matrix is treated as an objective description of individual
systems, it may become possible to attribute the same objective significance to
statistical mechanical properties, such as entropy or temperature, as to
properties such as mass or energy. It is shown that the de Broglie-Bohm
interpretation of quantum theory can be consistently applied to density
matrices as a description of individual systems. The resultant trajectories are
examined for the case of the delayed choice interferometer, for which Bell
appears to suggest that such an interpretation is not possible. Bell's argument
is shown to be based upon a different understanding of the density matrix to
that proposed here.Comment: 15 pages, 4 figure
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