1,171,667 research outputs found
Non-ergodic phases in strongly disordered random regular graphs
We combine numerical diagonalization with a semi-analytical calculations to
prove the existence of the intermediate non-ergodic but delocalized phase in
the Anderson model on disordered hierarchical lattices. We suggest a new
generalized population dynamics that is able to detect the violation of
ergodicity of the delocalized states within the Abou-Chakra, Anderson and
Thouless recursive scheme. This result is supplemented by statistics of random
wave functions extracted from exact diagonalization of the Anderson model on
ensemble of disordered Random Regular Graphs (RRG) of N sites with the
connectivity K=2. By extrapolation of the results of both approaches to
N->infinity we obtain the fractal dimensions D_{1}(W) and D_{2}(W) as well as
the population dynamic exponent D(W) with the accuracy sufficient to claim that
they are non-trivial in the broad interval of disorder strength W_{E}<W<W_{c}.
The thorough analysis of the exact diagonalization results for RRG with
N>10^{5} reveals a singularity in D_{1,2}(W)-dependencies which provides a
clear evidence for the first order transition between the two delocalized
phases on RRG at W_{E}\approx 10.0. We discuss the implications of these
results for quantum and classical non-integrable and many-body systems.Comment: 4 pages paper with 5 figures + Supplementary Material with 5 figure
Prompt Photon plus Charm Production at Next-to-Leading Order in QCD
The two particle inclusive cross section for the reaction is studied in perturbative quantum
chromodynamics at order . Differential distributions are
provided for various observables, and a comparison is made with data from the
CDF collaboration.Comment: 4 pages, LaTeX, uses stwol.sty, 6 postscript figures. Invited paper
presented by E. L. Berger at the 28th International Conference on High Energy
Physics, Warsaw, Poland, July 25 - 31, 199
Associated Production of Charm and a Hard Photon
The two particle inclusive cross section for the reaction is studied in perturbative quantum
chromodynamics at order , for large values of the transverse
momentum of the prompt photon and charm quark. Two different techniques are
used in performing the phase-space integrals; the first is purely analytical,
and the second is a combination of analytic and Monte Carlo integration
methods. The second, more versatile technique facilitates imposition of photon
isolation restrictions and other selections of relevance in experiments.
Differential distributions are provided for various observables, and a
comparison is made with preliminary data from the CDF collaboration.Comment: 6 pages. Latex file plus 4 ps files of figures submitted togther in
uuencoded form; invited talk presented by L. E. Gordon at the XXXI Rencontres
de Moriond on QCD and High Energy Hadronic Interactions, Les Arcs, France,
March, 199
Special mandrel permits uniform welding of out-of-round tubing
Clamp holds irregularly shaped pieces in lathe chuck without damage and eliminates excessive time in selecting optimum mounting. Interchangeable jaws ride in standard jaw slots but swivel so that the jaw face bears evenly against the workpiece regardless of contour. The jaws can be used on both engine and turret lathes
SU(2) and the Kauffman bracket
A direct relationship between the (non-quantum) group SU(2) and the Kauffman
bracket in the framework of Chern-Simons theory is explicitly shown.Comment: 5 page
Self-energized plasma compressor
The self-energized plasma compressor is described which compresses plasma discharged from a coaxial plasma generator. The device includes a helically shaped coil which is coaxially aligned with the center axis of the coaxial plasma generator. The plasma generator creates a current through the helical coil which, in turn, generates a time varying magnetic field that creates a force which acts radially upon the plasma. The coaxial plasma generator and helical coil move the plasma under high pressure and temperature to the narrow end of the coil. Positioned adjacent to the narrow end of the coil are beads which are engaged by the plasma to be accelerated to hypervelocities for simulating meteoroids
Instrument quickly transposes ground reference target to eye level
Optical alignment of equipment is facilitated by a traverse target with a string suspending a plumb bob to transpose the ground level point to eye level operation. This instrument appreciably decreases the time required from the present method but achieves the same degree of precision
Differential identities for parametric correlation functions in disordered systems
Copyright © 2008 The American Physical Society.We derive a family of differential identities for parametric correlation functions in disordered systems by casting them as first- or second-order Ward identities of an associated matrix model. We show that this approach allows for a systematic classification of such identities, and provides a template for deriving higher-order results. We also reestablish and generalize some identities of this type which had been derived previously using a different method
Superradiance and multiple scattering of photons in atomic gases
We study the influence of cooperative effects such as superradiance and
subradiance, on the scattering properties of dilute atomic gases. We show that
cooperative effects lead to an effective potential between pairs of atoms that
decays like . In the case of superradiance, this potential is attractive
for close enough atoms and can be interpreted as a coherent mesoscopic effect.
We consider a model of multiple scattering of a photon among superradiant pairs
and calculate the elastic mean free path and the group velocity. We study first
the case of a scalar wave which allows to obtain and to understand basic
features of cooperative effects and multiple scattering. We then turn to the
general problem of a vector wave. In both cases, we obtain qualitatively
similar results and derive, for the case of a scalar wave, analytic expressions
of the elastic mean free path and of the group velocity for an arbitrary (near
resonance) detuning.Comment: 12 pages, 7 figure
- …