1,216,650 research outputs found
Covariant description of kinetic freeze out through a finite space-like layer
The problem of Freeze Out (FO) in relativistic heavy ion reactions is
addressed. We develop and analyze an idealized one-dimensional model of FO in a
finite layer, based on the covariant FO probability. The resulting post FO
phase-space distributions are discussed for different FO probabilities and
layer thicknesses.Comment: 16 pages, 19 figures, changed content, references adde
Localization and critical diffusion of quantum dipoles in two dimensions
We discuss quantum propagation of dipole excitations in two dimensions. This
problem differs from the conventional Anderson localization due to existence of
long range hops. We found that the critical wavefunctions of the dipoles always
exist which manifest themselves by a scale independent diffusion constant. If
the system is T-invariant the states are critical for all values of the
parameters. Otherwise, there can be a "metal-insulator" transition between this
"ordinary" diffusion and the Levy-flights (the diffusion constant
logarithmically increasing with the scale). These results follow from the
two-loop analysis of the modified non-linear supermatrix -model.Comment: 4.2 page
Finite Temperature Casimir Effect in the Presence of Extra Dimensions
We consider the finite temperature Casimir force acting on two parallel
plates in a closed cylinder with the same cross section of arbitrary shape in
the presence of extra dimensions. Dirichlet boundary conditions are imposed on
one plate and fractional Neumann conditions with order between zero (Dirichlet)
and one (Neumann) are imposed on the other plate. Formulas for the Casimir
force show that it is always attractive for Dirichlet boundary conditions, and
is always repulsive when the fractional order is larger than 1/2. For some
fractional orders less than 1/2, the Casimir force can be either attractive or
repulsive depending on the size of the internal manifold and temperature.Comment: To appear in the proceedings of 9th Conference on Quantum Field
Theory under the Influence of External Conditions (QFEXT 09): Devoted to the
Centenary of H. B. G. Casimir, Norman, Oklahoma, 21-25 Sep 200
Device for tensioning test specimens within an hermetically sealed chamber
The device is characterized by a support column adapted to be received within an insulated, hermetically sealable chamber. A plurality of anchor pins are mounted on the column for releasibly connecting thereto a plurality of test specimens. A plurality of axially displaceable pull rods are received by the column in coaxial alignment with the anchor pins. One end of each pull rod is provided with a coupling for connecting the pull rod to a test specimen. The opposite end of the pull rod is entended through a cover plate and adapted to be connected with a remotely related linear actuator through a connecting link including a load cell for measuring stress as the pull rod is placed in tension by the actuator
- …