14,210 research outputs found
Some Applications of Thermal Field Theory to Quark-Gluon Plasma
The lecture provides a brief introduction of thermal field theory within
imaginary time formalism, the Hard Thermal Loop perturbation theory and some of
its application to the physics of the quark-gluon plasma, possibly created in
relativistic heavy ion collisions.Comment: 17 pages, 12 figures : Lectures given in "Workshop on Hadron Physics"
during March 7-17, 2005, Puri, Indi
Mean parameter model for the Pekar-Fr\"{o}hlich polaron in a multilayered heterostructure
The polaron energy and the effective mass are calculated for an electron
confined in a finite quantum well constructed of
layers. To simplify the study we suggest a model in which parameters of a
medium are averaged over the ground-state wave function. The rectangular and
the Rosen-Morse potential are used as examples.
To describe the confined electron properties explicitly to the second order
of perturbations in powers of the electron-phonon coupling constant we use the
exact energy-dependent Green function for the Rosen-Morse confining potential.
In the case of the rectangular potential, the sum over all intermediate virtual
states is calculated. The comparison is made with the often used leading term
approximation when only the ground-state is taken into account as a virtual
state. It is shown that the results are quite different, so the incorporation
of all virtual states and especially those of the continuous spectrum is
essential.
Our model reproduces the correct three-dimensional asymptotics at both small
and large widths. We obtained a rather monotonous behavior of the polaron
energy as a function of the confining potential width and found a peak of the
effective mass. The comparison is made with theoretical results by other
authors. We found that our model gives practically the same (or very close)
results as the explicit calculations for potential widths .Comment: 12 pages, LaTeX, including 5 PS-figures, subm. to Phys. Rev. B, new
data are discusse
Modes of Foreign Entry under Asymmetric Information about Potential Technology Spillovers
This paper studies the effect of technology spillovers on the entry decision of a multinational enterprise into a foreign market. Two alternative entry modes for a foreign direct investment are considered: Greenfield investment versus acquisition. We find that with quantity competition a spillover makes acquisitions less attractive, while with price competition acquisitions become more attractive. Asymmetric information about potential spillovers always reduces the number of
acquisitions independently of whether the host country or the entrant has private information. Interestingly, we find that asymmetric information always hurts the entrant, while it sometimes is in favor of the host country
Nearest pattern interaction and global pattern formation
We studied the effect of nearest pattern interaction on a globally pattern
formation in a 2-dimensional space, where patterns are to grow initially from a
noise in the presence of periodic supply of energy. Although our approach is
general, we found that this study is relevant in particular to the pattern
formation on a periodically vibrated granular layer, as it gives a unified
perspective of the experimentally observed pattern dynamics such as oscillon
and stripe formations, skew-varicose and crossroll instabilities, and also a
kink formation and decoration
Dirac Neutrinos, Dark Energy and Baryon Asymmetry
We explore a new origin of neutrino dark energy and baryon asymmetry in the
universe. The neutrinos acquire small masses through the Dirac seesaw
mechanism. The pseudo-Nambu-Goldstone boson associated with neutrino
mass-generation provides a candidate for dark energy. The puzzle of
cosmological baryon asymmetry is resolved via neutrinogenesis.Comment: 6 pages, 1 figure. Accepted by JCAP (only minor rewordings, refs
added
Deformation Theory of Holomorphic Vector Bundles, Extended Conformal Symmetry and Extensions of 2D Gravity
Developing on the ideas of R. Stora and coworkers, a formulation of two
dimensional field theory endowed with extended conformal symmetry is given,
which is based on deformation theory of holomorphic and Hermitian spaces. The
geometric background consists of a vector bundle over a closed surface
endowed with a holomorphic structure and a Hermitian structure
subordinated to it. The symmetry group is the semidirect product of the
automorphism group of and the extended Weyl group of and acts on the holomorphic and Hermitian structures. The
extended Weyl anomaly can be shifted into an automorphism chirally split
anomaly by adding to the action a local counterterm, as in ordinary conformal
field theory. The dependence on the scale of the metric on the fiber of is
encoded in the Donaldson action, a vector bundle generalization of the
Liouville action. The Weyl and automorphism anomaly split into two
contributions corresponding respectively to the determinant and
projectivization of . The determinant part induces an effective ordinary
Weyl or diffeomorphism anomaly and the induced central charge can be computed.Comment: 49 pages, plain TeX. A number of misprints have been correcte
Quasiperiodic waves at the onset of zero Prandtl number convection with rotation
We show the possibility of quasiperiodic waves at the onset of thermal
convection in a thin horizontal layer of slowly rotating zero-Prandtl number
Boussinesq fluid confined between stress-free conducting boundaries. Two
independent frequencies emerge due to an interaction between a stationary
instability and a self-tuned wavy instability in presence of coriolis force, if
Taylor number is raised above a critical value. Constructing a dynamical system
for the hydrodynamical problem, the competition between the interacting
instabilities is analyzed. The forward bifurcation from the conductive state is
self-tuned.Comment: 9 pages of text (LaTex), 5 figures (Jpeg format
Symmetry Breaking in Few Layer Graphene Films
Recently, it was demonstrated that the quasiparticle dynamics, the
layer-dependent charge and potential, and the c-axis screening coefficient
could be extracted from measurements of the spectral function of few layer
graphene films grown epitaxially on SiC using angle-resolved photoemission
spectroscopy (ARPES). In this article we review these findings, and present
detailed methodology for extracting such parameters from ARPES. We also present
detailed arguments against the possibility of an energy gap at the Dirac
crossing ED.Comment: 23 pages, 13 figures, Conference Proceedings of DPG Meeting Mar 2007
Regensburg Submitted to New Journal of Physic
Non-isothermal model for the direct isotropic/smectic-A liquid crystalline transition
An extension to a high-order model for the direct isotropic/smectic-A liquid
crystalline phase transition was derived to take into account thermal effects
including anisotropic thermal diffusion and latent heat of phase-ordering.
Multi-scale multi-transport simulations of the non-isothermal model were
compared to isothermal simulation, showing that the presented model extension
corrects the standard Landau-de Gennes prediction from constant growth to
diffusion-limited growth, under shallow quench/undercooling conditions.
Non-isothermal simulations, where meta-stable nematic pre-ordering precedes
smectic-A growth, were also conducted and novel non-monotonic
phase-transformation kinetics observed.Comment: First revision: 20 pages, 7 figure
- …