scholarly journals Infrared behavior of the dispersion relations in high-temperature scalar QED

2006 ◽  
Vol 2006 (01) ◽  
pp. 161-161 ◽  
Author(s):  
Abdessamad Abada ◽  
Karima Bouakaz
Keyword(s):  
High Temperature ◽  
Dispersion Relations ◽  
Infrared Behavior ◽  
Temperature Scalar

scholarly journals Optical Dispersion Relations for “Diamondlike” Carbon Films

1989 ◽  
Vol 152 ◽  
Author(s):  
Samuel A. Alterovitz ◽  
Robert M. Sieg ◽  
Neil S. Shoemaker ◽  
John J. Pouch
Keyword(s):  
High Temperature ◽  
Amorphous Carbon ◽  
Energy Gap ◽  
Carbon Films ◽  
Dispersion Relations ◽  
Index Of Refraction ◽  
Least Squares Fit ◽  
Diamondlike Carbon ◽  
Good Agreement ◽  
Complex Index Of Refraction

ABSTRACTEllipsometric measurements on plasma deposited “diamondlike” amorphous carbon (a-C:H) films were taken in the visible, (E = 1.75 to 3.5 eV). The films were deposited on Si and their properties were varied using high temperature (up to 750 °C) anneals. The real (n) and imaginary (k) parts of the complex index of refraction N were obtained simultaneously. Following the theory of Forouhi and Bloomer (Phys. Rev. B34, 7018 (1986)), a least squares fit was used to find the dispersion relations n(E) and k(E). Reasonably good fits were obtained, showing that the theory can be used for a-C:H films. Morever, the value of the energy gap Eg obtained in this way was compared to the Eg value using conventional Tauc plots and reasonably good agreement was obtained.

scholarly journals GLUONS AT FINITE TEMPERATURE IN LANDAU GAUGE YANG–MILLS THEORY

2005 ◽  
Vol 20 (24) ◽  
pp. 1797-1811 ◽  
Author(s):  
AXEL MAAS
Keyword(s):  
High Temperature ◽  
Finite Temperature ◽  
Landau Gauge ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Soft Scale ◽  
Yang Mills ◽  
Infrared Behavior ◽  
The One

The infrared behavior of Yang–Mills theory at finite temperature provides access to the role of confinement. In this review recent results on this topic from lattice calculations and especially Dyson–Schwinger studies are discussed. These indicate persistence of a residual confinement even in the high-temperature phase. The confinement mechanism is very similar to the one in the vacuum for the chromomagnetic sector. In the chromoelectric sector screening occurs at the soft scale g2T, although not leading to a perturbative behavior.

BLOCH–NORDSIECK ESTIMATES OF A HIGH-TEMPERATURE SCALAR FIELD THEORY

2005 ◽  
Vol 20 (32) ◽  
pp. 7525-7546 ◽  
Author(s):  
B. CANDELPERGHER ◽  
H. M. FRIED ◽  
T. GRANDOU
Keyword(s):  
Field Theory ◽  
High Temperature ◽  
Scalar Field ◽  
Heat Bath ◽  
Damping Factor ◽  
Scalar Field Theory ◽  
Clear Cut ◽  
Subsequent Application ◽  
Thermal Medium ◽  
Temperature Scalar

In anticipation of subsequent application to QED and QCD, we consider the case of a model, high temperature, relativistic, scalar field theory. We introduce into the exact, nonperturbative, functional expressions of this "quenched" model, a new Fradkin representation, and extract the infrared/Bloch–Nordsieck/(IR/BN) contributions of every perturbative graph, in order to circumvent the lack of a clear-cut separation of energy scales of previous semiperturbative treatments. Our results are applicable to the absorption of a fast particle which enters a heat bath, as well as to the propagation of a symmetric pulse within the thermal medium due to the appearance of an instantaneous, shockwave-like source acting in the medium. In momentum space, the former case displays a propagator which decays exponentially with increasing time, in addition to a new damping factor independent of time. The latter case displays an exponential growth with time of the symmetric pulse, generating effective and increasing plasmon waves, in competition with damping independent of time. When extended to QCD, qualitative applications could be made to RHIC scattering, in which a fireball appears, expands and is damped away.

Far infrared behavior of thin film high temperature superconductors

1977 ◽  
Vol 41 (3) ◽  
pp. L61-L64 ◽  
Author(s):  
S.W. McKnight ◽  
R.H. Thorland ◽  
S. Perkowitz
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
High Temperature Superconductors ◽  
Far Infrared ◽  
Infrared Behavior

scholarly journals SCREENING LENGTH, DISPERSION RELATIONS AND QUARK POTENTIAL IN THERMO FIELD DYNAMICS

2002 ◽  
Vol 17 (21) ◽  
pp. 2911-2923
Author(s):  
WANYUN ZHAO ◽  
F. C. KHANNA
Keyword(s):  
High Temperature ◽  
Quark Gluon Plasma ◽  
Gluon Plasma ◽  
Dispersion Relations ◽  
Ladder Approximation ◽  
Screening Length ◽  
The Real ◽  
Self Energy ◽  
Thermo Field Dynamics ◽  
Quark Potential

The screening length in a quark–gluon plasma, the dispersion relations of thermal gluon self-energy and the quark potential at high temperature are studied within the thermo field dynamics framework. By calculating the real and imaginary parts, of the gluon self-energy in one-loop order in thermo field dynamics, we obtain an expression for the screening length in a quark–gluon plasma and the dispersion relation between the real and imaginary parts. At high temperature, using photon exchange between electron-positron in a skeleton expansion and ladder approximation, the screened Coulomb potential and an expression for the screened quark potential is obtained.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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