N-quantum approach to the BCS theory of superconductivity

1994 ◽  
Vol 72 (9-10) ◽  
pp. 574-577 ◽  
Author(s):  
O. W. Greenberg
Keyword(s):  
Field Theory ◽  
Finite Temperature ◽  
Bcs Theory ◽  
Zero Temperature ◽  
General Applicability ◽  
Finite Temperature Field Theory ◽  
Gap Equation ◽  
Quantum Approach ◽  
Quantized Field ◽  
Theory Of Superconductivity

A method of general applicability to the solution of second-quantized field theories at finite temperature is illustrated using the BCS (Bardeen–Cooper–Schrieffer) model of superconductivity. Finite-temperature field theory is treated using the thermo field-theory formalism of Umezawa and collaborators. The solution of the field theory uses an expansion in thermal modes analogous to the Haag expansion in asymptotic fields used in the N-quantum approximation at zero temperature. The lowest approximation gives the usual gap equation.

scholarly journals Cutting Rules at Finite Temperature

1997 ◽  
Vol 12 (33) ◽  
pp. 2481-2496 ◽  
Author(s):  
Paulo F. Bedaque ◽  
Ashok Das ◽  
Satchidananda Naik
Keyword(s):  
Field Theory ◽  
Temperature Field ◽  
Real Time ◽  
Imaginary Part ◽  
Physical Interpretation ◽  
Finite Temperature ◽  
Zero Temperature ◽  
Finite Temperature Field Theory ◽  
The Real

We discuss the cutting rules in the real-time approach to finite temperature field theory and show the existence of cancellations among classes of cut graphs which allows a physical interpretation of the imaginary part of the relevant amplitude in terms of the underlying microscopic processes. Furthermore, with these cancellations, any calculation of the imaginary part of an amplitude becomes much easier and completely parallel to the zero temperature case.

THE SCHWINGER α-PARAMETRIC REPRESENTATION OF THE FINITE-TEMPERATURE FIELD THEORY: RENORMALIZATION II

1992 ◽  
Vol 07 (01) ◽  
pp. 193-200
Author(s):  
MABROUK BENHAMOU ◽  
AHMED KASSOU-OU-ALI
Keyword(s):  
Field Theory ◽  
Temperature Field ◽  
Theta Function ◽  
Finite Temperature ◽  
Parametric Representation ◽  
Field Theories ◽  
Zero Temperature ◽  
Scalar Theory ◽  
Charged Scalar ◽  
Finite Temperature Field Theory

We extend to finite-temperature field theories, involving charged scalar or nonvanishing spin particles, the α parametrization of field theories at zero temperature. This completes a previous work concerning the scalar theory. As there, a function θ, which contains all temperature dependence, appears in the α integrand. The function θ is an extension of the usual theta function. The implications of the α parametrization for the renormalization problem are discussed.

CONDENSATION ENERGY OF THE NAMBU-JONA-LASINIO VACUUM AND THE MIT BAG CONSTANT

1991 ◽  
Vol 06 (03) ◽  
pp. 501-515 ◽  
Author(s):  
SHUXI LI ◽  
R.S. BHALERAO ◽  
R.K. BHADURI
Keyword(s):  
Field Theory ◽  
Temperature Field ◽  
Finite Temperature ◽  
Condensation Energy ◽  
Finite Temperature Field Theory ◽  
Gap Equation ◽  
The Difference ◽  
Two Phases ◽  
Goldstone Modes ◽  
Bag Constant

The energy densities of the vacuum in the Wigner and the Goldstone modes of the Nambu-Jona-Lasinio Hamiltonian are calculated. The difference of these two quantities is analogous to the condensation energy of a BCS superconductor, and is used here to estimate the temperature dependence of the MIT bag constant. The formalism of da Providencia et al. is generalized to finite temperatures, yielding the same gap equation as the finite-temperature field theory. The thermodynamics of the vacuum in the two phases is studied.

Review of the holographic Lifshitz theory

2014 ◽  
Vol 29 (24) ◽  
pp. 1430049 ◽  
Author(s):  
Chanyong Park
Keyword(s):  
Field Theory ◽  
Finite Temperature ◽  
Quasinormal Mode ◽  
Thermodynamic Quantities ◽  
Black Brane ◽  
Zero Temperature ◽  
Hydrodynamic Properties ◽  
Relativistic Field ◽  
Thermal Entropy ◽  
Lifshitz Theory

We review interesting results achieved in recent studies on the holographic Lifshitz field theory. The holographic Lifshitz field theory at finite temperature is described by a Lifshitz black brane geometry. The holographic renormalization together with the regularity of the background metric allows to reproduce thermodynamic quantities of the dual Lifshitz field theory where the Bekenstein–Hawking entropy appears as the renormalized thermal entropy. All results satisfy the desired black brane thermodynamics. In addition, hydrodynamic properties are further reviewed in which the holographic retarded Green functions of the current and momentum operators are studied. In a nonrelativistic Lifshitz field theory, intriguingly, there exists a massive quasinormal mode at finite temperature whose effective mass is linearly proportional to temperature. Even at zero temperature and in the nonzero momentum limit, a quasinormal mode still remains unlike the dual relativistic field theory. Finally, we account for how adding impurity modifies the electric property of the nonrelativistic Lifshitz theory.

Finite-temperature field theory with a cutoff

1993 ◽  
Vol 47 (3) ◽  
pp. 1219-1224 ◽  
Author(s):  
P. Amte ◽  
C. Rosenzweig
Keyword(s):  
Field Theory ◽  
Temperature Field ◽  
Finite Temperature ◽  
Finite Temperature Field Theory

Reorganizing Finite Temperature Field Theory: Part I.: Scalar Field Theory

2001 ◽  
Vol 16 (supp01c) ◽  
pp. 1277-1280 ◽  
Author(s):  
Michael Strickland
Keyword(s):  
Field Theory ◽  
Perturbation Theory ◽  
Temperature Field ◽  
Finite Temperature ◽  
Weak Coupling ◽  
Weak Coupling Limit ◽  
Finite Temperature Field Theory ◽  
Expansion Point ◽  
Perturbative Limit ◽  
Standard Perturbation Theory

I present a method for self-consistently including the effects of screening in finite-temperature field theory calculations. The method reproduces the perturbative limit in the weak-coupling limit and for intermediate couplings this method has much better convergence than standard perturbation theory. The method relies on a reorganization of perturbation theory accomplished by shifting the expansion point used to calculate quantum loop corrections. I will present results from a three-loop calculation within this formalism for scalar λϕ4.

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