Energy Spectrum and Determinant Method in Quantized Field Theory

The atom-field interaction is formulated within the fully quantized-field theory, starting from a detailed analysis of the transformation from the fundamental minimal coupling interaction Hamiltonian to the electric dipole Hamiltonian used extensively in quantum optics. Spontaneous emission, radiative level shifts, and the natural radiative lineshape are treated in both the Schrodinger and Heisenberg pictures, with emphasis on the roles of vacuum field fluctuations, radiation reaction, and the fluctuation-dissipation relation between them. The shortcomings of semiclassical radiation theories are discussed.

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Random boundary geometry and gravity dual of $$ T\overline{T} $$ deformation

Journal of High Energy Physics ◽

10.1007/jhep11(2020)108 ◽

2020 ◽

Vol 2020 (11) ◽

Cited By ~ 1

Author(s):

Shinji Hirano ◽

Masaki Shigemori

Keyword(s):

Field Theory ◽

Free Energy ◽

Energy Spectrum ◽

Correlation Functions ◽

Degrees Of Freedom ◽

Dual Language ◽

Renormalization Group Flow ◽

Conformal Field ◽

Logarithmic Corrections ◽

Group Flow

Abstract We study the random geometry approach to the $$ T\overline{T} $$ T T ¯ deformation of 2d conformal field theory developed by Cardy and discuss its realization in a gravity dual. In this representation, the gravity dual of the $$ T\overline{T} $$ T T ¯ deformation becomes a straightforward translation of the field theory language. Namely, the dual geometry is an ensemble of AdS3 spaces or BTZ black holes, without a finite cutoff, but instead with randomly fluctuating boundary diffeomorphisms. This reflects an increase in degrees of freedom in the renormalization group flow to the UV by the irrelevant $$ T\overline{T} $$ T T ¯ operator. We streamline the method of computation and calculate the energy spectrum and the thermal free energy in a manner that can be directly translated into the gravity dual language. We further generalize this approach to correlation functions and reproduce the all-order result with universal logarithmic corrections computed by Cardy in a different method. In contrast to earlier proposals, this version of the gravity dual of the $$ T\overline{T} $$ T T ¯ deformation works not only for the energy spectrum and the thermal free energy but also for correlation functions.

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N-quantum approach to the BCS theory of superconductivity

Canadian Journal of Physics ◽

10.1139/p94-073 ◽

1994 ◽

Vol 72 (9-10) ◽

pp. 574-577 ◽

Cited By ~ 1

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.

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The Non-Metric Solution to Graviton as Goldstone Boson

10.20944/preprints202010.0315.v1 ◽

2020 ◽

Author(s):

Aayush Verma

Keyword(s):

Field Theory ◽

Goldstone Boson ◽

Vacuum State ◽

Metric Tensor ◽

Goldstone Bosons ◽

Recent Advancement ◽

Quantized Field ◽

The 1960S ◽

Extended Theories ◽

Theories Of Gravitation

The study of Graviton as Goldstone bosons appeared in the 1960s, after Bjorken interacting idea of Electrodynamics. However, no recent advancement has been done in the field, because of very constraints as well as low-attractiveness of the theory. We do the non-metric tensor (covariant derivative of the metric tensor) case of Gravitation and eventually get SO(1,3) broken in the vacuum state of quantized field theory, then find the Graviton as Goldstone Boson. We, in final, see that Gravitons can have appearances in many modified (and extended) theories of Gravitation.

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