scholarly journals Back reaction, covariant anomaly and effective action

2010 ◽  
Vol 2010 (5) ◽  
Author(s):  
Qing-Quan Jiang ◽  
Xu Cai
Keyword(s):  
Effective Action ◽  
Back Reaction ◽  
Covariant Anomaly

scholarly journals Trace Anomaly and Nonlocal Effective Action for 2-D Conformally Invariant Scalar Interacting with Dilaton

1997 ◽  
Vol 12 (28) ◽  
pp. 2083-2087 ◽  
Author(s):  
Shin'ichi Nojiri ◽  
Sergei D. Odintsov
Keyword(s):  
Black Holes ◽  
Effective Action ◽  
Conformal Anomaly ◽  
Back Reaction ◽  
Conformally Invariant ◽  
Trace Anomaly ◽  
Invariant Scalar ◽  
The One

Using the results of the calculation of the one-loop effective action (E. Elizalde et al., Phys. Rev.D49, 2852 (1994)), we find the trace anomaly for most general conformally invariant 2-D dilaton coupled scalar–dilaton system (the contribution of dilaton itself is included). The nonlocal effective action induced by conformal anomaly for such system is found. That opens new possibilities in generalizing of CGHS-like model for the study of back-reaction of matter to 2-D black holes.

scholarly journals Quantum Scalar Field in the FRW Universe with a Constant Electromagnetic Background

1997 ◽  
Vol 12 (27) ◽  
pp. 4837-4867 ◽  
Author(s):  
S. P. Gavrilov ◽  
D. M. Gitman ◽  
S. D. Odintsov
Keyword(s):  
Electromagnetic Field ◽  
Scalar Field ◽  
Effective Action ◽  
Proper Time ◽  
Back Reaction ◽  
De Sitter ◽  
Frw Universe ◽  
Massive Scalar Field ◽  
Mean Values ◽  
Constant Electromagnetic Field

We discuss a massive scalar field with conformal coupling in the Friedmann–Robertson–Walker (FRW) Universe of a special type with a constant electromagnetic field. Treating an external gravitational–electromagnetic background exactly, at the first time the proper-time representations for out–in, in–in and out–out scalar Green functions are explicitly constructed as proper-time integrals over the corresponding (complex) contours. The vacuum-to-vacuum transition amplitudes and the number of created particles are found and vacuum instability is discussed. The mean values of the current and the energy–momentum tensor are evaluated, and different approximations for them are investigated. The back reaction of the particles created to the electromagnetic field is estimated in different regimes. The connection between the proper-time method and the effective action is outlined. The effective action in scalar QED in the weakly curved FRW Universe (de Sitter space) with a weak constant electromagnetic field is found as a derivative expansion over curvature and electromagnetic field strength. Possible further applications of the results are mentioned.

scholarly journals A new way of calculating the effective potential for a light radion

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
J.M. Lizana ◽  
M. Olechowski ◽  
S. Pokorski
Keyword(s):  
Critical Temperature ◽  
Effective Potential ◽  
Effective Action ◽  
Equations Of Motion ◽  
Field Method ◽  
The Other ◽  
Back Reaction ◽  
Stabilization Mechanism ◽  
Numerical Examples ◽  
Effective Potentials

Abstract We address again the old problem of calculating the radion effective potential in Randall-Sundrum scenarios, with the Goldberger-Wise stabilization mechanism. Various prescriptions have been used in the literature, most of them based on heuristic derivations and then applied in some approximations. We define rigorously a light radion 4D effective action by using the interpolating field method. For a given choice of the interpolating field, defined as a functional of 5D fields, the radion effective action is uniquely defined by the procedure of integrating out the other fields, with the constrained 5D equations of motion always satisfied with help of the Lagrange multipliers. Thus, for a given choice of the interpolating fields we obtain a precise prescription for calculating the effective potential. Different choices of the interpolating fields give different prescriptions but in most cases very similar effective potentials. We confirm the correctness of one prescription used so far on a more heuristic basis and also find several new, much more economical, ways of calculating the radion effective potential. Our general considerations are illustrated by several numerical examples. It is shown that in some cases the old methods, especially in models with strong back-reaction, give results which are off even by orders of magnitude. Thus, our results are important e.g. for estimation of critical temperature in phase transitions.

scholarly journals STOCHASTIC GROSS-PITAEVSKY EQUATION FOR BEC VIA COARSE-GRAINED EFFECTIVE ACTION

2007 ◽  
Vol 21 (23n24) ◽  
pp. 4239-4247 ◽  
Author(s):  
ESTEBAN CALZETTA ◽  
B. L. HU ◽  
ENRIC VERDAGUER
Keyword(s):  
Effective Action ◽  
Functional Method ◽  
Einstein Condensate ◽  
Functional Integral ◽  
Coarse Grained ◽  
Nonequilibrium Dynamics ◽  
Langevin Equations ◽  
Short Paper ◽  
Original Research ◽  
Back Reaction

We sketch the major steps in a functional integral derivation of a new set of stochastic Gross-Pitaevsky equations (GPE) for a Bose-Einstein condensate (BEC) confined to a trap at zero temperature with the averaged effects of non-condensate modes incorporated as stochastic sources. The closed-time-path (CTP) coarse-grained effective action (CGEA) or the equivalent influence functional method is particularly suitable because it can account for the full back-reaction of the noncondensate modes on the condensate dynamics self-consistently. The Langevin equations derived here containing nonlocal dissipation together with colored and multiplicative noises are useful for a stochastic (as distinguished from a kinetic) description of the nonequilibrium dynamics of a BEC. This short paper contains original research results not yet published anywhere.

scholarly journals QUANTUM GRAVITY WITHOUT GHOSTS

1998 ◽  
Vol 13 (30) ◽  
pp. 2475-2479 ◽  
Author(s):  
BRYCE DEWITT ◽  
C. MOLINA-PARÍS
Keyword(s):  
Black Holes ◽  
Effective Action ◽  
Fiber Bundle ◽  
Radiative Decay ◽  
Initial Conditions ◽  
Back Reaction ◽  
Expectation Values ◽  
Dynamical Equations ◽  
Gauge Fixing ◽  
Bundle Structure

We give an outline of a recently discovered technique for building quantum effective action that is completely independent of gauge-fixing choices and ghost determinants. One makes maximum use of the geometry and fiber bundle structure of the space of field histories and introduces a set of nonlocal composite fields: the geodesic normal fields based on Vilkovisky's connection on the space of histories. The closed-time-path formalism of Schwinger, Bakshi, Mahantappa et al. can be adapted for these fields, and a set of gauge-fixing-independent dynamical equations for their expectation values (starting from given initial conditions) can be computed. An obvious application for such equations is to the study of the formation and radiative decay of black holes, and to other back-reaction problems.

Effective action on global warming?

1990 ◽  
Vol 4 (6) ◽  
pp. 262
Author(s):  
P.R. Wyman
Keyword(s):  
Global Warming ◽  
Effective Action

scholarly journals More on complex Sachdev-Ye-Kitaev eternal wormholes

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Pengfei Zhang
Keyword(s):  
Black Hole ◽  
Ground State ◽  
Effective Action ◽  
Chemical Potential ◽  
Specific Charge ◽  
Zero Temperature ◽  
Small Coupling ◽  
Chemical Potentials ◽  
Quench Dynamics ◽  
Two Sides

Abstract In this work, we study a generalization of the coupled Sachdev-Ye-Kitaev (SYK) model with U(1) charge conservations. The model contains two copies of the complex SYK model at different chemical potentials, coupled by a direct hopping term. In the zero-temperature and small coupling limit with small averaged chemical potential, the ground state is an eternal wormhole connecting two sides, with a specific charge Q = 0, which is equivalent to a thermofield double state. We derive the conformal Green’s functions and determine corresponding IR parameters. At higher chemical potential, the system transit into the black hole phase. We further derive the Schwarzian effective action and study its quench dynamics. Finally, we compare numerical results with the analytical predictions.

Sign in / Sign up

Export Citation Format

Share Document