scholarly journals Accelerated paths and Unruh effect. Part I. Scalars and fermions in Anti De Sitter spacetime

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Shahnewaz Ahmed ◽  
Mir Mehedi Faruk
Keyword(s):  
Scalar Field ◽  
Response Function ◽  
Matter Field ◽  
Detector Response ◽  
Dirac Field ◽  
Massless Scalar ◽  
Unruh Effect ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Ads Spacetime

Abstract We have investigated the Unruh effect in Anti de-Sitter (AdS) spacetime by examining the response function of an Unruh-DeWitt particle detector with uniform constant acceleration. An exact expression of the detector response function for the scalar field has been obtained with different levels of non-linearity in even dimensional AdS spacetime. We also showed how the response of the accelerated Unruh detector coupled quadratically to massless Dirac field in D dimensional (D ≥ 2) AdS spacetime is proportional to that of a detector linearly coupled to a massless scalar field in 2D dimensional AdS spacetime. Here, the fermionic and scalar matter field is coupled minimally and conformally to the background AdS metric, respectively. Finally, we discuss about the extension of the results for more general stationary motion.

scholarly journals Unruh-DeWitt detector responses for complex scalar fields in de Sitter spacetime

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Md Sabir Ali ◽  
Sourav Bhattacharya ◽  
Kinjalk Lochan
Keyword(s):  
Scalar Field ◽  
Response Function ◽  
Scalar Fields ◽  
Detector Response ◽  
Massless Scalar Field ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Complex Scalar ◽  
Sitter Spacetime ◽  
Complex Scalar Field

Abstract We derive the response function for a comoving, pointlike Unruh-DeWitt particle detector coupled to a complex scalar field ϕ, in the (3 + 1)-dimensional cosmological de Sitter spacetime. The field-detector coupling is taken to be proportional to ϕ†ϕ. We address both conformally invariant and massless minimally coupled scalar field theories, respectively in the conformal and the Bunch-Davies vacuum. The response function integral for the massless minimal complex scalar, not surprisingly, shows divergences and accordingly we use suitable regularisation scheme to find out well behaved results. The regularised result also contains a de Sitter symmetry breaking logarithm, growing with the cosmological time. Possibility of extension of these results with the so called de Sitter α-vacua is discussed. While we find no apparent problem in computing the response function for a real scalar in these vacua, a complex scalar field is shown to contain some possible ambiguities in the detector response. The case of the minimal and nearly massless scalar field theory is also briefly discussed.

scholarly journals Quasi-normal modes and the area spectrum of a near extremal de Sitter black hole with conformally coupled scalar field

2015 ◽  
Vol 30 (11) ◽  
pp. 1550057 ◽  
Author(s):  
Sharmanthie Fernando
Keyword(s):  
Black Hole ◽  
Wave Equation ◽  
Scalar Field ◽  
Normal Modes ◽  
Type Equation ◽  
Area Spectrum ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Quasi Normal Mode

In this paper, we have studied a black hole in de Sitter space which has a conformally coupled scalar field in the background. This black hole is also known as the MTZ black hole. We have obtained exact values for the quasi-normal mode (QNM) frequencies under massless scalar field perturbations. We have demonstrated that when the black hole is near-extremal, that the wave equation for the massless scalar field simplifies to a Schrödinger type equation with the well-known Pöschl–Teller potential. We have also used sixth-order WKB approximation to compute QNM frequencies to compare with exact values obtained via the Pöschl–Teller method for comparison. As an application, we have obtained the area spectrum using modified Hods approach and show that it is equally spaced.

scholarly journals THE REAL SCALAR FIELD EQUATION FOR NARIAI BLACK HOLE IN THE 5D SCHWARZSCHILD–DE SITTER BLACK STRING SPACE

2007 ◽  
Vol 22 (24) ◽  
pp. 4451-4465 ◽  
Author(s):  
MOLIN LIU ◽  
HONGYA LIU ◽  
CHUNXIAO WANG ◽  
YONGLI PING
Keyword(s):  
Black Hole ◽  
Field Equation ◽  
Scalar Field ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Black String ◽  
Transmission Coefficients ◽  
Scalar Field Equation ◽  
Continuous Potential

The Nariai black hole, whose two horizons are lying close to each other, is an extreme and important case in the research of black hole. In this paper we study the evolution of a massless scalar field scattered around in 5D Schwarzschild–de Sitter black string space. Using the method shown by Brevik and Simonsen (2001) we solve the scalar field equation as a boundary value problem, where real boundary condition is employed. Then with convenient replacement of the 5D continuous potential by square barrier, the reflection and transmission coefficients (R, T) are obtained. At last, we also compare the coefficients with the usual 4D counterpart.

scholarly journals TURBULENT INSTABILITY OF ANTI-DE SITTER SPACE–TIME

2013 ◽  
Vol 28 (22n23) ◽  
pp. 1340020 ◽  
Author(s):  
MACIEJ MALIBORSKI ◽  
ANDRZEJ ROSTWOROWSKI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Numerical Study ◽  
De Sitter Space ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
De Sitter ◽  
Field System ◽  
Technical Details

In these lecture notes, we discuss recently conjectured instability of anti-de Sitter space, resulting in gravitational collapse of a large class of arbitrarily small initial perturbations. We uncover the technical details used in the numerical study of spherically symmetric Einstein-massless scalar field system with negative cosmological constant that led to the conjectured instability.

scholarly journals QUANTUM FLUCTUATIONS FOR A SCALAR FIELD IN THE SPACE–TIME OF GRAVITATIONAL IMPLUSIVE WAVE

1998 ◽  
Vol 13 (08) ◽  
pp. 1201-1211 ◽  
Author(s):  
Y. ENGINER ◽  
M. HORTAÇSU ◽  
N. ÖZDEMIR
Keyword(s):  
Scalar Field ◽  
Gravitational Waves ◽  
Quantum Fluctuations ◽  
De Sitter Space ◽  
Space Time ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter

Quantum fluctuations for a massless scalar field in the background metric of spherical implusive gravitational waves propagating through Minkowski and de Sitter spaces are investigated. It is shown that there exist finite fluctuations for de Sitter space.

Lifshitz holographic renormalization from anti-de Sitter

2013 ◽  
Vol 91 (6) ◽  
pp. 457-459
Author(s):  
Wissam Chemissany ◽  
David Geissbühler ◽  
Jelle Hartong ◽  
Blaise Rollier
Keyword(s):  
Scalar Field ◽  
Critical Exponent ◽  
Dimensional Reduction ◽  
Dimensional Structure ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Holographic Renormalization

Lifshitz space–times with critical exponent z = 2 can be obtained by dimensional reduction of Schrödinger space–times with critical exponent z = 0. The latter space–times are asymptotically anti-de Sitter (AdS) solutions of AdS gravity coupled to an axion–dilaton system (or even just a massless scalar field). This basic observation is used to perform holographic renormalization for four-dimensional asymptotically locally Lifshitz space–times by dimensional reduction of the corresponding problem of holographic renormalization for five-dimensional asymptotically AdS space–times coupled to an axion–dilaton system. In this setup the four-dimensional structure of the Lifshitz – Fefferman-Graham expansion and the structure of the counterterm action, including the scale anomaly, will be summarized.

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