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 Light in dielectric media and scalar fields in a de Sitter spacetime

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
I. A. Pedrosa ◽  
B. F. Ramos ◽  
K. Bakke
Keyword(s):  
Scalar Field ◽  
Coherent States ◽  
Scalar Fields ◽  
Dielectric Medium ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Expectation Values ◽  
Dielectric Media ◽  
Sitter Spacetime ◽  
Constant Rate

AbstractIn the present work we discuss the behavior of light in a linear dielectric medium with a time-varying electric permittivity that increases exponentially at a constant rate and of a scalar field in a de Sitter spacetime, in both the classical and quantum contexts. Notably, we find that the behavior of these two systems are identical and can be described by similar Hamiltonians. By using the Lewis–Riesenfeld invariant method together with Fock states we solve the time-dependent Schrödinger equation for this problem and use its solutions to construct coherent states for the scalar field. Finally, we employ both the Fock and coherent states to evaluate some important properties of the quantized scalar field, such as expectation values of the amplitude and momentum of each mode their variances and the respective uncertainty principle.

scholarly journals Massless scalar field in de Sitter spacetime: unitary quantum time evolution

2013 ◽  
Vol 30 (7) ◽  
pp. 075015 ◽  
Author(s):  
Jerónimo Cortez ◽  
Daniel Martín-de Blas ◽  
Guillermo A Mena Marugán ◽  
José M Velhinho
Keyword(s):  
Scalar Field ◽  
Time Evolution ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Quantum Time ◽  
Sitter Spacetime

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 A General Method for Transforming Nonphysical Configurations in BPS States

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
J. R. L. Santos ◽  
A. de Souza Dutra ◽  
O. C. Winter ◽  
R. A. C. Correa
Keyword(s):  
Scalar Field ◽  
Condensed Matter ◽  
Equations Of Motion ◽  
Cosmological Parameters ◽  
Topological Defects ◽  
Scalar Fields ◽  
Complex Scalar ◽  
Complex Scalar Field ◽  
Bps States ◽  
General Method

In this work, we apply the so-called BPS method in order to obtain topological defects for a complex scalar field Lagrangian introduced by Trullinger and Subbaswamy. The BPS approach led us to compute new analytical solutions for this model. In our investigation, we found analytical configurations which satisfy the BPS first-order differential equations but do not obey the equations of motion of the model. Such defects were named nonphysical ones. In order to recover the physical meaning of these defects, we proposed a procedure which can transform them into BPS states of new scalar field models. The new models here founded were applied in the context of hybrid cosmological scenarios, where we derived cosmological parameters compatible with the observed Universe. Such a methodology opens a new window to connect different two scalar fields systems and can be implemented in several distinct applications such as Bloch Branes, Lorentz and Symmetry Breaking Scenarios, Q-Balls, Oscillons, Cosmological Contexts, and Condensed Matter Systems.

scholarly journals AMPLITUDE OF COULOMB SCATTERING FOR CHARGED SCALAR FIELD IN DE SITTER SPACETIME

2010 ◽  
Vol 25 (20) ◽  
pp. 1679-1687 ◽  
Author(s):  
COSMIN CRUCEAN
Keyword(s):  
Scalar Field ◽  
Gordon Equation ◽  
Coulomb Scattering ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Scattering Process ◽  
Charged Scalar ◽  
Sitter Spacetime ◽  
Klein Gordon ◽  
Charged Scalar Field

The scattering of a charged scalar field on Coulomb potential is studied using solutions of the Klein–Gordon equation which have a definite momentum. One obtains that the modulus of momentum is not conserved in the scattering process on de Sitter space.

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