Particle Production in Higher-Dimensional Universe with Time-Dependent $$\Lambda$$ and G

2021 ◽  
Author(s):  
S. Surendra Singh ◽  
S. Kiranmala Chanu
Keyword(s):  
Particle Production ◽  
Time Dependent ◽  
Higher Dimensional

scholarly journals TIME-DEPENDENT EXTRA DIMENSION AND HIGHER-DIMENSIONAL MODIFICATIONS TO THE MATTER CONTENT IN FRW SPACETIMES

2010 ◽  
Vol 25 (10) ◽  
pp. 781-792 ◽  
Author(s):  
M. LA CAMERA
Keyword(s):  
Coordinate System ◽  
Extra Dimension ◽  
Scalar Function ◽  
Matter Content ◽  
Time Dependent ◽  
Higher Dimensional

In this work we suggest that higher-dimensional modifications to the matter content in FRW spacetimes can be obtained not only, as first considered by Ponce de Leon, referring to "moving" 4D hypersurfaces non-orthogonal to the time-dependent extra dimension of an embedding 5D manifold, but also referring to "fixed" 4D hypersurfaces orthogonal to a suitable scalar function which defines a static foliation of the 5D manifold and takes the role of the extra dimension in a suitable coordinate system. Results obtained in each approach crucially depend on the method used to identify the 4D metric of our brane universe from the 5D metric of the bulk manifold.

scholarly journals Cosmological particle production and pairwise hotspots on the CMB

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Jeong Han Kim ◽  
Soubhik Kumar ◽  
Adam Martin ◽  
Yuhsin Tsai
Keyword(s):  
Particle Production ◽  
Heavy Particle ◽  
Power Spectra ◽  
Time Dependent ◽  
Position Space ◽  
Spatial Profile ◽  
Heavy Particles ◽  
Curvature Perturbation ◽  
Cold Spots ◽  
Cmb Fluctuations

Abstract Heavy particles with masses much bigger than the inflationary Hubble scale H*, can get non-adiabatically pair produced during inflation through their couplings to the inflaton. If such couplings give rise to time-dependent masses for the heavy particles, then following their production, the heavy particles modify the curvature perturbation around their locations in a time-dependent and scale non-invariant manner. This results into a non-trivial spatial profile of the curvature perturbation that is preserved on superhorizon scales and eventually generates localized hot or cold spots on the CMB. We explore this phenomenon by studying the inflationary production of heavy scalars and derive the final temperature profile of the spots on the CMB by taking into account the subhorizon evolution, focusing in particular on the parameter space where pairwise hot spots (PHS) arise. When the heavy scalar has an $$ \mathcal{O} $$ O (1) coupling to the inflaton, we show that for an idealized situation where the dominant background to the PHS signal comes from the standard CMB fluctuations themselves, a simple position space search based on applying a temperature cut, can be sensitive to heavy particle masses M0/H* ∼ $$ \mathcal{O} $$ O (100). The corresponding PHS signal also modifies the CMB power spectra and bispectra, although the corrections are below (outside) the sensitivity of current measurements (searches).

scholarly journals Demystifying the constancy of the Ermakov–Lewis invariant for a time-dependent oscillator

2018 ◽  
Vol 33 (07n08) ◽  
pp. 1830005 ◽  
Author(s):  
T. Padmanabhan
Keyword(s):  
Harmonic Oscillator ◽  
Physical Interpretation ◽  
Particle Production ◽  
Conserved Quantity ◽  
Time Dependent ◽  
Quantum Fields ◽  
Expanding Universe ◽  
Simple Physical Interpretation ◽  
Schwinger Effect ◽  
External Time

It is well known that the time-dependent harmonic oscillator (TDHO) possesses a conserved quantity, usually called Ermakov–Lewis invariant. I provide a simple physical interpretation of this invariant as well as a whole family of related invariants. This interpretation does not seem to have been noticed in the literature before. The procedure also allows one to tackle some key conceptual issues which arise in the study of quantum fields in the external, time-dependent backgrounds like in the case of particle production in an expanding universe and Schwinger effect.

scholarly journals Beauty is more attractive: particle production andmoduli trapping with higher dimensional interaction

2014 ◽  
Vol 2014 (1) ◽  
Author(s):  
Seishi Enomoto ◽  
Satoshi Iida ◽  
Nobuhiro Maekawa ◽  
Tomohiro Matsuda
Keyword(s):  
Particle Production ◽  
Dimensional Interaction ◽  
Higher Dimensional

scholarly journals Time-dependent particle production and particle number in cosmological de Sitter space

2015 ◽  
Vol 24 (05) ◽  
pp. 1550031 ◽  
Author(s):  
Eric Greenwood
Keyword(s):  
Particle Production ◽  
Occupation Number ◽  
Operator Method ◽  
Large Mass ◽  
Invariant Operator ◽  
Time Dependent ◽  
De Sitter ◽  
Power Law Distribution ◽  
Bogolyubov Transformation ◽  
Thermal Distribution

In this paper, we consider the occupation number of induced quasi-particles which are produced during a time-dependent process using three different methods: Instantaneous diagonalization, the usual Bogolyubov transformation between two different vacua (more precisely the instantaneous vacuum and the so-called adiabatic vacuum), and the Unruh–DeWitt detector methods. Here we consider the Hamiltonian for a time-dependent Harmonic oscillator, where both the mass and frequency are taken to be time-dependent. From the Hamiltonian we derive the occupation number of the induced quasi-particles using the invariant operator method. In deriving the occupation number we also point out and make the connection between the Functional Schrödinger formalism, quantum kinetic equation, and Bogolyubov transformation between two different Fock space basis at equal times and explain the role in which the invariant operator method plays. As a concrete example, we consider particle production in the flat FRW chart of de Sitter spacetime. Here we show that the different methods lead to different results: The instantaneous diagonalization method leads to a power law distribution, while the usual Bogolyubov transformation and Unruh–DeWitt detector methods both lead to thermal distributions (however the dimensionality of the results are not consistent with the dimensionality of the problem; the usual Bogolyubov transformation method implies that the dimensionality is 3D while the Unruh–DeWitt detector method implies that the dimensionality is 7D/2). It is shown that the source of the descrepency between the instantaneous diagonalization and usual Bogolyubov methods is the fact that there is no notion of well-defined particles in the out vacuum due to a divergent term. In the usual Bogolyubov method, this divergent term cancels leading to the thermal distribution, while in the instantaneous diagonalization method there is no such cancelation leading to the power law distribution. However, to obtain the thermal distribution in the usual Bogolyubov method, one must use the large mass limit. On physical grounds, one should expect that only the modes which have been allowed to sample the horizon would be thermal, thus in the large mass limit these modes are well within the horizon and, even though they do grow, they remain well within the horizon due to the mass. Thus, one should not expect a thermal distribution since the modes will not have a chance to thermalize.

scholarly journals Particle production in time-dependent gravitational fields: the expanding mass shell

2003 ◽  
Vol 20 (11) ◽  
pp. 2337-2353 ◽  
Author(s):  
Sabine Hossenfelder ◽  
Dominik J Schwarz ◽  
Walter Greiner
Keyword(s):  
Particle Production ◽  
Mass Shell ◽  
Time Dependent ◽  
Gravitational Fields
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