scholarly journals Corrections to the Friedmann equations from loop quantum gravity for a universe with a free scalar field

2008 ◽  
Vol 78 (6) ◽  
Author(s):  
Victor Taveras
Keyword(s):  
Scalar Field ◽  
Quantum Gravity ◽  
Loop Quantum Gravity ◽  
Friedmann Equations ◽  
Free Scalar

scholarly journals Gravity quantized: Loop quantum gravity with a scalar field

2010 ◽  
Vol 82 (10) ◽  
Author(s):  
Marcin Domagała ◽  
Kristina Giesel ◽  
Wojciech Kamiński ◽  
Jerzy Lewandowski
Keyword(s):  
Scalar Field ◽  
Quantum Gravity ◽  
Loop Quantum Gravity

scholarly journals Noncommutative Friedmann equations in effective LQC

2020 ◽  
Vol 29 (06) ◽  
pp. 2050039
Author(s):  
Luis Rey Díaz-Barrón ◽  
Abraham Espinoza-García ◽  
S. Pérez-Payán ◽  
J. Socorro
Keyword(s):  
Scalar Field ◽  
Effective Potential ◽  
Quantum Cosmology ◽  
Equations Of Motion ◽  
Loop Quantum Cosmology ◽  
Friedmann Equations ◽  
Noncommutative Version ◽  
Previous Proposal ◽  
Free Scalar ◽  
Raychaudhuri Equations

In this work, we construct a noncommutative version of the Friedmann equations in the framework of effective loop quantum cosmology, extending and applying the ideas presented in a previous proposal by some of the authors. The model under consideration is a flat FRW spacetime with a free scalar field. First, noncommutativity in the momentum sector is introduced. We establish the noncommutative equations of motion and obtain the corresponding exact solutions. Such solutions indicate that the bounce is preserved, in particular, the energy density is the same as in the standard LQC. We also construct an extension of the modified Friedmann equations arising in effective LQC which incorporates corrections due to noncommutativity, and argue that an effective potential is induced. This, in turn, leads us to investigate the possibility of an inflationary era. Finally, we obtain the Friedmann and the Raychaudhuri equations when implementing noncommutativity in the configuration sector. In this case, no effective potential is induced.

Polymer quantization effects on gauge-flation

2018 ◽  
Vol 15 (10) ◽  
pp. 1850169
Author(s):  
M. Mardaani ◽  
K. Nozari
Keyword(s):  
Hilbert Space ◽  
Quantum Mechanics ◽  
Quantum Gravity ◽  
Gauge Field ◽  
Quantum Cosmology ◽  
Loop Quantum Gravity ◽  
Loop Quantum Cosmology ◽  
Abelian Gauge ◽  
Friedmann Equations ◽  
Cosmological Inflation

Polymer quantum mechanics, as a non-standard representation of quantum mechanics, is based on a symmetric sector of loop quantum gravity known as loop quantum cosmology. In this work, by analyzing the Hamiltonian and Friedmann equations in the standard Hilbert space and polymer Hilbert space, we show that polymer quantization is a successful formalism for a non-Abelian gauge field driving the cosmological inflation, the so-called gauge-flation, in order to remove initial singularity and also keeping the inflationary trajectories in this model as attractors of dynamics after the bounce.

scholarly journals Loop quantum gravity coupled to a scalar field

2016 ◽  
Vol 93 (2) ◽  
Author(s):  
Jerzy Lewandowski ◽  
Hanno Sahlmann
Keyword(s):  
Scalar Field ◽  
Quantum Gravity ◽  
Loop Quantum Gravity

QUANTUM CYLINDRICAL WAVES AND PARAMETRIZED FIELD THEORY

2006 ◽  
Vol 15 (10) ◽  
pp. 1743-1752 ◽  
Author(s):  
MADHAVAN VARADARAJAN
Keyword(s):  
Field Theory ◽  
Scalar Field ◽  
Quantum Gravity ◽  
Flat Space ◽  
Space Time ◽  
Gravitational Fields ◽  
Cylindrical Waves ◽  
Cylindrically Symmetric ◽  
Gravity Effects ◽  
Free Scalar

In this article, we review some illustrative results in the study of two related toy models for quantum gravity, namely cylindrical waves (which are cylindrically symmetric gravitational fields)and parametrized field theory (which is just free scalar field theory on a flat space–time in generally covariant disguise). In the former, we focus on the phenomenon of unexpected large quantum gravity effects in regions of weak classical gravitational fields and on an analysis of causality in a quantum geometry. In the latter, we focus on Dirac quantization, argue that this is related to the unitary implementability of free scalar field evolution along curved foliations of the flat space–time and review the relevant results for unitary implementability.

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