Faizal, Mir (2009) Perturbative Quantum Gravity and YangMills Theories in de Sitter Spacetime. PhD thesis, University of York.

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Abstract
This thesis consists of three parts. In the rst part we review the quantization of YangMills theories and perturbative quantum gravity in curved spacetime. In the second part we calculate the Feynman propagators of the Faddeev Popov ghosts for YangMills theories and perturbative quantum gravity in the covariant gauge. In the third part we investigate the physical equivalence of covariant Wightman graviton twopoint function with the physical graviton twopoint function. The Feynman propagators of the FaddeevPopov ghosts for YangMills theories and perturbative quantum gravity in the covariant gauge are infrared (IR) divergent in de Sitter spacetime. We point out, that if we regularize these divergences by introducing a nite mass and take the zero mass limit at the end, then the modes responsible for these divergences will not contribute to loop diagrams in computations of timeordered products in either YangMills theories or perturbative quantum gravity. We thus nd eective Feynman propagators for ghosts in YangMills theories and perturbative quantum gravity by subtracting out these divergent modes. It is known that the covariant graviton twopoint function in de Sitter spacetime is infrared divergent for some choices of gauge parameters. On the other hand it is also known that there are no infrared problems for the physical graviton twopoint function obtained by xing all gauge degrees of freedom, in global coordinates. We show that the covariant Wightman graviton twopoint function is equivalent to the physical one in the sense that they result in the same twopoint function of any local gaugeinvariant quantity. Thus any infrared divergence in the Wightman graviton twopoint function in de Sitter spacetime can only be an gauge artefact.
Item Type:  Thesis (PhD) 

Academic Units:  The University of York > Mathematics (York) 
Depositing User:  Mr Mir Faizal 
Date Deposited:  26 Aug 2011 09:54 
Last Modified:  08 Aug 2013 08:46 
URI:  http://etheses.whiterose.ac.uk/id/eprint/1486 