# Generalizations of normal ordering and applications to quantization in classical backgrounds

@article{Nikoli2002GeneralizationsON, title={Generalizations of normal ordering and applications to quantization in classical backgrounds}, author={Hrvoje Nikoli{\'c}}, journal={General Relativity and Gravitation}, year={2002}, volume={37}, pages={297-311} }

A nonlocal method of extracting the positive (or the negative) frequency part of a field, based on knowledge of a 2-point function, leads to certain natural generalizations of the normal ordering of quantum fields in classical gravitational and electromagnetic backgrounds and illuminates the origin of the recently discovered nonlocalities related to a local description of particles. A local description of particle creation by gravitational backgrounds is given, with emphasis on the case of…

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