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Particle creation, renormalizability conditions and the mass-energy spectrum in gravity theories of quadratic Lagrangians
Massive scalar particle production, due to the anisotropic evolution of a
five-dimensional spacetime, is considered in the context of a quadratic
Lagrangian theory of gravity. Those particles, corresponding to field modes
with non-vanishing momentum component along the fifth dimension, are created
mostly in the neighbourhood of a singular epoch where only their high-frequency
behaviour is of considerable importance. At the 1-loop approximation level,
general renormalizability conditions on the physical quantities relevant to
particle production are derived and discussed. Exact solutions of the resulting
Klein-Gordon field equation are obtained and the mass-energy spectrum
attributed to the scalar field due to the cosmological evolution is being
investigated further. Finally, analytic expressions regarding the number and
the energy density of the created particles at late times, are also derived and
discussed.Comment: LaTeX file, 23 page