Santhosh Kumar, G; Kuriakose, V C(Plenum Publishing Corporation, June 22, 1999)
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Abstract:
The present work is an attempt to explain particle production in the
early univese. We argue that nonzero values of the stress-energy tensor
evaluated in squeezed vacuum state can be due to particle production and
this supports the concept of particle production from zero-point quantum
fluctuations. In the present calculation we use the squeezed coherent state
introduced by Fan and Xiao [7]. The vacuum expectation values of stressenergy
tensor defined prior to any dynamics in the background gravitational
field give all information about particle production. Squeezing of the vacuum
is achieved by means of the background gravitational field, which plays the
role of a parametric amplifier [8]. The present calculation shows that the
vacuum expectation value of the energy density and pressure contain terms
in addition to the classical zero-point energy terms. The calculation of the
particle production probability shows that the probability increases as the
squeezing parameter increases, reaches a maximum value, and then decreases.
Description:
International Journal of Theoretical Physics, Vol. 39, No. 2, 2000