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Constraints on non-minimal coupling from quantum cosmology
Quantum cosmology is investigated in a de Sitter minisuperspace model with a
quantized scalar field non-minimally coupled to curvature. Quantum states of
the scalar field must satisfy the regularity condition, which requires that the
probability of field fluctuations should not increase with their amplitude. We
show that this condition imposes constraints on the allowed values of the
curvature coupling parameter . This is a surprising result, since the
field dynamics depends only on the combination , where is the
field mass and is the curvature, and does not depend on
separately.Comment: v1, 15 pages, 2 figures; v2, 19 pages, 5 figures, version accepted
for publication in JCAP, discussion added to incorporate with a hilltop
potentia
The doomsday of black hole evaporation
By assuming simultaneously the unitarity of the Hawking evaporation and the
universality of Bekenstein entropy bound as well as the validity of cosmic
censorship conjecture, we have found that the black hole evaporation rate could
evolve from the usual inverse square law in black hole mass into a constant
evaporation rate near the end of the Hawking evaporation before quantum gravity
could come into play, inferring a slightly longer lifetime for lighter black
holes.Comment: 7 pages, 1 figur
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