A bstract Pure gravity in AdS 3 is a theory of boundary excitations, most simply expressed as a constrained free scalar with an improved stress tensor that is needed to match the BrownHenneaux central charge. Excising a finite part of AdS gives rise to a static gauge NambuGoto action for the boundary graviton. We show that this is the $$ T\overline{T} $$ T T ¯ deformation of the infinite volume theory, as the effect of the improvement term on the deformed action can be absorbed into a field redefinition. The classical gravitational stress tensor is reproduced order by order by the $$ T\overline{T} $$ T T ¯ trace equation. We calculate the finite volume energy spectrum in static gauge and find that the trace equation imposes sufficient constraints on the ordering ambiguities to guarantee agreement with the lightcone gauge prediction. The correlation functions, however, are not completely fixed by the trace equation. We show how both the gravitational action and the $$ T\overline{T} $$ T T ¯ deformation allow for finite improvement terms, and we match these to the undetermined total derivative terms in Zamolodchikov’s point splitting definition of the $$ T\overline{T} $$ T T ¯ operator.
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This content will become publicly available on November 1, 2024
Backreaction and order reduction in initially contracting models of the Universe
The semiclassical backreaction equations are solved in closed RobertsonWalker
spacetimes containing a positive cosmological constant and a conformally coupled
massive scalar field. Renormalization of the stressenergy tensor results in higher
derivative terms that can lead to solutions that vary on much shorter time scales
than the solutions that would occur if the higher derivative terms were not present.
These extra solutions can be eliminated through the use of order reduction. Four
different methods of order reduction are investigated. These are first applied to the
case when only conformally invariant fields, with and without classical radiation,
are present. Then they are applied to the massive conformally coupled scalar field.
The effects of different adiabatic vacuum states for the massive field are considered.
It is found that if enough particles are produced, then the Universe collapses to a
final singularity. Otherwise it undergoes a bounce, but at a smaller value of the scale
factor (for the models considered) than occurs for the classical de Sitter solution. The
stressenergy tensor incorporates both particle production and vacuum polarization
effects. An analysis of the energy density of the massive field is done to determine
when the contribution from the particles dominates.
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 NSFPAR ID:
 10503394
 Publisher / Repository:
 Physical Review D
 Date Published:
 Journal Name:
 Physical Review D
 Volume:
 108
 Issue:
 10
 ISSN:
 24700010
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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