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#### Quantum Effects of the Conformal Anomaly in a 2D Model of Gravitational Collapse

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2303.15397.pdf

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JHEP08(2023)223.pdf

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##### Citation

Mottola, E., Chandra, M., Manca, G. M., & Sorkin, E. (2023). Quantum Effects of
the Conformal Anomaly in a 2D Model of Gravitational Collapse.* ournal of High Energy Physics,*
*2023*(08): 223. doi:10.1007/JHEP08(2023)223.

Cite as: https://hdl.handle.net/21.11116/0000-000D-D699-5

##### Abstract

The macroscopic effects of the quantum conformal anomaly are evaluated in a

simplified two-dimensional model of gravitational collapse. The effective

action and stress tensor of the anomaly can be expressed in a local quadratic

form by the introduction of a scalar conformalon field which satisfies a linear

wave equation. A wide class of non-vacuum initial state conditions is generated

by different solutions of this equation. An interesting subclass of solutions

corresponds to initial states that give rise to an arbitrarily large

semi-classical stress tensor on the future horizon of the black hole formed in

classical collapse. These lead to modification and suppression of Hawking

radiation at late times after the collapse, and potentially large backreaction

effects on the horizon scale due to the conformal anomaly. The probability of

non-vacuum initial conditions large enough to produce these effects is

estimated from the Gaussian vacuum wave functional in the Schrodinger

representation and shown to be of order 1. These results indicate that quantum

effects of the conformal anomaly in non-vacuum states are relevant for

gravitational collapse in the effective theory of gravity in four dimensions as

well.

simplified two-dimensional model of gravitational collapse. The effective

action and stress tensor of the anomaly can be expressed in a local quadratic

form by the introduction of a scalar conformalon field which satisfies a linear

wave equation. A wide class of non-vacuum initial state conditions is generated

by different solutions of this equation. An interesting subclass of solutions

corresponds to initial states that give rise to an arbitrarily large

semi-classical stress tensor on the future horizon of the black hole formed in

classical collapse. These lead to modification and suppression of Hawking

radiation at late times after the collapse, and potentially large backreaction

effects on the horizon scale due to the conformal anomaly. The probability of

non-vacuum initial conditions large enough to produce these effects is

estimated from the Gaussian vacuum wave functional in the Schrodinger

representation and shown to be of order 1. These results indicate that quantum

effects of the conformal anomaly in non-vacuum states are relevant for

gravitational collapse in the effective theory of gravity in four dimensions as

well.