Non-linear equation of motion for higher curvature semiclassical gravity
We derive the non-linear semiclassical equation of motion for a general diffeomorphism-invariant theory of gravity by leveraging the thermodynamic properties of closed causal horizons. Our work employs two complementary approaches. The first approach utilizes perturbative quantum gravity applied to...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-02-01
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| Series: | Physics Letters B |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0370269325000243 |
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| Summary: | We derive the non-linear semiclassical equation of motion for a general diffeomorphism-invariant theory of gravity by leveraging the thermodynamic properties of closed causal horizons. Our work employs two complementary approaches. The first approach utilizes perturbative quantum gravity applied to a Rindler horizon. The result is then mapped to a stretched light cone, which can be understood as a union of Rindler planes. Here, we adopt the semiclassical physical process formulation, encapsulated by 〈Q〉=TδSgen where the heat-flux 〈Q〉 is related to the expectation value of stress-energy tensor Tab and Sgen is the generalized entropy. The second approach introduces a “higher curvature” Raychaudhuri equation, where the vanishing of the quantum expansion Θ pointwise as required by restricted quantum focusing establishes an equilibrium condition, δSgen=0, at the null boundary of a causal diamond. While previous studies have only derived the linearized semiclassical equation of motion for higher curvature gravity, our work resolves this limitation by providing a fully non-linear formulation without invoking holography. |
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| ISSN: | 0370-2693 |