Details
| Original language | English |
|---|---|
| Article number | 167 |
| Number of pages | 19 |
| Journal | Journal of high energy physics |
| Volume | 2022 |
| Issue number | 8 |
| Early online date | 18 Aug 2022 |
| Publication status | Published - Aug 2022 |
Abstract
We compare the path integral for transition functions in unimodular gravity and in general relativity. In unimodular gravity the cosmological constant is a property of states that are specified at the boundaries whereas in general relativity the cosmological constant is a parameter of the action. Unimodular gravity with a nondynamical background spacetime volume element has a time variable that is canonically conjugate to the cosmological constant. Wave functions depend on time and satisfy a Schrödinger equation. On the contrary, in the covariant version of unimodular gravity with a 3-form gauge field, proposed by Henneaux and Teitelboim, wave functions are time independent and satisfy a Wheeler-DeWitt equation, as in general relativity. The 3-form gauge field integrated over spacelike hypersurfaces becomes a “cosmic time” only in the semiclassical approximation. In unimodular gravity the smallness of the observed cosmological constant has to be explained as a property of the initial state.
Keywords
- Classical Theories of Gravity, Models of Quantum Gravity
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Nuclear and High Energy Physics
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In: Journal of high energy physics, Vol. 2022, No. 8, 167, 08.2022.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - The cosmological constant as a boundary term
AU - Buchmüller, Wilfried
AU - Dragon, Norbert
N1 - Acknowledgments: We thank Klaus Fredenhagen for a helpful discussion and Marc Henneaux for comments on the manuscript.
PY - 2022/8
Y1 - 2022/8
N2 - We compare the path integral for transition functions in unimodular gravity and in general relativity. In unimodular gravity the cosmological constant is a property of states that are specified at the boundaries whereas in general relativity the cosmological constant is a parameter of the action. Unimodular gravity with a nondynamical background spacetime volume element has a time variable that is canonically conjugate to the cosmological constant. Wave functions depend on time and satisfy a Schrödinger equation. On the contrary, in the covariant version of unimodular gravity with a 3-form gauge field, proposed by Henneaux and Teitelboim, wave functions are time independent and satisfy a Wheeler-DeWitt equation, as in general relativity. The 3-form gauge field integrated over spacelike hypersurfaces becomes a “cosmic time” only in the semiclassical approximation. In unimodular gravity the smallness of the observed cosmological constant has to be explained as a property of the initial state.
AB - We compare the path integral for transition functions in unimodular gravity and in general relativity. In unimodular gravity the cosmological constant is a property of states that are specified at the boundaries whereas in general relativity the cosmological constant is a parameter of the action. Unimodular gravity with a nondynamical background spacetime volume element has a time variable that is canonically conjugate to the cosmological constant. Wave functions depend on time and satisfy a Schrödinger equation. On the contrary, in the covariant version of unimodular gravity with a 3-form gauge field, proposed by Henneaux and Teitelboim, wave functions are time independent and satisfy a Wheeler-DeWitt equation, as in general relativity. The 3-form gauge field integrated over spacelike hypersurfaces becomes a “cosmic time” only in the semiclassical approximation. In unimodular gravity the smallness of the observed cosmological constant has to be explained as a property of the initial state.
KW - Classical Theories of Gravity
KW - Models of Quantum Gravity
UR - http://www.scopus.com/inward/record.url?scp=85136507156&partnerID=8YFLogxK
U2 - 10.48550/arXiv.2203.15714
DO - 10.48550/arXiv.2203.15714
M3 - Article
AN - SCOPUS:85136507156
VL - 2022
JO - Journal of high energy physics
JF - Journal of high energy physics
SN - 1029-8479
IS - 8
M1 - 167
ER -