Timelike boundaries in de Sitter JT gravity and the Gao-Wald theorem
Abstract The Gao-Wald theorem says that the Penrose diagram of de Sitter spacetime reacts to a positive energy perturbation by getting “taller”. How does this change in the presence of timelike boundaries? We study this question in two-dimensional de Sitter JT gravity coupled to conformal matter. Th...
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2025-01-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | https://doi.org/10.1007/JHEP01(2025)044 |
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| author | Gauri Batra |
| author_facet | Gauri Batra |
| author_sort | Gauri Batra |
| collection | DOAJ |
| description | Abstract The Gao-Wald theorem says that the Penrose diagram of de Sitter spacetime reacts to a positive energy perturbation by getting “taller”. How does this change in the presence of timelike boundaries? We study this question in two-dimensional de Sitter JT gravity coupled to conformal matter. The effect of the boundaries has its roots in quantum corrections to the vacuum energy of the CFT due to Casimir-like effects. We consider two different kinds of timelike boundaries, and for each kind we compute the vacuum expectation value of the matter CFT stress tensor. The stress tensor violates the null energy condition in the first case and saturates it in the second case, with each case exhibiting a negative energy density in the vacuum state. We then compute the semiclassical backreaction of this energy density and show how it can make the spacetime “fatter” or “taller” or a combination of both, depending on the regime. The spacetime getting fatter corresponds to an increase in the value of the dilaton at the horizon and hence also in the static patch horizon area in the higher-dimensional solution. We comment on the implications of our results for the quantum theories living on the timelike boundaries. |
| format | Article |
| id | doaj-art-5ff3733ee6ed48b3af7a3d8d0df20a93 |
| institution | Kabale University |
| issn | 1029-8479 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-5ff3733ee6ed48b3af7a3d8d0df20a932025-01-19T12:07:03ZengSpringerOpenJournal of High Energy Physics1029-84792025-01-012025112510.1007/JHEP01(2025)044Timelike boundaries in de Sitter JT gravity and the Gao-Wald theoremGauri Batra0Stanford Institute for Theoretical PhysicsAbstract The Gao-Wald theorem says that the Penrose diagram of de Sitter spacetime reacts to a positive energy perturbation by getting “taller”. How does this change in the presence of timelike boundaries? We study this question in two-dimensional de Sitter JT gravity coupled to conformal matter. The effect of the boundaries has its roots in quantum corrections to the vacuum energy of the CFT due to Casimir-like effects. We consider two different kinds of timelike boundaries, and for each kind we compute the vacuum expectation value of the matter CFT stress tensor. The stress tensor violates the null energy condition in the first case and saturates it in the second case, with each case exhibiting a negative energy density in the vacuum state. We then compute the semiclassical backreaction of this energy density and show how it can make the spacetime “fatter” or “taller” or a combination of both, depending on the regime. The spacetime getting fatter corresponds to an increase in the value of the dilaton at the horizon and hence also in the static patch horizon area in the higher-dimensional solution. We comment on the implications of our results for the quantum theories living on the timelike boundaries.https://doi.org/10.1007/JHEP01(2025)0442D GravityCosmological modelsde Sitter spaceGauge-Gravity Correspondence |
| spellingShingle | Gauri Batra Timelike boundaries in de Sitter JT gravity and the Gao-Wald theorem Journal of High Energy Physics 2D Gravity Cosmological models de Sitter space Gauge-Gravity Correspondence |
| title | Timelike boundaries in de Sitter JT gravity and the Gao-Wald theorem |
| title_full | Timelike boundaries in de Sitter JT gravity and the Gao-Wald theorem |
| title_fullStr | Timelike boundaries in de Sitter JT gravity and the Gao-Wald theorem |
| title_full_unstemmed | Timelike boundaries in de Sitter JT gravity and the Gao-Wald theorem |
| title_short | Timelike boundaries in de Sitter JT gravity and the Gao-Wald theorem |
| title_sort | timelike boundaries in de sitter jt gravity and the gao wald theorem |
| topic | 2D Gravity Cosmological models de Sitter space Gauge-Gravity Correspondence |
| url | https://doi.org/10.1007/JHEP01(2025)044 |
| work_keys_str_mv | AT gauribatra timelikeboundariesindesitterjtgravityandthegaowaldtheorem |