Testing quantum gravity with primordial gravitational waves
Abstract We propose a testable alternative to inflation directly built in a very general class of ultraviolet complete theories of quantum gravity enjoying Weyl invariance. After the latter is spontaneously broken, logarithmic quantum corrections to the action make both the primordial tensor spectru...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2024-12-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | https://doi.org/10.1007/JHEP12(2024)024 |
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| _version_ | 1850254449007656960 |
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| author | Gianluca Calcagni Leonardo Modesto |
| author_facet | Gianluca Calcagni Leonardo Modesto |
| author_sort | Gianluca Calcagni |
| collection | DOAJ |
| description | Abstract We propose a testable alternative to inflation directly built in a very general class of ultraviolet complete theories of quantum gravity enjoying Weyl invariance. After the latter is spontaneously broken, logarithmic quantum corrections to the action make both the primordial tensor spectrum (from graviton fluctuations) and the scalar spectrum (from thermal fluctuations) quasi scale invariant. We predict a scalar spectral index n s which only depends on two parameters and is consistent with observations, a tensor index n t = 1 − n s > 0, and, if the fundamental energy scale of the theory Λ* = M Pl is of order of the Planck mass, a tensor-to-scalar ratio r 0.05 ≈ 0.01 detectable by BICEP Array and LiteBIRD in the immediate or near future, respectively, and a blue-tilted stochastic gravitational-wave background observable by DECIGO in the further future. From the observational constraint r 0.05 < 0.036, we also find the lower bound Λ* > 8.5 × 1010 GeV, much stronger than any previous one for this class of theories. |
| format | Article |
| id | doaj-art-363aa905a31f43cab4aa717edf99dbfa |
| institution | OA Journals |
| issn | 1029-8479 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-363aa905a31f43cab4aa717edf99dbfa2025-08-20T01:57:08ZengSpringerOpenJournal of High Energy Physics1029-84792024-12-0120241214110.1007/JHEP12(2024)024Testing quantum gravity with primordial gravitational wavesGianluca Calcagni0Leonardo Modesto1Instituto de Estructura de la Materia, CSICDipartimento di Fisica, Università di CagliariAbstract We propose a testable alternative to inflation directly built in a very general class of ultraviolet complete theories of quantum gravity enjoying Weyl invariance. After the latter is spontaneously broken, logarithmic quantum corrections to the action make both the primordial tensor spectrum (from graviton fluctuations) and the scalar spectrum (from thermal fluctuations) quasi scale invariant. We predict a scalar spectral index n s which only depends on two parameters and is consistent with observations, a tensor index n t = 1 − n s > 0, and, if the fundamental energy scale of the theory Λ* = M Pl is of order of the Planck mass, a tensor-to-scalar ratio r 0.05 ≈ 0.01 detectable by BICEP Array and LiteBIRD in the immediate or near future, respectively, and a blue-tilted stochastic gravitational-wave background observable by DECIGO in the further future. From the observational constraint r 0.05 < 0.036, we also find the lower bound Λ* > 8.5 × 1010 GeV, much stronger than any previous one for this class of theories.https://doi.org/10.1007/JHEP12(2024)024Cosmological modelsModels of Quantum Gravity |
| spellingShingle | Gianluca Calcagni Leonardo Modesto Testing quantum gravity with primordial gravitational waves Journal of High Energy Physics Cosmological models Models of Quantum Gravity |
| title | Testing quantum gravity with primordial gravitational waves |
| title_full | Testing quantum gravity with primordial gravitational waves |
| title_fullStr | Testing quantum gravity with primordial gravitational waves |
| title_full_unstemmed | Testing quantum gravity with primordial gravitational waves |
| title_short | Testing quantum gravity with primordial gravitational waves |
| title_sort | testing quantum gravity with primordial gravitational waves |
| topic | Cosmological models Models of Quantum Gravity |
| url | https://doi.org/10.1007/JHEP12(2024)024 |
| work_keys_str_mv | AT gianlucacalcagni testingquantumgravitywithprimordialgravitationalwaves AT leonardomodesto testingquantumgravitywithprimordialgravitationalwaves |