Can Horndeski Genesis be nonpathological?
Abstract We present a minimal setup within the framework of Horndeski gravity that can describe a nonpathological Genesis scenario, namely, the strong-coupling energy scale is always well above the classical energy scale. Our setup allows for a fully stable transition to the kination epoch, during w...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2025-08-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | https://doi.org/10.1007/JHEP08(2025)044 |
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| author | Han Gil Choi Pavel Petrov Masahide Yamaguchi |
| author_facet | Han Gil Choi Pavel Petrov Masahide Yamaguchi |
| author_sort | Han Gil Choi |
| collection | DOAJ |
| description | Abstract We present a minimal setup within the framework of Horndeski gravity that can describe a nonpathological Genesis scenario, namely, the strong-coupling energy scale is always well above the classical energy scale. Our setup allows for a fully stable transition to the kination epoch, during which General Relativity (GR) is restored. This Genesis scenario circumvents the no-go theorem at the cost of encountering the risk of strong coupling in the past. Interestingly, our scenario admits two different regimes for the background solution for Hubble parameter at the Genesis stage: power-law behavior and manifestly non-power-law behavior. We explicitly show that, in both regimes, our model remains within unitarity bounds. In most cases, the tensor spectrum is blue-tilted. Then, we adopt a mechanism with a spectator field that allows for a red-tilted scalar power spectrum. We also suggest a deformation of the model that enables us to achieve sufficiently small values for the tensor-to-scalar ratio. Finally, we discuss the geodesic (in)completeness of the current model. |
| format | Article |
| id | doaj-art-40aa329bf5cf4dfa857e056f8c76d574 |
| institution | Kabale University |
| issn | 1029-8479 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-40aa329bf5cf4dfa857e056f8c76d5742025-08-20T03:45:40ZengSpringerOpenJournal of High Energy Physics1029-84792025-08-012025815810.1007/JHEP08(2025)044Can Horndeski Genesis be nonpathological?Han Gil Choi0Pavel Petrov1Masahide Yamaguchi2Cosmology, Gravity and Astroparticle Physics Group, Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS)Cosmology, Gravity and Astroparticle Physics Group, Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS)Cosmology, Gravity and Astroparticle Physics Group, Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS)Abstract We present a minimal setup within the framework of Horndeski gravity that can describe a nonpathological Genesis scenario, namely, the strong-coupling energy scale is always well above the classical energy scale. Our setup allows for a fully stable transition to the kination epoch, during which General Relativity (GR) is restored. This Genesis scenario circumvents the no-go theorem at the cost of encountering the risk of strong coupling in the past. Interestingly, our scenario admits two different regimes for the background solution for Hubble parameter at the Genesis stage: power-law behavior and manifestly non-power-law behavior. We explicitly show that, in both regimes, our model remains within unitarity bounds. In most cases, the tensor spectrum is blue-tilted. Then, we adopt a mechanism with a spectator field that allows for a red-tilted scalar power spectrum. We also suggest a deformation of the model that enables us to achieve sufficiently small values for the tensor-to-scalar ratio. Finally, we discuss the geodesic (in)completeness of the current model.https://doi.org/10.1007/JHEP08(2025)044Classical Theories of GravityCosmological modelsEffective Field TheoriesSpacetime Singularities |
| spellingShingle | Han Gil Choi Pavel Petrov Masahide Yamaguchi Can Horndeski Genesis be nonpathological? Journal of High Energy Physics Classical Theories of Gravity Cosmological models Effective Field Theories Spacetime Singularities |
| title | Can Horndeski Genesis be nonpathological? |
| title_full | Can Horndeski Genesis be nonpathological? |
| title_fullStr | Can Horndeski Genesis be nonpathological? |
| title_full_unstemmed | Can Horndeski Genesis be nonpathological? |
| title_short | Can Horndeski Genesis be nonpathological? |
| title_sort | can horndeski genesis be nonpathological |
| topic | Classical Theories of Gravity Cosmological models Effective Field Theories Spacetime Singularities |
| url | https://doi.org/10.1007/JHEP08(2025)044 |
| work_keys_str_mv | AT hangilchoi canhorndeskigenesisbenonpathological AT pavelpetrov canhorndeskigenesisbenonpathological AT masahideyamaguchi canhorndeskigenesisbenonpathological |