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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2411.06975 |
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| _version_ | 1866911239799570432 |
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| author | Han, Yu Chen, Long |
| author_facet | Han, Yu Chen, Long |
| contents | In Ref. [1], it was claimed that in the spatially flat cosmological case there exists a unique conserved measure (up to normalization) on the $(ϕ,\dotϕ)$ phase space for scalar field with $m^2ϕ^2$ potential by finding a unique solution to the differential equation (44) (in Ref. [1]) in the low-energy regime. In Ref. [2], it was also claimed that a unique solution to the same differential equation was found in the high-energy regime and using this solution the authors calculated the expected total number of e-folds of inflation. In this comment, we reanalyze the differential equation (44) and obtain general solutions both in the low-energy and high-energy regime, which can include the solution in Ref. [1] and the solution in Ref. [2] as a special case in the corresponding energy regime. In this way, we find that following the constructions in Ref. [1] there actually exist infinitely many nonequivalent conserved measures for the scalar-field cosmology with $m^2ϕ^2$ potential on the $(ϕ,\dotϕ)$ phase space. Moreover, through specific calculations, we also show that different choices of measures can lead to quite different predictions of the expected total number of e-folds of inflation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_06975 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Comment on "Attractor solutions in scalar-field cosmology" and "How many e-folds should we expect from high-scale inflation?" Han, Yu Chen, Long General Relativity and Quantum Cosmology In Ref. [1], it was claimed that in the spatially flat cosmological case there exists a unique conserved measure (up to normalization) on the $(ϕ,\dotϕ)$ phase space for scalar field with $m^2ϕ^2$ potential by finding a unique solution to the differential equation (44) (in Ref. [1]) in the low-energy regime. In Ref. [2], it was also claimed that a unique solution to the same differential equation was found in the high-energy regime and using this solution the authors calculated the expected total number of e-folds of inflation. In this comment, we reanalyze the differential equation (44) and obtain general solutions both in the low-energy and high-energy regime, which can include the solution in Ref. [1] and the solution in Ref. [2] as a special case in the corresponding energy regime. In this way, we find that following the constructions in Ref. [1] there actually exist infinitely many nonequivalent conserved measures for the scalar-field cosmology with $m^2ϕ^2$ potential on the $(ϕ,\dotϕ)$ phase space. Moreover, through specific calculations, we also show that different choices of measures can lead to quite different predictions of the expected total number of e-folds of inflation. |
| title | Comment on "Attractor solutions in scalar-field cosmology" and "How many e-folds should we expect from high-scale inflation?" |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2411.06975 |