Classicality of Stochastic Noise Away From Quasi-de Sitter Inflation
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866912083935756288 |
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| author | Noorbala, Mahdiyar |
| author_facet | Noorbala, Mahdiyar |
| contents | It is well known that a coarse-grained scalar field living on a de~Sitter (dS) background exhibits classical stochastic behavior, driven by a noise whose amplitude is set by the Hubble constant $H$. The coarse-graining is achieved by discarding wave numbers larger than a cutoff $σa H$ and demanding that $σ\ll 1$. Similar results hold for quasi-dS space, where the equation of state parameter $w$ is close to $-1$. Here we present exact expressions for the noise amplitude of a free massless field on an inflationary background with constant $w < -1/3$. We find that a classical stochastic behavior can emerge for $-5/3 < w < -1/3$. Furthermore, as we move away from $w = -1$ and approach $w = -1/3$, the constraint $σ\ll 1$ is relaxed and larger cutoffs ($σ\sim 1$) become feasible, too. However, in general the amplitude of the noise depends on $σ$, except in the quasi-dS regime $w \approx -1$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2408_11640 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Classicality of Stochastic Noise Away From Quasi-de Sitter Inflation Noorbala, Mahdiyar High Energy Physics - Theory Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology It is well known that a coarse-grained scalar field living on a de~Sitter (dS) background exhibits classical stochastic behavior, driven by a noise whose amplitude is set by the Hubble constant $H$. The coarse-graining is achieved by discarding wave numbers larger than a cutoff $σa H$ and demanding that $σ\ll 1$. Similar results hold for quasi-dS space, where the equation of state parameter $w$ is close to $-1$. Here we present exact expressions for the noise amplitude of a free massless field on an inflationary background with constant $w < -1/3$. We find that a classical stochastic behavior can emerge for $-5/3 < w < -1/3$. Furthermore, as we move away from $w = -1$ and approach $w = -1/3$, the constraint $σ\ll 1$ is relaxed and larger cutoffs ($σ\sim 1$) become feasible, too. However, in general the amplitude of the noise depends on $σ$, except in the quasi-dS regime $w \approx -1$. |
| title | Classicality of Stochastic Noise Away From Quasi-de Sitter Inflation |
| topic | High Energy Physics - Theory Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2408.11640 |