A density spike on astrophysical scales from an N-field waterfall transition
Hybrid inflation models are especially interesting as they lead to a spike in the density power spectrum on small scales, compared to the CMB, while also satisfying current bounds on tensor modes. Here we study hybrid inflation with N waterfall fields sharing a global SO(N) symmetry. The inclusion o...
| Main Authors: | , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
Elsevier
2015
|
| Online Access: | http://hdl.handle.net/1721.1/98205 https://orcid.org/0000-0001-7964-8587 https://orcid.org/0000-0002-3850-3688 |
| _version_ | 1826216179659702272 |
|---|---|
| author | Halpern, Illan F. Joss, Matthew Albert Henry Sfakianakis, Evangelos I. Hertzberg, Mark Peter |
| author2 | Massachusetts Institute of Technology. Center for Theoretical Physics |
| author_facet | Massachusetts Institute of Technology. Center for Theoretical Physics Halpern, Illan F. Joss, Matthew Albert Henry Sfakianakis, Evangelos I. Hertzberg, Mark Peter |
| author_sort | Halpern, Illan F. |
| collection | MIT |
| description | Hybrid inflation models are especially interesting as they lead to a spike in the density power spectrum on small scales, compared to the CMB, while also satisfying current bounds on tensor modes. Here we study hybrid inflation with N waterfall fields sharing a global SO(N) symmetry. The inclusion of many waterfall fields has the obvious advantage of avoiding topologically stable defects for N>3. We find that it also has another advantage: it is easier to engineer models that can simultaneously (i) be compatible with constraints on the primordial spectral index, which tends to otherwise disfavor hybrid models, and (ii) produce a spike on astrophysically large length scales. The latter may have significant consequences, possibly seeding the formation of astrophysically large black holes. We calculate correlation functions of the time-delay, a measure of density perturbations, produced by the waterfall fields, as a convergent power series in both 1/N and the field's correlation function Δ(x). We show that for large N, the two-point function is 〈δt(x)δt(0)〉 ∝ Δ[superscript 2](|x|)/N and the three-point function is 〈δt(x)δt(y)δt(0)〉 ∝ Δ(|x−y|)Δ(|x|)Δ(|y|)/N[superscript 2]. In accordance with the central limit theorem, the density perturbations on the scale of the spike are Gaussian for large N and non-Gaussian for small N. |
| first_indexed | 2024-09-23T16:43:33Z |
| format | Article |
| id | mit-1721.1/98205 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:43:33Z |
| publishDate | 2015 |
| publisher | Elsevier |
| record_format | dspace |
| spelling | mit-1721.1/982052022-10-03T07:50:53Z A density spike on astrophysical scales from an N-field waterfall transition Halpern, Illan F. Joss, Matthew Albert Henry Sfakianakis, Evangelos I. Hertzberg, Mark Peter Massachusetts Institute of Technology. Center for Theoretical Physics Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Massachusetts Institute of Technology. Department of Physics Halpern, Illan F. Hertzberg, Mark Peter Joss, Matthew Albert Henry Sfakianakis, Evangelos I. Hybrid inflation models are especially interesting as they lead to a spike in the density power spectrum on small scales, compared to the CMB, while also satisfying current bounds on tensor modes. Here we study hybrid inflation with N waterfall fields sharing a global SO(N) symmetry. The inclusion of many waterfall fields has the obvious advantage of avoiding topologically stable defects for N>3. We find that it also has another advantage: it is easier to engineer models that can simultaneously (i) be compatible with constraints on the primordial spectral index, which tends to otherwise disfavor hybrid models, and (ii) produce a spike on astrophysically large length scales. The latter may have significant consequences, possibly seeding the formation of astrophysically large black holes. We calculate correlation functions of the time-delay, a measure of density perturbations, produced by the waterfall fields, as a convergent power series in both 1/N and the field's correlation function Δ(x). We show that for large N, the two-point function is 〈δt(x)δt(0)〉 ∝ Δ[superscript 2](|x|)/N and the three-point function is 〈δt(x)δt(y)δt(0)〉 ∝ Δ(|x−y|)Δ(|x|)Δ(|y|)/N[superscript 2]. In accordance with the central limit theorem, the density perturbations on the scale of the spike are Gaussian for large N and non-Gaussian for small N. United States. Dept. of Energy (Contract DE-SC00012567) Massachusetts Institute of Technology. Undergraduate Research Opportunities Program University of Illinois at Urbana-Champaign (Fortner Fellowship) 2015-08-24T16:10:24Z 2015-08-24T16:10:24Z 2015-07 2015-06 Article http://purl.org/eprint/type/JournalArticle 03702693 http://hdl.handle.net/1721.1/98205 Halpern, Illan F., Mark P. Hertzberg, Matthew A. Joss, and Evangelos I. Sfakianakis. “A Density Spike on Astrophysical Scales from an N-Field Waterfall Transition.” Physics Letters B 748 (September 2015): 132–143. https://orcid.org/0000-0001-7964-8587 https://orcid.org/0000-0002-3850-3688 en_US http://dx.doi.org/10.1016/j.physletb.2015.06.076 Physics Letters B Creative Commons Attribution http://creativecommons.org/licenses/by/4.0/ application/pdf Elsevier Elsevier |
| spellingShingle | Halpern, Illan F. Joss, Matthew Albert Henry Sfakianakis, Evangelos I. Hertzberg, Mark Peter A density spike on astrophysical scales from an N-field waterfall transition |
| title | A density spike on astrophysical scales from an N-field waterfall transition |
| title_full | A density spike on astrophysical scales from an N-field waterfall transition |
| title_fullStr | A density spike on astrophysical scales from an N-field waterfall transition |
| title_full_unstemmed | A density spike on astrophysical scales from an N-field waterfall transition |
| title_short | A density spike on astrophysical scales from an N-field waterfall transition |
| title_sort | density spike on astrophysical scales from an n field waterfall transition |
| url | http://hdl.handle.net/1721.1/98205 https://orcid.org/0000-0001-7964-8587 https://orcid.org/0000-0002-3850-3688 |
| work_keys_str_mv | AT halpernillanf adensityspikeonastrophysicalscalesfromannfieldwaterfalltransition AT jossmatthewalberthenry adensityspikeonastrophysicalscalesfromannfieldwaterfalltransition AT sfakianakisevangelosi adensityspikeonastrophysicalscalesfromannfieldwaterfalltransition AT hertzbergmarkpeter adensityspikeonastrophysicalscalesfromannfieldwaterfalltransition AT halpernillanf densityspikeonastrophysicalscalesfromannfieldwaterfalltransition AT jossmatthewalberthenry densityspikeonastrophysicalscalesfromannfieldwaterfalltransition AT sfakianakisevangelosi densityspikeonastrophysicalscalesfromannfieldwaterfalltransition AT hertzbergmarkpeter densityspikeonastrophysicalscalesfromannfieldwaterfalltransition |