The spatial gauge-dependence of single-field inflationary bispectra
In single-field inflationary models the bispectra are usually given in the ζ-gauge, because its temporal part leads to the super-horizon conservation of fluctuations. However, this property is independent of the choice of spatial gauge, so in this letter we explore this freedom. We compute the varia...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2022-05-01
|
| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0370269322001526 |
| _version_ | 1828741996304400384 |
|---|---|
| author | Ermis Mitsou Jaiyul Yoo |
| author_facet | Ermis Mitsou Jaiyul Yoo |
| author_sort | Ermis Mitsou |
| collection | DOAJ |
| description | In single-field inflationary models the bispectra are usually given in the ζ-gauge, because its temporal part leads to the super-horizon conservation of fluctuations. However, this property is independent of the choice of spatial gauge, so in this letter we explore this freedom. We compute the variation of the bispectra under the most general spatial gauge transformation that is globally defined and privileges no point, direction or scale. In the squeezed configuration we then obtain a generalization of the classic ζ-gauge consistency relations, which we also derive through the ‘large diffeomorphism’ approach for all four bispectra. At leading order in the long wave-number the transformation only affects the case where the long mode is a scalar. The first effect is a shift of the tilt factor, so that one can significantly reduce the amplitude of that contribution. Secondly, there is now an extra term depending on the triangle shape, the same as in solid inflation, which is due to the fact that the 3-metric has a scalar anisotropy in generic spatial gauge. At next-to-leading order there is no variation, so the conformal consistency relations of the ζ-gauge are preserved. |
| first_indexed | 2024-04-13T01:11:22Z |
| format | Article |
| id | doaj.art-aa730ec065534d21b94d651b73cb127a |
| institution | Directory Open Access Journal |
| issn | 0370-2693 |
| language | English |
| last_indexed | 2024-04-13T01:11:22Z |
| publishDate | 2022-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Physics Letters B |
| spelling | doaj.art-aa730ec065534d21b94d651b73cb127a2022-12-22T03:09:09ZengElsevierPhysics Letters B0370-26932022-05-01828137018The spatial gauge-dependence of single-field inflationary bispectraErmis Mitsou0Jaiyul Yoo1Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zurich, CH–8057 Zurich, Switzerland; Corresponding authors.Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zurich, CH–8057 Zurich, Switzerland; Physics Institute, University of Zurich, Winterthurerstrasse 190, CH–8057, Zurich, Switzerland; Corresponding authors.In single-field inflationary models the bispectra are usually given in the ζ-gauge, because its temporal part leads to the super-horizon conservation of fluctuations. However, this property is independent of the choice of spatial gauge, so in this letter we explore this freedom. We compute the variation of the bispectra under the most general spatial gauge transformation that is globally defined and privileges no point, direction or scale. In the squeezed configuration we then obtain a generalization of the classic ζ-gauge consistency relations, which we also derive through the ‘large diffeomorphism’ approach for all four bispectra. At leading order in the long wave-number the transformation only affects the case where the long mode is a scalar. The first effect is a shift of the tilt factor, so that one can significantly reduce the amplitude of that contribution. Secondly, there is now an extra term depending on the triangle shape, the same as in solid inflation, which is due to the fact that the 3-metric has a scalar anisotropy in generic spatial gauge. At next-to-leading order there is no variation, so the conformal consistency relations of the ζ-gauge are preserved.http://www.sciencedirect.com/science/article/pii/S0370269322001526 |
| spellingShingle | Ermis Mitsou Jaiyul Yoo The spatial gauge-dependence of single-field inflationary bispectra Physics Letters B |
| title | The spatial gauge-dependence of single-field inflationary bispectra |
| title_full | The spatial gauge-dependence of single-field inflationary bispectra |
| title_fullStr | The spatial gauge-dependence of single-field inflationary bispectra |
| title_full_unstemmed | The spatial gauge-dependence of single-field inflationary bispectra |
| title_short | The spatial gauge-dependence of single-field inflationary bispectra |
| title_sort | spatial gauge dependence of single field inflationary bispectra |
| url | http://www.sciencedirect.com/science/article/pii/S0370269322001526 |
| work_keys_str_mv | AT ermismitsou thespatialgaugedependenceofsinglefieldinflationarybispectra AT jaiyulyoo thespatialgaugedependenceofsinglefieldinflationarybispectra AT ermismitsou spatialgaugedependenceofsinglefieldinflationarybispectra AT jaiyulyoo spatialgaugedependenceofsinglefieldinflationarybispectra |