Non-Gaussianities and tensor-to-scalar ratio in non-local R 2-like inflation
Abstract In this paper we will study R 2-like inflation in a non-local modification of gravity which contains quadratic in Ricci scalar and Weyl tensor terms with analytic infinite derivative form-factors in the action. It is known that the inflationary solution of the local R + R 2 gravity remains...
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doaj-91bb10dfd9f1497ab582133ae88b5ede2020-11-25T03:16:28ZengSpringerOpenJournal of High Energy Physics1029-84792020-06-012020614010.1007/JHEP06(2020)152Non-Gaussianities and tensor-to-scalar ratio in non-local R 2-like inflationAlexey S. Koshelev0K. Sravan Kumar1Anupam Mazumdar2Alexei A. Starobinsky3Departamento de Física, Centro de Matemática e Aplicaçoes (CMA-UBI), Universidade da Beira InteriorVan Swinderen Institute, University of GroningenVan Swinderen Institute, University of GroningenL.D. Landau Institute for Theoretical Physics RASAbstract In this paper we will study R 2-like inflation in a non-local modification of gravity which contains quadratic in Ricci scalar and Weyl tensor terms with analytic infinite derivative form-factors in the action. It is known that the inflationary solution of the local R + R 2 gravity remains a particular exact solution in this model. It was shown earlier that the power spectrum of scalar perturbations generated during inflation in the non-local setup remains the same as in the local R + R 2 inflation, whereas the power spectrum of tensor perturbations gets modified due to the non-local Weyl tensor squared term. In the present paper we go beyond 2-point correlators and compute the non-Gaussian parameter f NL related to 3-point correlations generated during inflation, which we found to be different from those in the original local inflationary model and scenarios alike based on a local gravity. We evaluate non-local corrections to the scalar bi-spectrum which give non-zero contributions to squeezed, equilateral and orthogonal configurations. We show that f NL ∼ O(1) with an arbitrary sign is achievable in this model based on the choice of form-factors and the scale of non-locality. We present the predictions for the tensor-to-scalar ratio, r, and the tensor tilt, n t . In contrast to standard inflation in a local gravity, here the possibility n t > 0 is not excluded. Thus, future CMB data can probe non-local behaviour of gravity at high space-time curvatures.http://link.springer.com/article/10.1007/JHEP06(2020)152Cosmology of Theories beyond the SMModels of Quantum Gravity |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Alexey S. Koshelev K. Sravan Kumar Anupam Mazumdar Alexei A. Starobinsky |
spellingShingle |
Alexey S. Koshelev K. Sravan Kumar Anupam Mazumdar Alexei A. Starobinsky Non-Gaussianities and tensor-to-scalar ratio in non-local R 2-like inflation Journal of High Energy Physics Cosmology of Theories beyond the SM Models of Quantum Gravity |
author_facet |
Alexey S. Koshelev K. Sravan Kumar Anupam Mazumdar Alexei A. Starobinsky |
author_sort |
Alexey S. Koshelev |
title |
Non-Gaussianities and tensor-to-scalar ratio in non-local R 2-like inflation |
title_short |
Non-Gaussianities and tensor-to-scalar ratio in non-local R 2-like inflation |
title_full |
Non-Gaussianities and tensor-to-scalar ratio in non-local R 2-like inflation |
title_fullStr |
Non-Gaussianities and tensor-to-scalar ratio in non-local R 2-like inflation |
title_full_unstemmed |
Non-Gaussianities and tensor-to-scalar ratio in non-local R 2-like inflation |
title_sort |
non-gaussianities and tensor-to-scalar ratio in non-local r 2-like inflation |
publisher |
SpringerOpen |
series |
Journal of High Energy Physics |
issn |
1029-8479 |
publishDate |
2020-06-01 |
description |
Abstract In this paper we will study R 2-like inflation in a non-local modification of gravity which contains quadratic in Ricci scalar and Weyl tensor terms with analytic infinite derivative form-factors in the action. It is known that the inflationary solution of the local R + R 2 gravity remains a particular exact solution in this model. It was shown earlier that the power spectrum of scalar perturbations generated during inflation in the non-local setup remains the same as in the local R + R 2 inflation, whereas the power spectrum of tensor perturbations gets modified due to the non-local Weyl tensor squared term. In the present paper we go beyond 2-point correlators and compute the non-Gaussian parameter f NL related to 3-point correlations generated during inflation, which we found to be different from those in the original local inflationary model and scenarios alike based on a local gravity. We evaluate non-local corrections to the scalar bi-spectrum which give non-zero contributions to squeezed, equilateral and orthogonal configurations. We show that f NL ∼ O(1) with an arbitrary sign is achievable in this model based on the choice of form-factors and the scale of non-locality. We present the predictions for the tensor-to-scalar ratio, r, and the tensor tilt, n t . In contrast to standard inflation in a local gravity, here the possibility n t > 0 is not excluded. Thus, future CMB data can probe non-local behaviour of gravity at high space-time curvatures. |
topic |
Cosmology of Theories beyond the SM Models of Quantum Gravity |
url |
http://link.springer.com/article/10.1007/JHEP06(2020)152 |
work_keys_str_mv |
AT alexeyskoshelev nongaussianitiesandtensortoscalarratioinnonlocalr2likeinflation AT ksravankumar nongaussianitiesandtensortoscalarratioinnonlocalr2likeinflation AT anupammazumdar nongaussianitiesandtensortoscalarratioinnonlocalr2likeinflation AT alexeiastarobinsky nongaussianitiesandtensortoscalarratioinnonlocalr2likeinflation |
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