Non-Gaussianity in rapid-turn multi-field inflation
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| Format: | Preprint |
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2023
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| _version_ | 1866917699073867776 |
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| author | Iarygina, Oksana Marsh, M. C. David Salinas, Gustavo |
| author_facet | Iarygina, Oksana Marsh, M. C. David Salinas, Gustavo |
| contents | We show that theories of inflation with multiple, rapidly turning fields can generate large amounts of non-Gaussianity. We consider a general theory with two fields, an arbitrary field-space metric, and a potential that supports sustained, rapidly turning field trajectories. Our analysis accounts for non-zero field cross-correlation and does not fix the power spectra of curvature and isocurvature perturbations to be equal at horizon crossing. Using the $δN$ formalism, we derive a novel, analytical formula for bispectrum generated from multi-field mixing on super-horizon scales. Rapid-turn inflation can produce a bispectrum with several potentially large contributions that are not necessarily of the local shape. We exemplify the applicability of our formula with a fully explicit model and show that the new contributions indeed can generate a large amplitude of local non-Gaussianity, $f_{\rm NL}^{\rm loc}\sim {\cal O}(1)$. These results will be important when interpreting the outcomes of future observations. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2303_14156 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Non-Gaussianity in rapid-turn multi-field inflation Iarygina, Oksana Marsh, M. C. David Salinas, Gustavo Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory We show that theories of inflation with multiple, rapidly turning fields can generate large amounts of non-Gaussianity. We consider a general theory with two fields, an arbitrary field-space metric, and a potential that supports sustained, rapidly turning field trajectories. Our analysis accounts for non-zero field cross-correlation and does not fix the power spectra of curvature and isocurvature perturbations to be equal at horizon crossing. Using the $δN$ formalism, we derive a novel, analytical formula for bispectrum generated from multi-field mixing on super-horizon scales. Rapid-turn inflation can produce a bispectrum with several potentially large contributions that are not necessarily of the local shape. We exemplify the applicability of our formula with a fully explicit model and show that the new contributions indeed can generate a large amplitude of local non-Gaussianity, $f_{\rm NL}^{\rm loc}\sim {\cal O}(1)$. These results will be important when interpreting the outcomes of future observations. |
| title | Non-Gaussianity in rapid-turn multi-field inflation |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2303.14156 |