Astrophysics > Cosmology and Nongalactic Astrophysics
[Submitted on 24 Mar 2023 (v1), last revised 19 Jun 2024 (this version, v2)]
Title:Non-Gaussianity in rapid-turn multi-field inflation
View PDF HTML (experimental)Abstract: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 $\delta N$ 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.
Submission history
From: Oksana Iarygina [view email][v1] Fri, 24 Mar 2023 17:08:50 UTC (1,235 KB)
[v2] Wed, 19 Jun 2024 14:13:04 UTC (1,763 KB)
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