Inflation with vector fields revisited: non-Gaussianities
- 1Nanchang University
Abstract
A bstract : We revisit the resulting bispectrum of inflation with kinetic-coupled vector fields by organizing the dynamics in terms of h , which measures the vector kinetic contribution relative to that of the scalar field. We derive a low-energy effective field theory (EFT) and evaluate the bispectrum of the curvature perturbation for the large- h regime. For h ≫ 1, the entropic perturbation becomes heavy and can be integrated out; the remaining curvature mode has an imaginary sound speed and undergoes transient growth before horizon crossing. In contrast to the h ≪ 1 regime, where transfer from the vector sector persists outside the horizon and produces a local-type contribution enhanced as h2NK3 , we find that the bispectrum signals are controlled by the matching parameter x ≃ 1 . 63 Ah , where A < 1 is a numerical factor remaining dependent on the UV-to-EFT matching prescription. As a result, in addition to the known flattened-enhanced signals scaling as x ³ , a flattened-enhanced signal scaling as x ² and a pronounced local projection scaling as x are present. The bispectrum therefore distinguishes vector-supported inflationary dynamics even for an exactly isotropic background.
Versions
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BibTeX
@article{chen2026inflation,
title = {{Inflation with vector fields revisited: non-Gaussianities}},
author = {Chong-Bin Chen},
journal = {Journal of High Energy Physics},
year = {2026},
month = oct,
doi = {10.1007/jhep10(2026)064},
url = {https://link.springer.com/10.1007/JHEP10(2026)064},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Inflation with vector fields revisited: non-Gaussianities
AU - Chong-Bin Chen
PY - 2026
DA - 2026/10/07
JO - Journal of High Energy Physics
DO - 10.1007/jhep10(2026)064
UR - https://link.springer.com/10.1007/JHEP10(2026)064
AB - A bstract : We revisit the resulting bispectrum of inflation with kinetic-coupled vector fields by organizing the dynamics in terms of h , which measures the vector kinetic contribution relative to that of the scalar field. We derive a low-energy effective field theory (EFT) and evaluate the bispectrum of the curvature perturbation for the large- h regime. For h ≫ 1, the entropic perturbation becomes heavy and can be integrated out; the remaining curvature mode has an imaginary sound speed and undergoes transient growth before horizon crossing. In contrast to the h ≪ 1 regime, where transfer from the vector sector persists outside the horizon and produces a local-type contribution enhanced as h^2N_K^3 , we find that the bispectrum signals are controlled by the matching parameter x ≃ 1 . 63 Ah , where A < 1 is a numerical factor remaining dependent on the UV-to-EFT matching prescription. As a result, in addition to the known flattened-enhanced signals scaling as x ³ , a flattened-enhanced signal scaling as x ² and a pronounced local projection scaling as x are present. The bispectrum therefore distinguishes vector-supported inflationary dynamics even for an exactly isotropic background.
SN - 1029-8479
ER -