Large primordial non-Gaussianity from transient turns in Higgs-R2 inflation
Abstract
We investigate the generation of primordial non-Gaussianities in multifield Higgs--R2 inflation, focusing on the effects of transient turning trajectories in the hyperbolic field space manifold. We compute the full bispectrum without relying on slow-roll or local approximations and follow the complete superhorizon evolution of curvature and isocurvature perturbations. We show that transient turns efficiently transfer isocurvature fluctuations into the adiabatic sector, generating sizeable local non-Gaussianities. For a benchmark Higgs nonminimal coupling ξh = 0.1 and quartic coupling λ= 10−10, we obtain fNLloc≃ −17.7. As the Higgs nonminimal coupling increases, the turning rate is progressively suppressed and the model approaches the effective single-field attractor, recovering the Maldacena consistency relation fNL→ 0.0159. Comparing our predictions with current CMB constraints, we find that primordial non-Gaussianity provides a sensitive probe of the Higgs nonminimal coupling and can significantly restrict the viable parameter space of the model.
Versions
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BibTeX
@misc{pineda2026large,
title = {{Large primordial non-Gaussianity from transient turns in Higgs-$R^2$ inflation}},
author = {Flavio Pineda and Luis O. Pimentel},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.18095},
eprint = {2606.18095},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.18095},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Large primordial non-Gaussianity from transient turns in Higgs-R^2 inflation
AU - Flavio Pineda
AU - Luis O. Pimentel
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2606.18095
UR - https://arxiv.org/abs/2606.18095
AB - We investigate the generation of primordial non-Gaussianities in multifield Higgs--R^2 inflation, focusing on the effects of transient turning trajectories in the hyperbolic field space manifold. We compute the full bispectrum without relying on slow-roll or local approximations and follow the complete superhorizon evolution of curvature and isocurvature perturbations. We show that transient turns efficiently transfer isocurvature fluctuations into the adiabatic sector, generating sizeable local non-Gaussianities. For a benchmark Higgs nonminimal coupling ξ_h = 0.1 and quartic coupling λ= 10^−10, we obtain f_NL^loc≃ −17.7. As the Higgs nonminimal coupling increases, the turning rate is progressively suppressed and the model approaches the effective single-field attractor, recovering the Maldacena consistency relation f_NL→ 0.0159. Comparing our predictions with current CMB constraints, we find that primordial non-Gaussianity provides a sensitive probe of the Higgs nonminimal coupling and can significantly restrict the viable parameter space of the model.
ER -