Localized Steps toward ACT-Favored Inflation
High Energy Physics - Phenomenology
2026-04-03 v1 Cosmology and Nongalactic Astrophysics
Abstract
Recent ACT measurements favor a scalar spectral index n_s larger than the Planck value, posing a challenge to many single-field slow-roll inflation models. We show that a smooth, localized step in the inflaton potential can shift the predicted values of n_s and r by displacing the field value at which the CMB pivot scale exits the horizon. This mechanism can move monomial and, in particular, plateau-like attractor models toward the ACT-favored region, whereas the induced shift remains insufficient in natural inflation.
Keywords
Cite
@article{arxiv.2604.02148,
title = {Localized Steps toward ACT-Favored Inflation},
author = {Kai-Ge Zhang and Chengjie Fu and Jian-Feng He and Zong-Kuan Guo},
journal= {arXiv preprint arXiv:2604.02148},
year = {2026}
}
Comments
7 pages, 3 figures