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Shifted hybrid realization of nonminimal Higgs inflation in light of ACT DR6 and Planck data

Nadir Ijaz*

Pirzada†

Mansoor Ur Rehman‡

  • *Contact author: nadir.ijaz@phd.unipd.it
  • †Contact author: pirzada@itp.ac.cn
  • ‡Contact author: m.rehman@iu.edu.sa
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Phys. Rev. D 114, 083529 – Published 19 October, 2026

DOI: https://doi.org/10.1103/fvm8-w8t7

Abstract

We investigate nonminimal Higgs inflation in a no-scale-inspired supergravity framework and confront its predictions with the latest cosmic microwave background (CMB) constraints from ACT DR6 and Planck. Working within a shifted hybrid inflation scenario, we construct an effective single-field description in which the grand unified theory Higgs direction serves as the inflaton after stabilization of the orthogonal scalar fields. We show that the inclusion of the leading nonrenormalizable operator in the superpotential induces a controlled deformation of the Starobinsky attractor, allowing the scalar spectral index to be shifted into the range favored by recent ACT and related CMB datasets while maintaining a small tensor-to-scalar ratio, r∼10−3–10−2. The resulting inflationary dynamics remain theoretically consistent, with controlled supergravity corrections and sub-Planckian inflaton field values. We perform a detailed numerical analysis of the model parameter space, including reheating and nonthermal leptogenesis, and identify regions that simultaneously satisfy current observational constraints and yield a viable postinflationary cosmological history.

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Phys. Rev. D 114, 083529– Published 19 October, 2026
  • Received 8 July 2026
  • Accepted 18 September 2026
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