English

$\tilde\xi$-attractors in metric-affine gravity

General Relativity and Quantum Cosmology 2025-07-03 v4 Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology

Abstract

We propose a new class of inflationary attractors in metric-affine gravity. Such class features a non-minimal coupling ξ~Ω(ϕ)\tilde\xi \, \Omega(\phi) with the Holst invariant R~\tilde{\cal R} and an inflaton potential proportional to Ω(ϕ)2\Omega(\phi)^2. The attractor behaviour of the class takes place with two combined strong coupling limits. The first limit is realized at large ξ~\tilde\xi, which makes the theory equivalent to a R~2\tilde{\cal R}^2 model. Then, the second limit considers a very small Barbero-Immirzi parameter which leads the inflationary predictions of the R~2\tilde{\cal R}^2 model towards the ones of Starobinsky inflation. Because of the analogy with the renown ξ\xi-attractors, we label this new class as ξ~\tilde\xi-attractors.

Cite

@article{arxiv.2411.08031,
  title  = {$\tilde\xi$-attractors in metric-affine gravity},
  author = {Antonio Racioppi},
  journal= {arXiv preprint arXiv:2411.08031},
  year   = {2025}
}

Comments

v4, 18 pages, 3 figures, typos corrected in some equations, results unchanged, matches the erratum version

R2 v1 2026-06-28T19:57:28.639Z