English

Primordial non-Gaussianity constraints on dissipative inflation

Cosmology and Nongalactic Astrophysics 2026-03-17 v1

Abstract

Dissipative effects appear in many early-Universe scenarios, yet their universal observational signatures and systematic confrontation with data remain largely unexplored. We employ the Open Effective Field Theory of Inflation (Open EFToI) to consistently incorporate dissipative and stochastic effects while preserving scale invariance. Dissipation enhances specific interaction channels of the Goldstone mode, generating distinctive primordial non-Gaussian signatures, beyond those generically produced by standard EFToI. In the weak-dissipation regime, this includes folded bispectrum shapes observationally more favoured than both the equilateral and orthogonal templates. Using the Modal bispectrum pipeline with the Planck CMB data, we obtain the likelihood and derive the first model-independent bounds on early-Universe dissipation. We find a marginalised upper bound on the dissipation scale γ384H\gamma \leq 384\,H and a lower bound on the sound speed cs0.38c_s \geq 0.38 at 95%95\% confidence level. The maximum likelihood for best-fit models reveals a degeneracy between γ\gamma and csc_s. These results open a model-independent window for probing departures from minimal inflation and discriminating between early-Universe scenarios with stochastic noise and dissipative effects.

Keywords

Cite

@article{arxiv.2603.13473,
  title  = {Primordial non-Gaussianity constraints on dissipative inflation},
  author = {Santiago Agüí Salcedo and Thomas Colas and Petar Suman and Bowei Zhang and James Fergusson and E. P. S. Shellard},
  journal= {arXiv preprint arXiv:2603.13473},
  year   = {2026}
}

Comments

6 pages without appendices, 4 figures