Cosmological perturbations in \bar{QCD}- inflation. Estimates confronting the observations, including BICEP2

TL;DR

This paper proposes a novel inflationary model based on a strongly coupled QCD-like gauge theory where quantum topological effects drive a de Sitter phase, making specific predictions for observable cosmological parameters.

Contribution

It introduces a new inflation scenario where the inflaton is an auxiliary field from topological sectors of a QCD-like theory, linking gauge dynamics to inflationary observables.

Findings

Estimated number of e-folds as ~100 based on gauge coupling

Predicted tensor tilt n_t ≈ -0.02 consistent with observations

Predicted small running of spectral indices ~10^{-4}

Abstract

We discuss a new scenario for early cosmology, when inflationary de Sitter phase dynamically emergent. This genuine quantum effect occurs as a result of dynamics of the topologically nontrivial sectors in a (conjectured) strongly coupled QCD- like gauge theory with scale ${\Lambda_{\overline{\mathrm{QCD}}}} \sim 10^{17} $ GeV in expanding universe. Inflaton in this ${\overline{\mathrm{QCD}}}$- inflation framework is an auxiliary non-propagating field, similar to an effective field known to emerge in topologically ordered condensed matter systems. Number of e-folds in the ${\overline{\mathrm{QCD}}}$-inflation framework is determined by the gauge coupling constant at the moment of inflation, and estimated as $N_{\rm inf}\sim \alpha^{-2}(H_0)\sim 10^2$. We analyze the equation of state in this framework at the end of inflation in terms of the gauge dynamics and confront our estimates with observations. We make predictions for the tensor tilt, $n_t \simeq -0.02$, the running of the tensor tilt $\alpha_t= {\partial n_t}/{\partial \ln k}\sim \alpha^4(H_0)\sim 10^{-4}$ and the running for the spectral index $\alpha_s= {\partial n_s}/{\partial \ln k}\sim \alpha^4(H_0)\sim 10^{-4}$ in terms of the same gauge coupling constant $\alpha(H_0)$, which is fixed in our framework by recent BICEP2 measurements of the tensor fraction $r\simeq 0.2$.