QCD surprises: strong CP problem, neutrino mass, Dark Matter and Dark Energy

TL;DR

This paper proposes a novel explanation for neutrino mass, Dark Matter, and Dark Energy based on QCD within the Standard Model, avoiding the need for axions and suggesting neutrino condensates as dark matter candidates.

Contribution

It introduces a new QCD-based framework that explains neutrino mass, dark matter, and dark energy without axions, and proposes neutrino condensates as dark matter candidates.

Findings

Neutrino condensates can serve as dark matter candidates.

Neutrinos can form Cooper pairs, leading to collective low-energy states.

The strong CP problem is resolved without fundamental axions.

Abstract

An unexpected explanation for neutrino mass, Dark Matter (DM) and Dark Energy (DE) from genuine Quantum Chromodynamics (QCD) of the Standard Model (SM) is proposed here, while the strong CP problem is resolved without any need to account for fundamental axions. We suggest that the neutrino sector can be in a double phase in the Universe: i) relativistic neutrinos, belonging to the SM; ii) non-relativistic condensate of Majorana neutrinos. The condensate of neutrinos can provide an attractive alternative candidate for the DM, being in a cold coherent state. We will explain how neutrinos, combining into Cooper pairs, can form collective low-energy degrees of freedom, hence providing a strongly motivated candidate for the QCD (composite) axion.