When did vacuum energy of the Universe become cosmological constant?

TL;DR

This paper investigates the transition of vacuum energy into a cosmological constant following a quark-gluon phase transition, suggesting dark energy may originate from vacuum energy established during early Universe symmetry breaking.

Contribution

It proposes that vacuum energy became a cosmological constant after the quark-gluon phase transition, linking dark energy to early Universe quantum chromodynamics effects.

Findings

Vacuum energy hardened into a cosmological constant after the phase transition.

Quantum chromodynamical vacuum with pseudogoldstone bosons existed at T~150 MeV.

Modern vacuum energy value is calculated using Zel'dovich's formula.

Abstract

A quark-gluon phase transition in the Universe is researched after which vacuum (dark) energy has hardened and become cosmological constant. Before this a vacuum component of the Universe was changing by jumps during phase transitions since vacuum condensates of quantum fields carried a negative contribution in its positive density energy. This quintessence period of the Universe life took place during the first parts of a second when our Universe was losing high symmetry. Using Zel'dovich's formula the modern value of vacuum energy is also calculated. It is shown that a quantum chromodynamical vacuum which is characterized by pseudogoldstone bosons existed definitely when temperature of the Universe was T~150 MeV. Therefore there is a large probability that dark energy is vacuum energy.