Phase Transitions in the Early Universe
As we move backwards in time towards the moment of creation, prior to one hundredth of a second, the Universe becomes hotter and denser until matter actually changes its phase, that is, it changes its form and properties.
An everyday analogue familiar to all is simply water..
At the classical level of the electroweak theory, the mass terms of the quarks and gauge bosons vanish in the high-temperature symmetric phase.
In the phase transition their mass terms, which are proportional to the vacuum expectation value of the Higgs field, become non-vanishing..
Phase transitions occur when the thermodynamic free energy of a system is non-analytic for some choice of thermodynamic variables (cf. phases).
This condition generally stems from the interactions of a large number of particles in a system, and does not appear in systems that are small..
Vacuum energy is an underlying background energy that exists in space throughout the entire Universe.
The vacuum energy is a special case of zero-point energy that relates to the quantum vacuum.
Unsolved problem in physics: Why does the zero-point energy of the vacuum not cause a large cosmological constant?.
Supercool subtleties of cosmological phase transitions Abstract.
We investigate rarely explored details of supercooled cosmological rst-order phase transitions at the electroweak scale, which may lead to strong gravitational wave signals or explain the cosmic baryon asymmetry.
In zero temperature equilibrium QFT, the vacuum expectation values are fixed and it is unnecessary to consider their space time dependent behaviour.
During a cosmic phase transition however, the vacuum expectation value can evolve with space and time. 4.1.
Coleman–Weinberg potential .
The Universe underwent several cosmological transitions in rapid succession shortly after the Big Bang, according to standard predictions in particle physics and cosmology [1{7].
Cosmological transitions are particularly interesting if they are rst-order phase transitions, proceeding through the nucleation and coalescence of bubbles [8{11].
The study of cosmic phase transitions are of central interest in modern cosmology.
In the standard model of cosmology the Universe begins in a very hot state, right after at the end of inflation via the process of reheating/preheating, and cools to its present temperature as the Universe expands.
