# Electroweak epoch

Part of a series on :
Physical cosmology :
Big Bang · Universe
Age of the universe
Chronology of the universe :
Early universe
Inflation · Nucleosynthesis
Backgrounds
Gravitational wave (GWB)
Microwave (CMB) · Neutrino (CNB) :
Expansion · Future
Hubble's law · Redshift
Expansion of the universe
FLRW metric · Friedmann equations
Lambda-CDM model
Future of an expanding universe
Ultimate fate of the universe :
Components · Structure
Components
Dark energy · Dark matter
Photons · Baryons
Structure
Shape of the universe
Galaxy filament · Galaxy formation
Large quasar group
Large-scale structure
Reionization · Structure formation :
Experiments
Black Hole Initiative (BHI)
BOOMERanG
Cosmic Background Explorer (COBE)
Dark Energy Survey
Planck space observatory
Sloan Digital Sky Survey (SDSS)
2dF Galaxy Redshift Survey ("2dF")
Wilkinson Microwave Anisotropy Probe (WMAP) :
Scientists
Aaronson
Alfvén
Alpher
Copernicus
de Sitter
Dicke
Ehlers
Einstein
Ellis
Friedmann
Galileo
Gamow
Guth
Hawking
Hubble
Huygens
Kepler
Lemaître
Mather
Newton
Penrose
Penzias
Rubin
Schmidt
Smoot
Suntzeff
Sunyaev
Tolman
Wilson
Zeldovich
List of cosmologists :
Subject history
Discovery of cosmic microwave background radiation
History of the Big Bang theory
Timeline of cosmological theories :
Category
Astronomy portal :
vte :
In physical cosmology, the electroweak epoch was the period in the evolution of the early universe when the temperature of the universe had fallen enough that the strong force separated from the electronuclear interaction, but was still high enough for electromagnetism and the weak interaction to remain merged into a single electroweak interaction above the critical temperature for electroweak symmetry breaking (159.5±1.5 GeV in the Standard Model of particle physics). Some cosmologists place the electroweak epoch at the start of the inflationary epoch, approximately 10$^{−36}$ seconds after the Big Bang. Others place it at approximately 10$^{−32}$ seconds after the Big Bang, when the potential energy of the inflaton field that had driven the inflation of the universe during the inflationary epoch was released, filling the universe with a dense, hot quark–gluon plasma.
Particle interactions in this phase were energetic enough to create large numbers of exotic particles, including W and Z bosons and Higgs bosons. As the universe expanded and cooled, interactions became less energetic, and when the universe was about 10$^{−12}$ seconds old, W and Z bosons ceased to be created at observable rates. The remaining W and Z bosons decayed quickly, and the weak interaction became a short-range force in the following quark epoch.
The electroweak epoch ended with an electroweak phase transition, the nature of which is unknown. Speculation in the 1990s that it may be a first order transition suggested it could source a gravitational wave background and a baryogenesis, provided the Sakharov conditions are satisfied and the Higg boson energy was below 45 GeV. Subsequent work with the Standard Model and a measurement of the Higg boson as over 114GeV, showed the transition during the electroweak epoch was not a first- or a second-order phase transition but a continuous crossover, preventing any baryogenesis, or the production of an observable gravitational wave background.
However, many extensions to the Standard Model including supersymmetry and the two-Higgs-doublet model have a first-order electroweak phase transition (but require additional CP violation).$^{:319}$