Electroweak epoch

{{Short description|Period in the evolution of the early universe}}

{{Physical cosmology}}

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{{Cite journal

|author=D'Onofrio, Michela |author2=Rummukainen, Kari

|title=Standard model cross-over on the lattice

|journal=Phys. Rev. D

|volume=93

|year=2016

|number=2

|page=025003

|doi=10.1103/PhysRevD.93.025003

|arxiv=1508.07161

|bibcode=2016PhRvD..93b5003D

|hdl=10138/159845

|s2cid=119261776

|hdl-access=free

}}

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.{{cite book |last=Ryden |first=B. |title=Introduction to Cosmology |page=196 |publisher=Addison-Wesley |year=2003 |isbn=0-8053-8912-1 }}{{cite book | last=Allday | first=Jonathan | title=Quarks, Leptons and the Big Bang| publisher=Taylor & Francis | year=2002 | isbn=978-0-7503-0806-9 |page=334}} 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.[http://nicadd.niu.edu/~bterzic/PHYS652/Lecture_13.pdf Lecture 13: History of the Very Early Universe] {{Webarchive|url=https://web.archive.org/web/20120327225133/http://nicadd.niu.edu/~bterzic/PHYS652/Lecture_13.pdf |date=2012-03-27 }}, Dr. Balša Terzić, Northern Illinois Center for Accelerator and Detector Development

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.{{citation needed|date=March 2020}} 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,{{Cite journal

|author=L. D. McLerran |author2=M. E. Shaposhnikov |author3=N. Turok |author4=M. B. Voloshin

|title=Why the baryon asymmetry of the universe is approximately 10**-10

|journal=Phys. Lett. B

|volume=256

|year=1991

|pages=451–456

|doi=10.1016/0370-2693(91)91794-V

|arxiv=

}}{{Cite journal

|author=Morrissey, David E. |author2=Ramsey-Musolf, Michael J.

|title=Electroweak baryogenesis

|journal=New J. Phys.

|volume=14

|year=2012

|issue=12

|page=12500

|doi=10.1088/1367-2630/14/12/125003

|arxiv=1206.2942

|bibcode=2012NJPh...14l5003M

|s2cid=119230032

}} provided the Sakharov conditions are satisfied{{cite journal

| author=A. D. Sakharov

| year=1967

| title=Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe

| journal=Journal of Experimental and Theoretical Physics Letters

| volume=5

| pages=24–27

| url=http://www.jetpletters.ac.ru/ps/1643/article_25089.shtml

| doi=

| author-link=Andrei Sakharov

| access-date=2020-07-14

| archive-date=2019-05-16

| archive-url=https://web.archive.org/web/20190516163822/http://www.jetpletters.ac.ru/ps/1643/article_25089.shtml

}} and in Russian, {{cite journal

| author=A. D. Sakharov

| year=1967

| title=Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe

| journal=ZhETF Pis'ma

| volume=5

| pages=32–35

| url=http://www.jetpletters.ac.ru/ps/808/article_12459.shtml

| doi=

| author-link=Andrei Sakharov

| access-date=2020-07-14

| archive-date=2019-06-06

| archive-url=https://web.archive.org/web/20190606082623/http://www.jetpletters.ac.ru/ps/808/article_12459.shtml

}} republished as {{cite journal

| author=A. D. Sakharov

| year=1991

| title=Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe

| journal=Soviet Physics Uspekhi

| volume=34

| pages=392–393

| language=Russian, English

| doi=10.1070/PU1991v034n05ABEH002497

| url=https://ufn.ru/en/articles/1991/5/h/

| bibcode=1991SvPhU..34..392S

| issue=5

}}

and the Higg boson energy was below 45 GeV.{{Cite journal |last=Buchmüller |first=W. |last2=Peccei |first2=R.D. |last3=Yanagida |first3=T. |date=2005-12-01 |title=LEPTOGENESIS AS THE ORIGIN OF MATTER |url=https://www.annualreviews.org/doi/10.1146/annurev.nucl.55.090704.151558 |journal=Annual Review of Nuclear and Particle Science |language=en |volume=55 |issue=1 |pages=311–355 |doi=10.1146/annurev.nucl.55.090704.151558 |issn=0163-8998|arxiv=hep-ph/0502169 }}

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,{{cite book |last1=Bergerhoff |first1=Bastian |title=Current Topics in Astrofundamental Physics: Primordial Cosmology |last2=Wetterich |first2=Christof |chapter=Electroweak Phase Transition in the Early Universe? |date=1998 |pages=211–240 |doi=10.1007/978-94-011-5046-0_6 |publisher=Springer Netherlands |language=en|arxiv=hep-ph/9611462 |isbn=978-94-010-6119-3 |s2cid=13949582 }}{{Cite journal

|author=Kajantie, Keijo

|display-authors=etal

|title=The Electroweak Phase Transition: A Non-Perturbative Analysis

|journal=Nucl. Phys. B

|year=1996

|volume=466

|issue=1–2

|pages=189–258

|doi=10.1016/0550-3213(96)00052-1

|arxiv=hep-lat/9510020

|bibcode=1996NuPhB.466..189K

|s2cid=119416033

}}

or the production of an observable gravitational wave background.{{Cite journal

|author=Caprini, Chiara

|display-authors=etal

|title=Detecting gravitational waves from cosmological phase transitions with LISA: an update

|journal=Journal of Cosmology and Astroparticle Physics

|volume=2020

|year=2020

|issue=3

|page=024

|doi=10.1088/1475-7516/2020/03/024

|arxiv=1910.13125

|bibcode=2020JCAP...03..024C

|s2cid=204950387

}}

{{Cite journal

|author=Ghiglieri, J. |author2=Jackson, G. |author3=Laine, M. |author4=Zhu, Y.

|title=Gravitational wave background from Standard Model physics: Complete leading order

|journal=Journal of High Energy Physics

|year=2020

|volume=2020

|issue=7

|page=092

|doi=10.1007/JHEP07(2020)092

|arxiv=2004.11392

|bibcode=2020JHEP...07..092G

|s2cid=216144470

}}

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).{{rp|319}}