Editing Axion (section)

=== Prediction ===
In 1977, [[Roberto Peccei]] and [[Helen Quinn]] postulated a more elegant solution to the strong CP problem, the [[Peccei–Quinn theory|Peccei–Quinn mechanism]]. The idea is to effectively promote {{overline|Θ}} to a field. This is accomplished by adding a new global symmetry (called a [[Peccei–Quinn symmetry|Peccei–Quinn (PQ) symmetry]]) that becomes spontaneously broken. This results in a new particle, as shown independently by [[Frank Wilczek]]<ref>{{cite journal |last= Wilczek |first=Frank |year=1978 |journal=Physical Review Letters |volume=40 | issue=5 |pages= 279–282 |title=Problem of Strong P and T Invariance in the Presence of Instantons |doi=10.1103/PhysRevLett.40.279 |bibcode=1978PhRvL..40..279W}}</ref> and [[Steven Weinberg]],<ref>{{cite journal |last= Weinberg |first=Steven |year=1978 |journal=Physical Review Letters |volume=40 | issue=4 |pages=223–226 |title=A New Light Boson? |doi=10.1103/PhysRevLett.40.223 |bibcode=1978PhRvL..40..223W}}</ref> that fills the role of {{overline|Θ}}, naturally relaxing the CP-violation parameter to zero. Wilczek named this new hypothesized particle the "axion" after a [[Axion (brand)|brand of laundry detergent]] because it "cleaned up" a problem,<ref>{{cite news |last=Overbye |first=Dennis |date=17 June 2020 |title=Seeking dark matter, they detected another mystery |newspaper=[[The New York Times]] |url=https://www.nytimes.com/2020/06/17/science/xenon-axions-neutrinos-tritium.html}}</ref><ref name="WilczekQuanta2016" /> while Weinberg called it "the higglet". Weinberg later agreed to adopt Wilczek's name for the particle.<ref name="WilczekQuanta2016">{{cite magazine |last=Wilczek |first=Frank |author-link=Frank Wilczek |date=7 January 2016 |title=Time's (almost) reversible arrow |magazine=[[Quanta Magazine]] |url=https://www.quantamagazine.org/how-axions-may-explain-times-arrow-20160107/ |access-date=17 June 2020}}</ref> Because it has a non-zero mass, the axion is a [[pseudo-Nambu–Goldstone boson]].<ref>{{cite arXiv|eprint=hep-ph/0309143v1 |last1=Miller |first1=D. J. |last2=Nevzorov |first2=R. |title=The Peccei-Quinn Axion in the Next-to-Minimal Supersymmetric Standard Model |year=2003 }}</ref>