phi meson

The most common decay modes of the {{Subatomic particle|Phi meson}} meson are {{Subatomic particle|link=yes|Kaon+}}{{Subatomic particle|link=yes|Kaon-}} at {{val|48.9|0.5|u=%}}, {{Subatomic particle|link=yes|K-short0}}+{{Subatomic particle|link=yes|K-long0}} at {{val|34.2|0.4|u=%}}, and various indistinguishable mixed combinations of rho mesons and pions at {{val|15.3|0.3|u=%}}.{{cite web |last1=Nakamura |first1=K. |collaboration=Particle Data Group |year=2010 |department=Particle listings |title={{Subatomic particle|Phi meson}} |publisher=Lawrence Berkeley Laboratory |place=Lawrence, CA |url=http://pdg.lbl.gov/2010/listings/rpp2010-list-phi-1020.pdf |access-date=5 May 2017}} In all cases, it decays via the strong force. The pion channel would naïvely be the dominant decay channel because the collective mass of the pions is smaller than that of the kaons, making it energetically favorable; however, that decay route is suppressed by the OZI rule.

Technically, the quark composition of the {{Subatomic particle|Phi meson}} meson can be thought of as a mix between {{Subatomic particle|strange quark}}{{Subatomic particle|strange antiquark}}, {{Subatomic particle|link=yes|up quark}}{{Subatomic particle|link=yes|up antiquark}}, and {{Subatomic particle|link=yes|down quark}}{{Subatomic particle|link=yes|down antiquark}} states, but it is very nearly a pure {{Subatomic particle|strange quark}}{{Subatomic particle|strange antiquark}} state.{{cite report |last1=Nakamura |first1=K. |collaboration=Particle Data Group |year=2011 |title=14. Quark Model |publisher=Lawrence Berkeley Laboratory |place=Lawrence, CA |url=http://pdg.lbl.gov/2011/reviews/rpp2011-rev-quark-model.pdf |access-date=3 June 2021 }} This can be shown by deconstructing the wave function of the {{Subatomic particle|Phi meson}} into its component parts. We see that the {{Subatomic particle|Phi meson}} and {{Subatomic particle|Omega meson}} mesons are mixtures of the SU(3) wave functions as follows.

: $\backslash phi\; =\; \backslash psi\_8\backslash \; \backslash cos\backslash theta\backslash \; -\backslash \; \backslash psi\_1\backslash \; \backslash sin\backslash theta$,

: $\backslash omega\; =\; \backslash psi\_8\backslash \; \backslash sin\backslash theta\backslash \; +\backslash \; \backslash psi\_1\backslash \; \backslash cos\backslash theta$,

where

: $\backslash theta$ is the nonet mixing angle,

: $\backslash psi\_8\; =\; \backslash frac\{\backslash \; u\backslash overline\{u\}\; +\; d\backslash overline\{d\}\; -\; 2s\backslash overline\{s\}\backslash \; \}\{\; \backslash sqrt\{6\backslash \; \}\; \}~$ and

: $\backslash psi\_1\; =\; \backslash frac\{\backslash \; u\backslash overline\{u\}\; +\; d\backslash overline\{d\}\; +\; s\backslash overline\{s\}\backslash \; \}\{\; \backslash sqrt\{3\backslash \; \}\; \}\; ~.$

The mixing angle at which the components decouple completely can be calculated to be $\backslash \; \backslash arctan\backslash frac\{\; 1\; \}\{\; \backslash sqrt\{2\backslash \; \}\; \}\; \backslash approx\; 35.3^\backslash circ\; ~.$ The mixing angle of the {{Subatomic particle|Phi meson}} and {{Subatomic particle|Omega meson}} states is calculated from the masses of each state to be about 35˚, which is very close to maximum decoupling. Therefore, the {{Subatomic particle|Phi meson}} meson is nearly a pure {{Subatomic particle|strange quark}}{{Subatomic particle|strange antiquark}} state.

The existence of the {{Subatomic particle|Phi meson}} meson was first proposed by the Japanese American particle physicist, J. J. Sakurai, in 1962 as a resonance state between the {{SubatomicParticle|link=yes|Kaon0}} and the {{SubatomicParticle|link=yes|Antikaon0}}.{{cite journal |last1=Sakurai |first1=J.J. |date=December 1962 |title=Possible existence of a {{nobr| {{math|T {{=}} 0}} }} vector meson at 1020 MeV |journal=Physical Review Letters |volume=9 |issue=11 |pages=472–475 |doi=10.1103/PhysRevLett.9.472 |bibcode=1962PhRvL...9..472S |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.9.472 |access-date=5 May 2017 |url-access=subscription }} It was discovered later by {{harvp|Connolly|Hart|Lai|London|Moneti|1963}} in a 20 inch hydrogen bubble chamber at the Alternating Gradient Synchrotron (AGS) in Brookhaven National Laboratory in Upton, NY while they were studying {{SubatomicParticle|link=yes|Kaon-}}{{Subatomic particle|link=yes|Proton+}} collisions at approximately 2.23 GeV/{{mvar|c}}.{{cite journal |last1=Connolly |first1=P.L. |last2=Hart |first2=E.L. |last3=Lai |first3=K.W. |last4=London |first4=G. |last5=Moneti |first5=G.C. |last6=Rau|first6=R. R.|last7=Samios|first7=N.P. |last8=Skillicorn |first8=I.O. |last9=Yamamoto |first9=S.S. |last10=Goldberg|first10=M. |last11=Gundzik |first11=M. |last12=Leitner |first12=J. |last13=Lichtman |first13=S. |display-authors=6 |date=15 April 1963 |title=Existence and properties of the {{Subatomic particle|Phi meson}} meson |journal=Physical Review Letters |volume=10 |issue=8 |pages=371–376 |doi=10.1103/PhysRevLett.10.371 |bibcode=1963PhRvL..10..371C|osti=12491318 |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.10.371 |access-date=5 May 2017 }}{{cite press release |title='K' for KLOE ... and 'Z' for Zweig |date=30 August 1999 |series=CERN Courier |url=http://cerncourier.com/cws/article/cern/28072 |via=cerncourier.com |access-date=6 May 2017}} In essence, the reaction involved a beam of {{SubatomicParticle|Kaon-}}s being accelerated to high energies to collide with protons.

The {{Subatomic particle|Phi meson}} meson has several possible decay modes. The most energetically favored mode involves the {{Subatomic particle|Phi meson}} meson decaying into three pions, which is what would naïvely be expected. However, we instead observe that it decays most frequently into two kaons.{{cite book |last=Griffiths |first=David |year=2008 |title=Introduction to Elementary Particles |edition=2nd rev. |publisher=Wiley-VCH |location=Weinheim, DE |isbn=978-3-527-40601-2 }} Between 1963 and 1966, three people, Susumu Okubo, George Zweig, and Jugoro Iizuka, each independently proposed a rule to account for the observed suppression of the three pion decay.{{cite journal |first=S. |last=Okubo |author-link=Susumu Okubo |year=1975 |title={{grey|[no title cited]}} |journal=Phys. Lett. |volume=5 |orig-year=1963 }}{{cite report |first=G. |last=Zweig |author-link=George Zweig |year=1964 |title={{grey|[no title cited]}} |series=CERN Report |id=8419/TH412 }}{{cite journal |first=J. |last=Iizuka |year=1966 |title={{grey|[no title cited]}} |journal=Prog. Theor. Phys. Suppl. |volume=37 |issue=21 }} This rule is now known as the OZI rule and is also the currently accepted explanation for the unusually long lifetimes of the {{Subatomic particle|link=yes|J/Psi}} and {{Subatomic particle|link=yes|Upsilon}} mesons. Namely, on average they last {{nobr| ~ 7 × {{10^|−21}} s }} and {{nobr| ~ 1.5 × {{10^|−20}} s }} respectively. This is compared to the normal mean lifetime of a meson decaying via the strong force, which is on the order of {{nobr| {{10^|−23}} s .}}

In 1999, a {{Subatomic particle|Phi meson}} factory named DAFNE (or DA{{Subatomic particle|Phi meson}}NE since the F stands for "{{Subatomic particle|Phi meson}} Factory") began operation to study the decay of the {{Subatomic particle|Phi meson}} meson in Frascati, Italy. It produces {{Subatomic particle|Phi meson}} mesons via electron-positron collisions. It has numerous detectors, including the KLOE detector which was in operation at the beginning of its operation.

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• List of particles
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Category:Mesons

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Category:Subatomic particles with spin 1