omega meson

{{Short description|Meson that is a superposition of an up quark–antiquark and a down quark–antiquark pair}}

{{Infobox particle

| name = Omega meson

| image =

| caption =

| num_types = 1

| composition = $\approx \frac{u\bar{u}+d\bar{d}}{\sqrt{2}}$

| statistics = Bosonic

| group = Mesons

| interaction = Strong, weak, electromagnetic, gravity

| antiparticle = Self

| status =

| theorized = Yoichiro Nambu{{cite journal|title=Possible Existence of a Heavy Neutral Meson|first=Yoichiro|last=Nambu|journal=Physical Review|volume=106|issue=6|pages=1366–1367|date=April 25, 1957|doi=10.1103/PhysRev.106.1366|bibcode=1957PhRv..106.1366N}} (1957)

| discovered = Lawrence Berkeley National Laboratory (1961){{cite journal|doi=10.1103/physrevlett.7.178|title=Evidence for a T=0 three-pion resonance|first1=B. C.|last1=Maglić|first2=L. W.|last2=Alvarez|first3=A. H.|last3=Rosenfeld|first4=M. L.|last4=Stevenson|journal=Physical Review Letters|volume=7|issue=5|pages=178–182|date=August 14, 1961|bibcode = 1961PhRvL...7..178M| s2cid=121570977 }}{{cite journal|url=https://inspirehep.net/files/bed57fc443ad4a089648fd0574f4d256|title=Discovery of omega meson-first neutral vector meson: one researcher's personal account - Discovery story|date=1976|first=B.|last=Maglich|journal=Advanced Experimental Physics|volume=5|pages=79–105}}

| symbol = {{Subatomic particle|Omega meson}}

| mass = {{val|782.66|0.13|ul=MeV/c2}}

| mean_lifetime = {{val|7.58|0.11|e=-23|u=s}}

| decay_particle = {{Subatomic particle|Pion+|link=yes}}+{{Subatomic particle|Pion0|link=yes}}+{{Subatomic particle|Pion-|link=yes}} or {{Subatomic particle|Pion0|link=yes}}+{{Subatomic particle|Gamma|link=yes}}

| electric_charge = 0 e

| spin = 1

| strangeness =

| charm =

| bottomness =

| topness =

| isospin = 0

| hypercharge = 0

| parity = −1

| c_parity = −1

}}

The omega meson ({{Subatomic particle|Omega meson}}) is a flavourless meson formed from a superposition of an up quark–antiquark and a down quark–antiquark pair. It is part of the vector meson nonet{{cite tech report |last=Gell-Mann |first=M. |author-link=Murray Gell-Mann |date=March 15, 1961 |title=The Eightfold Way: A Theory of Strong Interaction Symmetry |publisher=California Inst. of Tech., Synchrotron Laboratory |location=Pasadena, CA |doi=10.2172/4008239 |number=TID-12608 |url=https://www.osti.gov/scitech/servlets/purl/4008239 |pages=24}}{{cite journal |last=Ne'eman |first=Y. |author-link=Yuval Ne'eman |date=August 1961 |title=Derivation of Strong Interactions from a Gauge Invariance |journal=Nuclear Physics |publisher=North-Ho lland Publishing Co. |location=Amsterdam |doi=10.1016/0029-5582(61)90134-1 |volume=26 |issue=2 |pages=222–229 |bibcode=1961NucPh..26..222N}} and mediates the nuclear force along with pions and rho mesons.

Properties

The most common decay mode for the ω meson is {{Subatomic particle|Pion+|link=yes}}{{Subatomic particle|Pion0|link=yes}}{{Subatomic particle|Pion-|link=yes}} at 89.2±0.7%, followed by {{Subatomic particle|Pion0|link=yes}}{{Subatomic particle|Gamma|link=yes}} at 8.34±0.26%.

class="wikitable"

! class=unsortable|Particle name

! Particle
symbol

! Antiparticle
symbol

! class=unsortable|Quark
content

! Rest mass (MeV/c²)

! width="50"|I^G

! width="50"|J^PC

! width="50"|S

! width="50"|C

! width="50"|B'

! Mean lifetime (s)

! class=unsortable|Commonly decays to

(>5% of decays)

Omega meson{{cite web|url=https://pdg.lbl.gov/2021/listings/rpp2021-list-omega-782.pdf|title=Particle listing - ω(782)|first=P. A.|last=Zyla|orig-year=2020|year=2021|publisher=Particle Data Group|access-date=June 9, 2021}}

|align="center"| {{Subatomic particle|Omega meson}}(782)

|align="center"| Self

|align="center"| $\frac{u\bar{u}+d\bar{d}}{\sqrt{2}}$

|align="center"| 782.66 ± 0.13

|align="center"| 0⁻

|align="center"| 1⁻⁻

|align="center"| 0

|align="center"| {{val|7.58|0.11|e=-23|u=s}}

|align="center"| {{Subatomic particle|Pion+|link=yes}}+{{Subatomic particle|Pion0|link=yes}}+{{Subatomic particle|Pion-|link=yes}} or
{{Subatomic particle|Pion0|link=yes}}+{{Subatomic particle|Gamma|link=yes}}

The quark composition of the {{Subatomic particle|Omega meson}} meson can be thought of as a mix between {{Subatomic particle|link=yes|up quark}}{{Subatomic particle|link=yes|up antiquark}}, {{Subatomic particle|link=yes|down quark}}{{Subatomic particle|link=yes|down antiquark}} and {{Subatomic particle|strange quark|link=yes}}{{Subatomic particle|strange antiquark|link=yes}} states, but it is very nearly a pure symmetric {{Subatomic particle|up quark}}{{Subatomic particle|up antiquark}}-{{Subatomic particle|down quark}}{{Subatomic particle|down antiquark}} state. This can be shown by deconstructing the wave function of the {{Subatomic particle|Omega meson}} into its component parts. We see that the {{Subatomic particle|Omega meson}} and {{Subatomic particle|Phi meson}} mesons are mixtures of the SU(3) wave functions as follows.{{cite web|last1=Amsler|first1=C.|last2=DeGrand|first2=T.|last3=Krusche|first3=B.|title=15. Quark Model|url=https://pdg.lbl.gov/2021/reviews/rpp2020-rev-quark-model.pdf|date=August 2019|access-date=9 June 2021|publisher=Particle Data Group}}

: $\omega = \psi_8 \sin\theta + \psi_1 \cos\theta$ ,

: $\phi = \psi_8 \cos\theta - \psi_1 \sin\theta$ ,

where

: $\theta$ is the nonet mixing angle,

: $\psi_1 = \frac{u\overline{u} + d\overline{d} + s\overline{s}}{\sqrt{3}}$ and

: $\psi_8 = \frac{u\overline{u} + d\overline{d} - 2s\overline{s}}{\sqrt{6}}$ .

The mixing angle at which the components decouple completely can be calculated to be $\arctan\frac{1}{\sqrt{2}}\approx35.3^\circ$ , which almost corresponds to the actual value calculated from the masses of 35°. Therefore, the {{Subatomic particle|Omega meson}} meson is nearly a pure symmetric {{Subatomic particle|up quark}}{{Subatomic particle|up antiquark}}-{{Subatomic particle|down quark}}{{Subatomic particle|down antiquark}} state.

References

Category:Mesons

Category:Onia

Category:Subatomic particles with spin 1

omega meson

Properties

See also

References