Editing Meson (section)

==== Flavourless mesons ====
Flavourless mesons are mesons made of pair of quark and antiquarks of the same flavour (all their [[flavour quantum number]]s are zero: [[Strangeness|{{mvar|S}}]] = 0, [[Charm (quantum number)|{{mvar|C}}]] = 0, [[Bottomness|{{mvar|{{prime|B}}}}]] = 0, [[Topness|{{mvar|T}}]]  = 0).{{efn|group=lower-roman|For the purpose of nomenclature, the isospin projection {{mvar|I}}{{sub|3}} is treated as if it were ''not'' a flavour quantum number. This means that the charged pion-like mesons ({{mvar|π}}{{sup|±}}, {{mvar|a}}{{sup|±}}, {{mvar|b}}{{sup|±}}, and {{mvar|ρ}}{{sup|±}} mesons) follow the rules of flavourless mesons, even if they aren't truly "flavourless".}} The rules for flavourless mesons are:<ref name=PDGMesonsymbols/>
{|class="wikitable" style="text-align:center;margin:1em auto;"
|+ Nomenclature of flavourless mesons
|-
! rowspan=2 | {{SubatomicParticle|quark}}{{SubatomicParticle|antiquark}} content
! rowspan=2 |  [[Isospin|{{mvar|I}}]] 
! colspan=4 | [[Total angular momentum|{{mvar|J}}]]{{sup|[[Parity (physics)|{{math|P}}]][[C-parity|{{math|C}}]]&nbsp;{{efn|group=lower-roman|name=Cparity| [[C-parity]] is only relevant for neutral mesons.}} }}
|-
! 0<sup>−+</sup>, 2<sup>−+</sup>, 4<sup>−+</sup>, ...
! 1<sup>+−</sup>, 3<sup>+−</sup>, 5<sup>+−</sup>, ...
! 1<sup>−−</sup>, 2<sup>−−</sup>, 3<sup>−−</sup>, ...
! 0<sup>++</sup>, 1<sup>++</sup>, 2<sup>++</sup>, ...
|-
|{{SubatomicParticle|up quark}}{{SubatomicParticle|down antiquark}}<br/><math>\mathrm{\tfrac{u\bar{u} - d\bar{d}}{\sqrt{2}}}</math><br/>{{SubatomicParticle|down quark}}{{SubatomicParticle|up antiquark}} || 1 || {{SubatomicParticle|link=yes|pion+}}<br/>{{SubatomicParticle|link=yes|pion0}}<br/>{{SubatomicParticle|link=yes|pion-}} || b<sup>+</sup><br/>b<sup>0</sup><br>b<sup>−</sup> || {{SubatomicParticle|link=yes|rho+}}<br>{{SubatomicParticle|link=yes|rho0}}<br/>{{SubatomicParticle|link=yes|rho-}} || a<sup>+</sup><br/>a<sup>0</sup><br/>a<sup>−</sup>
|-
|Mix of <br/>{{SubatomicParticle|up quark}}{{SubatomicParticle|up antiquark}}, {{SubatomicParticle|down quark}}{{SubatomicParticle|down antiquark}}, {{SubatomicParticle|strange quark}}{{SubatomicParticle|strange antiquark}} || 0 || {{SubatomicParticle|link=yes|Eta}}<br>{{SubatomicParticle|link=yes|Eta prime}} || h<br/>{{prime|h}} || {{SubatomicParticle|link=yes|omega meson}}<br/>{{SubatomicParticle|link=yes|phi meson}} || f<br/>{{prime|f}}
|-
|{{SubatomicParticle|Charm quark}}{{SubatomicParticle|Charm antiquark}} || 0 || {{SubatomicParticle|link=yes|Charmed Eta}} || h<sub>c</sub> || ψ{{efn|group=lower-roman|name=JPsi| For the special case {{mvar|J}}{{sup|{{math|PC}}}}{{=}}1{{sup|−−}}, the ψ is called the {{SubatomicParticle|link=yes|J/Psi}} }} || χ<sub>c</sub>
|-
|{{SubatomicParticle|Bottom quark}}{{SubatomicParticle|Bottom antiquark}} || 0 || {{SubatomicParticle|link=yes|Bottom Eta}} || h<sub>b</sub> || {{SubatomicParticle|link=yes|Upsilon}} || χ<sub>b</sub>
|-
|{{SubatomicParticle|Top quark}}{{SubatomicParticle|Top antiquark}} || 0 || {{SubatomicParticle|link=yes|Top Eta}} || h<sub>t</sub> || {{SubatomicParticle|link=yes|Theta meson}} || χ<sub>t</sub>
|}

{{reflist|group=lower-roman}}

;In addition:
* When the [[Meson spectroscopy|spectroscopic state]] of the meson is known, it is added in parentheses.
* When the spectroscopic state is unknown, mass (in [[Electronvolt#Mass|MeV/''c''<sup>2</sup>]]) is added in parentheses.
* When the meson is in its [[ground state]], nothing is added in parentheses.