Theta meson

Not to be confused with the θ⁺ of the τ–θ puzzle, which is now identified as kaon, or with the Θ⁺ and Θ⁺
_c, formerly thought to be pentaquarks.

The theta meson (θ)^[1] is a hypothetical form of quarkonium (i.e. a flavourless meson) formed by a top quark (t) and top antiquark (t). As a P-odd and C-odd tt state, it is analogous to the ϕ (ss), J/ψ (cc) and ϒ (bb) mesons. Due to the top quark's short lifetime, the theta meson is expected to not be observed in nature.^[2]

Theta meson

Quark structure of the theta meson
Composition	tt
Statistics	bosonic
Interactions	strong, weak, gravitational, electromagnetic
Status	hypothetical
Antiparticle	self
Electric charge	0 e
Isospin	0
Hypercharge	0
Parity	−1
C parity	−1

See also

• List of mesons