Encyclopedia of Chemistry

This is a list of mesons. This list is not comprehensive; it is a stub.

Particle	Symbol	Anti- particle	Quark Makeup	Spin and parity	Rest mass MeV/c²	S	C	B	Mean lifetime s	Principal decays	Notes
Charged Pion	π +	π −		Pseudoscalar	139.6	0	0	0	2.60×10-8	μ+ + νμ
Neutral Pion	π0	Self		Pseudoscalar	135.0	0	0	0	0.84×10-16	2γ	Makeup inexact due to non-zero quark masses
Charged Kaon	K +	K −		Pseudoscalar	493.7	+1	0	0	1.24×10-8	μ + νμ or π+ + π0
Neutral Kaon	K0			Pseudoscalar	497.7	+1	0	0	weak decay		Strong eigenstate - no definite lifetime (see kaon notes below)
K-Short				Pseudoscalar	497.7	(*)	0	0	0.89×10-10	π+ + π- or 2π0	Weak eigenstate - makeup is missing small CP-violating term (see kaon notes below)
K-Long				Pseudoscalar	497.7	(*)	0	0	5.2×10-8	π+ + e- + νe	Weak eigenstate - makeup is missing small CP-violating term (see kaon notes below)
Eta	η	Self		Pseudoscalar	547.8	0	0	0	5×10-19		Makeup inexact due to non-zero quark masses
Eta Prime	η'	Self		Pseudoscalar	957.6	0	0	0	3×10-21		Makeup inexact due to non-zero quark masses
Rho	ρ +	ρ −		Vector	776	0	0	0	0.4×10-23
Phi	φ	Self		Vector	1020	0	0	0	16×10-23
D	D +	D −		Pseudoscalar	1869	0	+1	0	10.6×10-13
D	D0			Pseudoscalar	1865	0	+1	0	4.1×10-13
Ds				Pseudoscalar	1968	+1	+1	0	4.9×10-13
J/Psi	J / ψ	Self		Vector	3096.9	0	0	0	7.2×10-21	e+ + e- or μ+ + μ- ...	See charmonium
B	B +	B −		Pseudoscalar	5279	0	0	+1	1.7×10-12
B	B0			Pseudoscalar	5279	0	0	+1	1.5×10-12
Bs				Pseudoscalar	5369	-1	0	+1	1.46×10-12
Bc				Pseudoscalar	6400	0	+1	+1	5×10-13
Upsilon		Self		Vector	9460	0	0	0	1.3×10-20	e+ + e- or μ+ + μ- ...	See bottomonium

Notes on neutral kaons

There are two complications with neutral kaons:

1. Due to neutral kaon mixing, the and are not eigenstates of strangeness. However, they are eigenstates of the weak force, which determines how they decay, so these are the particles with definite lifetime.
2. Furthermore, the linear combinations given in the table for the and are not exactly correct, since there is a small correction due to CP violation. See CP violation in kaons.

Note that these issues also exist in principle for other neutral flavored mesons; however, the weak eigenstates are considered separate particles only for kaons because of their dramatically different lifetimes.

See also

• List of baryons

References

• Griffiths, David J. (1998). Introduction to Electrodynamics (3rd ed.). Prentice Hall. ISBN 0-13-805326-X.