Particle Type Quark
Composition
Rest Mass
in MeV
  ?        Pion (neutral)
Pion (+ charge)
Pion (- charge)
(uu - dd)  / 2
ud
du
135.0
139.6
139.6
Rho (neutral)
?    Rho (+ charge)
Rho (- charge)
(uu - dd)  / 2
ud
du
775.5
775.4
775.4
Omega (v) (uu + dd)  / 2 782.7
Phi  (f) ss 1,020.0
D Meson

Ds Meson
cd
cu
cs
1,869.4
1,864.6
1,969.0
Psi (J/Y) cc 3,096.9
B (+ve)
B (neutral)
B (strange)
B (charmed)
ub
db
sb
cb
5,279.2
5,279.5
5,366.3
6,276.0
?                 Upsilon bb 9,460.4
Mesons are unstable particles comprising a quark/antiquark pair, either of the same or different flavors.  The table to the left shows some of the Mesons identified so far, their quark composition and approximate rest mass.  Note the massive Upsilon particle that has a mass more than ten times that of the Proton.  It is also interesting to refer to the estimated quark masses, and look at the correlation between those masses and the masses given in the Standard Model section.  It is clear that in many particles, most of the mass derives not from the component quarks themselves, but from the mass equivalent of the energy derived from quark kinetic energy and from gluon energy. 

Having integer spin, mesons are classed as bosons.  This means that they can act as force mediating particles over short distances, and participate in processes such as the nuclear interaction.  Mesons participate in both the weak and strong nuclear interactions, and charged Mesons participate in the electromagnetic interaction.  Mesons are intrinsically unstable, but generally the more massive the particle, the more unstable it is.  Mesons have been instrumental in many quark experiments; for example, the charm quark was first seen in the Psi meson in 1974, and the bottom quark in the upsilon meson in 1977.

Each meson has a corresponding antiparticle (antimeson) where quarks are replaced by their corresponding antiquarks and vice-versa.  There is a list of the different Mesons on the Wikipedia website that is kept fairly up to date. 
1st Generation 2nd Generation 3rd Generation
"Up"
Type Quarks
Up Quark
Mass:   1.87-2.15 MeV
Charge:
2/3
Spin:    
1/2
ID:            u, u
Charm Quark
Mass:   1.18-1.34 GeV
Charge:
2/3
Spin:    
1/2
ID:            c, c
Top Quark
Mass:  172.6-173.6 GeV
Charge:
2/3
Spin:    
1/2
ID:            t, t
"Down" Type Quarks
Down Quark
Mass:    4.63-4.95 MeV
Charge:
-1/3
Spin:    
1/2
ID:            d, d
Strange Quark
Mass:    90-100 MeV
Charge:
-1/3
Spin:    
1/2
ID:            s, s
Bottom Quark
Mass:    4.2 or 4.68 GeV
Charge:
-1/3
Spin:    
1/2
ID:            b, b
Quark Summary                   (compiled from a number of different sources)

Mesons

Physics

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Composite Particles
WILLIAM & DEBORAH HILLYARD
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