Review Article

Dark Matter: A Primer

Table 1

The particles predicted by the Standard Model. Approximate masses of particles as last reported by the Particle Data Group [30].
(a) Fermions

Generation 1Generation 2Generation 3
Particle Mass (MeV) Charge Particle Mass (MeV) Charge Particle Mass (MeV) Charge

up quark () 2.55 + charm quark () 1270 + top quark () 171200 +
down quark () 5.04 strange quark () 104 bottom quark () 4200
electron () 0.511−1 muon () 105.7−1 tau () 1776.8−1
neutrino () <2. 0 neutrino ()0.19 0 neutrino ()18.2 0

(b) Gauge Bosons

Particle Force Acts through Acts on Mass (MeV) Charge

Photon () Electromagnetic Electric charge Electrically charged particles <1 × 0
boson () Weak nuclear Weak interaction Quarks and leptons 91188 0
bosons () Weak nuclear Weak interaction Quarks and leptons 803981
Gluon () Strong nuclear Color charge Quarks and gluons 0 0
Higgs boson () Higgs force Higgs field Massive particles114400 0