For reasons that are not
understood, in addition to charge, processes conserve baryon
numberB and lepton numberL.
These quantities can't be conserved exactly or baryons and
leptons could not exist!
Particles and antiparticles
are created in matched pairs and destroyed in matched pairs.
Antiparticles have opposite charge, and opposite baryon or
lepton number, but the same mass.
So what's the antiparticle to the
photon, γ? If a particle does not have any intrinsic quantum
numbers associated with it, there is no way to tell the
difference between particles and antiparticles, so we say the
photon is its own antiparticle!
THE STANDARD MODEL OF
PARTICLES AND FORCES!
Quarks have flavor (u, d, c, etc.) and color
(r, g, b). Gluons carry a color and an anti-color, for 8
varieties in all.
In relativistic quantum physics,
antiparticles can be described as particles propagating backward
in time.
