Particle physics and energy

The rest mass of the products = total energy before - the kinetic energy of the products

Hadrons and leptons

Hadrons

Hadrons are made from quarks

Hadrons

• Baryon (3 quarks/antiquarks)
• Meson (a quark/antiquark pair)

Protons and neutrons are baryons.

Proton = up, up, down

Neutron = up, down, down

Kaons and pions are mesons.

Kaons contain strange quarks, pions do not.

Kaon+ = anti-strange and up

pion+ = anti-down and up

Kaons and pions have different rest masses but the same charge.

A kaon has a greater rest mass than a muon.

Leptons

Leptons are fundamental particles.

They consist of electrons, neutrinos and muons.

Electrons and muons are charged and neutrinos are neutral.

Muons are unstable and quickly decay, they do not occur in nature.

Muons have a greater rest mass than electrons.

Conservation of baryon number

A quark has a baryon number of +1/3.

An antiquark has a baryon number of -1/3

In any production, annihilation or decay; baryon number is always conserved (including strange particles).

Baryons have a baryon number of +1

Anti-baryons have a baryon number of -1

Leptons have a baryon number of 0