Quarks: Spin of 1/2, Charge of +-1/3, +-2/3. Quarks experience all four fundamental interactions. By virtue of the strong interaction mediated by gluons (QCD), quarks are hadronized -- confined to hadrons. Within hadrons, they enjoy asymptotic freedom.
- 175GeV, +2/3. EXCEPT the top quark, whose lifetime is too short to be mediated by gluons, and is thus always observed bare
Strong nuclear force
- Repulsive at small distances (~.7fm), attractive at larger distances (through 2.5fm), falls off to 0
- This repulsion gives nucleons their "size"
- Mediated by gluons between quarks.
- Holds quarks together in hadrons, nucleons together in nucleus.
- Other quarks are only oberved confined
- Their presence is indicated by deep inelastic scattering experiments
- Color is white, charge is not
- Half-integer spin, Fermi-Dirac statistics (Pauli Exclusion Principle)
- All leptons
- 3-quark hadrons (baryons)
Fundamental (not made of quarks, pointlike) fermions.
- Electron / positron
- Muon / antimuon
- Tau / antitau
At least two of these are massive.
- Neutrino / antineutrino
- Tau n/an
- Muon n/an
- Integer spin, Bose-Einstein statistics (no Pauli Exclusion Principle)
- 2-quark hadrons (mesons)
- Mediators of the weak nuclear force
- Color confinement: hadrons must be "white"
- Quark of a color with anti-quark of the other color
- Three quarks (or antiquarks) of different colors
- Made of quarks, held together by strong force mediated by gluons
- Mesons: Bosons (one quark + one antiquark -> integer spin)
- Baryons: Fermions (three quarks -> half-integer spin)