Particles

From dankwiki
Revision as of 10:39, 17 July 2012 by Dank (talk | contribs) (Created page with "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 hadr...")
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

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.

Top quark

  • 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

Fermions

  • Half-integer spin, Fermi-Dirac statistics (Pauli Exclusion Principle)
  • All leptons
  • 3-quark hadrons (baryons)


Leptons

Fundamental (not made of quarks, pointlike) fermions.

Charged (Electron-like)

Massive.

  • Electron / positron
  • Muon / antimuon
  • Tau / antitau

Neutral (Neutrinos)

At least two of these are massive.

  • Neutrino / antineutrino
  • Tau n/an
  • Muon n/an

Bosons

  • Integer spin, Bose-Einstein statistics (no Pauli Exclusion Principle)
  • 2-quark hadrons (mesons)

Photon

W/Z Bosons

  • Mediators of the weak nuclear force

Gluons

Higgs Boson

Graviton (predicted)

Hadrons

  • 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)