Flashcard: Fundamentals of Particle Interactions — 24 carte

Flavour symmetry — meaning?

Approximate invariance treating quark flavours interchangeably.

Isospin SU(2) — quarks?

Groups up and down quarks into a doublet.

SU(3) flavour symmetry — role?

Organizes light quarks into multiplets, relates hadron properties.

Flavour multiplets — purpose?

Classify hadron states with related quantum numbers.

Refined flavour symmetry — focus?

Combines quark-flavour states into hadron wavefunctions.

QCD — what?

Quantum field theory of strong interactions via colour charge.

Local gauge invariance — requirement?

Physics unchanged under position-dependent gauge transformations.

Color SU(3) — symmetry?

Non-Abelian gauge symmetry governing quark transformations.

Gluon — what?

Gauge boson mediating the strong force, carries colour.

Non-Abelian gauge theory — feature?

Generators do not commute, gluons self-interact.

Colour confinement — phenomenon?

Coloured quarks/gluons cannot be isolated as free particles.

Asymptotic freedom — behaviour?

Weakens at high energies, allows perturbative QCD.

QCD in e+e− — role?

Produces hadrons via quark hadronization after annihilation.

Hadron collisions — model?

Parton model treats hadrons as quark/gluon constituents.

Colour factors — what?

Numerical weights from colour algebra affecting amplitudes.

Force carriers — gluons?

Gluons mediate strong interaction between coloured partons.

Weak charged current — effect?

Couples quarks/leptons, changes flavour via W exchange.

Coupling constant g — significance?

Sets interaction strength; amplitude scales with g².

W boson — what?

Mediator of charged-current weak interactions, changes flavour.

Chiral structure — describes?

Weak interactions couple differently to left/right-handed fermions.

Muon decay — arrow?

Arrow points to antiparticle: electron antineutrino.

Lepton universality — hypothesis?

Weak coupling is equal for all charged leptons.

Neutrino scattering — process?

Neutrinos transfer energy/momentum to matter.

Ionisation loss — at low v?

Largest, scales as 1/v².