Particle Physics and Fundamental Interactions
The Standard Model organizes matter particles and three quantum interactions; conservation laws determine which transformations are possible.
Learning goals
- classify quarks, leptons, hadrons and antiparticles;
- construct simple baryons and mesons from quarks;
- compare strong, electromagnetic, weak and gravitational interactions;
- apply charge, energy, momentum, baryon and lepton conservation;
- interpret collision evidence without treating diagrams as literal tracks.
1. Matter particles in the Standard Model
Fundamental spin-$1/2$ matter particles are fermions. Six quarks occur in three generations: up/down, charm/strange and top/bottom. Up-type quarks have electric charge $+2/3\,e$; down-type quarks have $-1/3\,e$. Six leptons are the electron, muon and tau, each paired with a neutrino. Charged leptons carry $-e$; neutrinos have zero electric charge and interact weakly. Ordinary stable matter mostly uses first-generation up and down quarks plus electrons.