Fundamental Interactions and Particles

Real nuclear and particle physics for talented high schoolers.

Online from anywhere · or in-person in Princeton, NJ

A World Through the Lens of Fundamental Interactions

This course explores the building blocks of matter, one of the four Modern Physics electives in the Physics Lyceum: High School curriculum. It follows the Deep Physicsmodel that runs through the whole SoTS Physics Lyceum.

The course runs on theory, problem-solving sessions, and homework, building the modern particle concept from first principles.

1. Events, Spacetime, and Four-Momentum

What an experiment actually records, and the language for describing it. Scales from atoms to quarks. Rutherford scattering, resolution, and momentum transfer: why reaching a smaller structure costs more energy. Worldlines, light cones, and causality on spacetime diagrams. Proper time and time dilation, with the atmospheric muon as the evidence. Four-momentum and invariant mass, E² = p²c² + m²c⁴. Collisions, decays, and reaction thresholds.

2. States, Modes, and Quantum Fields

Where the modern idea of a particle comes from. A physical system, a degree of freedom, and the quantum state as the complete predictive information about it. Measurement and probability, with polarization and spin as the two-state prototypes. Coupled oscillators and normal modes, and a field as a system with many modes. The quantum oscillator: number states, the vacuum, and ladder operators. Quantizing field modes, and occupation numbers for bosons and fermions.

3. The Nucleus

The first many-body system where the quantum ideas have to work. Nuclear size and density, the nuclear force, the mass defect, and the curve of binding energy, set by the competition between strong attraction, Coulomb repulsion, and the Pauli principle. Liquid-drop and shell models. Magic numbers and the valley of stability. The decay law and the half-life. Alpha decay as tunnelling, and beta decay as the road to the neutrino. Q-values, cross sections, and resonances. Fission, chain reactions, fusion, and the energy of the stars.

4. Detectors, Accelerators, and Reconstruction

How a microscopic interaction becomes a macroscopic record. What a charged particle leaves behind in matter. Scintillators, semiconductor detectors, tracking, calorimetry, and Cherenkov radiation. Cyclotrons, synchrotrons, linacs, and colliders. Luminosity and event rate. Cosmic rays as a natural beam. Two-body decay kinematics, and reconstructing an invariant mass from the four-momenta of the daughters, which is how a state as short-lived as the J/ψ or the Z is found at all.

5. Quarks, Hadrons, and Symmetry

How particles are sorted, and what the sorting reveals. The historical zoo: the muon, the pion, the kaon, the strange particles, antiparticles. Mesons and baryons, flavour and colour, and the quark model. Deep-inelastic scattering, and the evidence that the proton has constituents. Parity, charge conjugation, time reversal, and CPT. The Wu experiment. Isospin and the internal symmetries, with a first look at U(1), SU(2), and SU(3), and why a conservation law is what a symmetry looks like from the outside.

6. The Standard Model and the Early Universe

The three interactions, and what they built. QED: scattering, annihilation, and pair production, with Feynman diagrams introduced as bookkeeping for transition amplitudes. QCD: colour, gluons, confinement, asymptotic freedom, jets, and hadronization. The weak interaction: the W and the Z, and parity violation. Neutrino oscillations, where the flavour states and the propagating states are simply not the same basis. The Higgs field, symmetry breaking, and where the masses come from. Nucleosynthesis, CP violation, dark matter, and the questions still open.

The specific topics, and the depth given to each, may shift depending on class priorities and the dynamics of the cohort.

How Particle Physics Is Taught in This Course

The course is built around one question: what do physicists actually mean by a particle?

Most introductory courses answer it with a tiny object that has a fixed list of properties. Students who continue in physics then spend years unlearning that picture. Here the answer is built in the right order instead: experiments and relativistic kinematics first, then quantum states and measurement, then classical modes and the quantum oscillator. Only then does a particle arrive as what it is in the theory, a one-quantum excitation of a field mode, and that idea carries the rest of the semester.

Core and enrichment. Every topic has a core path that the whole class follows, and optional further material for students who want to push harder. This ranges from fuller relativistic derivations to Fock-space notation and running coupling constants. A student can go as deep as they want without the class moving faster than the cohort.

Bonus assignment. Students who want to work with real collider data can reconstruct a resonance for themselves, calculating an invariant mass from the measured four-momenta of decay products in CERN open data and finding the peak. It is a bonus, not required coursework.

What this course does not cover. The Dirac equation, spinor calculus, gauge-field Lagrangians, and renormalization are out of scope by design. They are the next formal level, met in a quantum field theory course. What this course gives first is the physical content those methods encode.

Texts and Requirements

Texts. The course relies on several books rather than working through one. Bettini, Introduction to Elementary Particle Physics, and Basdevant, Rich and Spiro, Fundamentals in Nuclear Physics, carry the particle and nuclear spines. Tavernier and Braibant carry the experimental side, and Griffiths supplies the harder problems.

Prerequisites. Strong algebra, trigonometry, and vectors; comfort with scientific notation and reading graphs; and basic mechanics, electricity, and magnetism. Basic calculus is expected: the course uses it, and the Lyceum teaches physics rather than calculus, so a student needs to arrive with it. Neither Special Relativity nor Quantum Mechanics is required: the course builds the relativity and quantum-state language it needs in condensed form. Students who have taken either will recognize the opening weeks and go deeper in them.

Schedule, Tuition, and Enrollment

Schedule, tuition, and enrollment
13.6 TeV