Department of Physics and Astronomy Option 212: UNIT 2 Elementary Particles REVISION LECTURE ATOMIC SUBSTRUCTURE 10-18 m Crib sheet (or what you need to know to pass the exam) • The zoo of particles and their properties – – – – Leptons (e-, m-, t-, ne , nm, nt) Hadrons (baryons and mesons) Their anti-particles The conservation laws and how to apply them (energy, momentum, baryon number, lepton numbers, strangeness, charge) Crib sheet (or what you need to know to pass the exam) • Quarks and their properties – Flavours: up, down, strange, charm, top ,bottom – How to combine quarks to form baryons and mesons • For example know that proton is uud, neutron is ddu, meson is quark-antiquark – Quark spin and color – Know about the eight-fold way patterns (but not expected to recall them!) Crib sheet (or what you need to know to pass the exam) • Fundamental forces and field particles • The standard model • And from special relativity, it’s important to understand the concepts of rest mass and energy (E=m0c2), and the equations of conservation of relativistic energy and momentum, e.g. E2 = p2c2 + (m0c2)2 Conservation laws, and particle properties: what I expect you to know (and what I don’t expect you to know) • Which particles are baryons, which are mesons, and which are leptons and hence when to apply the laws of baryon and lepton number conservation • The charges of baryons and leptons (easy, eg e+ p-) • That leptons have spin 1/2, baryons spin n/2 and mesons spin 0 or 1 – Focus on the most common hadrons: protons, neutrons, and pions • Which baryons are strange • I don’t expect you to remember their masses (ie for energy conservation). If required, these are on the Physical Constants sheet or will be given Quark properties: what you should know (and what you don’t need to remember) • Their general properties (ie that they have ‘spin’, ‘charge’, ‘baryon number’, and flavours like ‘strangeness’, ‘charm’, etc) • That they have baryon number 1/3 (-1/3 for antiquarks) • That they all have magnitude of spin = 1/2 • Strange quarks have strangeness = -1 • Quark charge (up = +2/3, down & strange = -1/3) • Know that proton is uud, neutron is ddu, meson is quark-antiquark Crib sheet (or what you need to know to pass the exam) • Re-read the chapter and my lecture notes – (www.star.le.ac.uk/~mbu) • Go back through the seminar, workshop and multiple choice questions • Also revise some of the examples done in the lecture • Practise more questions from Tipler • Do the past papers