Option 212: UNIT 2 Elementary Particles Department of Physics and Astronomy REVISION LECTURE

ATOMIC SUBSTRUCTURE m

Crib sheet (or what you need to know to pass the exam) The zoo of particles and their properties –Leptons (e -,      e      –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=m 0 c 2 ), and the equations of conservation of relativistic energy and momentum, e.g. E 2 = p 2 c 2 + (m 0 c 2 ) 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 anti- quarks) 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 –( 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