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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