PX386 Nuclear and Particle Physics

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PX386 Nuclear and Particle Physics
UNIVERSITY OF WARWICK DEPARTMENT OF PHYSICS
Lecture on the Web http//www2.warwick.ac.uk/fac
/sci/physics/teach/module_home/px386/
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Leptons
2.2
0.19
18.2
Conserved quantum numbers Lepton number Le, Lm,
Lt
Example
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Quark Jet Example
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Quark Jet Example
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More Quantum Numbers
Baryon Number, Parity, Quark Flavour and Isospin
Zoology of Hadrons (incomplete list)
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Hadrons

• Quarks form Hadrons
• No isolated Quarks
• only bound systems of
• several quarks known
• Quark Model brings
• order into the Zoo
• Quantum numbers to
• order here Isospin and
• Quark Flavour Strangeness

Mesons qq
Baryon- number0
Baryons qqq
Baryon- number1
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Conservation Laws (1)

• Energy/Momentum is conserved
• Charge is conserved
• Spin is conserved
• Baryon Number is conserved
• Lepton Number is conserved
• CPT is conserved (Charge conjugation, Parity and
  Time reversal combined)

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Conservation Laws (2)

• Electromagnetism and Strong Force conserve these
  quantities.
• Parity
• Quark flavor (e.g. strangeness)
• Isospin (strong force only)
• The Weak Interaction violates these conservation
  laws
• Change neutron to proton change Isospin
• S-Quark can decay to u-Quark (and ?Q1 !)