2. Particle Physics "three quarks for Muster Mark" -James Joyce (Finnegan’s Wake) Contents: Particle Accelerators Quantum Electrodynamics and Feynman diagrams The Yukawa Particle Particles and Antiparticles Conservation Laws Types of Particles Strange Things and Quark Theory

3. Particle Accelerators TOC Basic concept - Vq = 1 / 2 mv 2 Provide energy for nuclear reactions Create particles from energy Proton Source Vacuum Beam Steering (RevereWare) Experiments +150,000 V

4. Particle Accelerators TOC SLAC - electron accelerator Potential switches 50 GeV - mass?

5. Particle Accelerators TOC Cyclotrons - In a magnetic field to curve path Potential switches Mass dilates as v->c Synchrotrons - Fermilab(1.0 km), CERN (8.5 km)

6. 8.5 km in diameter

8. Quantum Electrodynamics TOC Coulomb’s law - Force fields Richard Feynman - EM forces are mediated by photons: Richard Feynman 1918-1988 Feynman Diagram Virtual photons:  E  t > h / 2  (Exist for so short a time - never detected)

9. The Yukawa Particle TOC Photons mediate the EM force Yukawa proposes a particle to mediate strong nuclear force Hideki Yukawa 1907-1981 He names it the meson - (between electron and proton)  E  t =  E( d / c ) = h / 2   E = hc / 2  d = 130 MeV

10. The Yukawa Particle TOC Hideki Yukawa 1907-1981 Muon discovered in cosmic radiation m = 106 MeV - doesn’t interact The pi meson (pion) is discovered in 1947 in cosmic rays (3 charge states):  + - 139.6 MeV/c 2  o - 135.0 MeV/c 2  - - 139.6 MeV/c 2 p + p --> p + p +  o p + p --> p + n +  + (conservation of charge)

11. The Four Forces of Nature TOC Type Strong Nuclear Electromagnetic Weak Nuclear Gravitational Relative Strength 1 10 -2 10 -6 10 -38 Field Particle Gluons (mesons) Photon W + and Z o Graviton?

12. Particles and Antiparticles TOC NameParticleAntiparticle Electrone - e + p Protonpp Pion  +  - Some particles have no antiparticle + and - are electron charges When particle meets antiparticle - annihilation (rest mass + E k turns to energy or other particles)

13. Selected list (there are hundreds of hadrons) Self as antiparticle + and - are electron charges….

15. Conservation Laws - Baryon Number TOC Conservation of charge Conservation of mass/energy Conservation of nucleon.... In general, baryon number is conserved:

16. Conservation Laws - Baryon Number TOC In general, baryon number is conserved: This reaction can never happen: p + n -> p + p + p (Antiparticles have B = -1) Baryon numbers: 1 + 1  1 + 1+ -1

17. Conservation Laws - Baryon Number TOC Heavy baryons decay to lighter ones Proton is lightest - must be stable

18. Whiteboards: Conservation of Baryon Number 11 | 2 | 3 | 4234 TOC

19. W 0 What is the total Baryon number of p + n + n +  + 1 + 1 + -1 + -1 = 0

20. What is the total Baryon number of  + +  + +  o +  + -1 + -1 + 1 + 0 = -1 W

21. yes Can this reaction occur? p + p --->  - +  + 1 +-1 = 1 + -1 W

22. no Can this reaction occur? p + n --->  o +  + 1 +-1  -1 + -1 W

23. no Can this reaction occur?  o + n --->  o +  + B: 1 +-1 = 1 + -1 C: 0 + 0 != 0 + 1 W

24. Conservation Laws - Lepton Number TOC Lepton number is conserved too L e - Electron/electron neutrino L  - Muon/muon neutrino L  - Tau/Tau neutrino Remember - anti particles have negative lepton numbers Neutrinos are believed to have mass

25. Conservation Laws - Lepton Number TOC 60 27 Co 60 28 Ni +  - + e 13 7 N 13 6 C +  + + e Beta Decay: Emission of an electron neutrino allowed L e to be conserved: L e L  L  Electrone-+100 Neutrino (e) e +100 Muon  -0+10 Neutrino (  )  0+10 Tau  -00+1 Neutrino (  )  00+1

26. Whiteboards: Conservation of Lepton Number 11 | 2 | 3 | 4 | 52345 TOC

27. W dog biscuit Does this decay occur?  - ---> e - + e Charge is conserved L e : 0 = 1 + -1 L  : 1  0 + 0 L  is not conserved L e L  L  Electrone-+100 Neutrino (e) e +100 Muon  -0+10 Neutrino (  )  0+10 Tau  -00+1 Neutrino (  )  00+1

28. yo mama Does this decay occur?  - ---> e - + e +  Charge is conserved L e : 0 = 1 + -1 + 0 L  : 1 = 0 + 0 + 1 Yes it occurs W L e L  L  Electrone-+100 Neutrino (e) e +100 Muon  -0+10 Neutrino (  )  0+10 Tau  -00+1 Neutrino (  )  00+1

29. the red Does this decay occur?  - ---> e + e +  Charge is Not conserved L e : 0 = 1 + -1 + 0 L  : 1 = 0 + 0 + 1 Does not occur W L e L  L  Electrone-+100 Neutrino (e) e +100 Muon  -0+10 Neutrino (  )  0+10 Tau  -00+1 Neutrino (  )  00+1

30.  What is the missing decay product?  - --->  - +  + ??? W L e L  L  Electrone-+100 Neutrino (e) e +100 Muon  -0+10 Neutrino (  )  0+10 Tau  -00+1 Neutrino (  )  00+1 Q: -1=-1 +0 +? EL#: 0 = 0 + 0 +? ML#: 0= 1 + -1 +? TL#: 1 =0 + 0 +?

31. e+ What is the missing decay product?  + ---> ?? +  + e Q: +1=? +0 +0 EL#: 0 = ? + 0 +1 ML#: -1= ? + -1 +0 TL#: 0 =? + 0 +0 W L e L  L  Electrone-+100 Neutrino (e) e +100 Muon  -0+10 Neutrino (  )  0+10 Tau  -00+1 Neutrino (  )  00+1

32.  What is the missing decay product?  + --->  + + ?? +  W L e L  L  Electrone-+100 Neutrino (e) e +100 Muon  -0+10 Neutrino (  )  0+10 Tau  -00+1 Neutrino (  )  00+1 Q: +1=+1 +? +0 EL#: 0 = 0 + ? +0 ML#: 0= -1 + ? +0 TL#: -1 =0 + ? +-1

33. -- What is the missing particle? ?? ---> e- + e +  W L e L  L  Electrone-+100 Neutrino (e) e +100 Muon  -0+10 Neutrino (  )  0+10 Tau  -00+1 Neutrino (  )  00+1 Q: ?=-1 +0 +0 EL#: ? = +1 + -1 +0 ML#: ?= 0 + 0 ++1 TL#: ? =0 + 0 +0

34. Types of Particles TOC Gauge Bosons - carry the electro-weak force Leptons - interact via weak and EM (charged) force Hadrons - interact via strong nuclear force Mesons - B = 0 Baryons - B = 1, (-1)…

35. Quark Theory TOC 1960s - Only 4 Leptons, but Hundreds of Hadrons Leptons seemed elementary/small (<10 -18 m) Not all Hadrons could be elementary Murray Gell-Mann suggests that Hadrons are made from quarks.quarks "three quarks for Muster Mark" -James Joyce (Finnegan’s Wake)

36. Quark Theory TOC Murray Gell-Mann suggests that Hadrons are made from quarks.quarks

37. Quark Theory TOC Proton: +1 charge, B = 1 Neutron: 0 charge, B = 1 Pion + : +1 charge, B = 0 Pion-: -1 charge, B = 0 Kaon-: -1 charge, B = 0 Try making other Hadrons yourself

38. Truly Fundamental particles TOC Generally accepted fundamental particles Three generations Top quark = 200 GeV/c 2