1. 1 FK7003 Elementary Particle Physics David Milstead milstead@physto.se A4:1021 tel: 5537 8663/0768727608

2. 2 FK7003 Format ● 19 lecture sessions ● 2 räkneövningnar ● Homepage http://www.physto.se/~milstead/fk7003/course.html ● Course book  Particle Physics (Martin and Shaw,3 rd edition, Wiley) ● Earlier editions can be used – handouts to be provided where appropriate. ● Supplementary books which may be useful but which are not essential  Introduction to Elementary Particles (Griffiths, Wiley)  Subatomic Physics (Henley and Garcia, World Scientific)  Particles and Nuclei (Povh, Rith, Scholz and Zetsche, Springer)  Quarks and Leptons (Halzen and Martin, Wiley) ● Assessment  2 x inlämningsuppgifter  tenta

3. 3 FK7003 Lecture outline LectureTopicMartin and Shaw (2 nd edition) Martin and Shaw (3 rd edition) Extra info 1Antiparticles, Klein-Gordon and Dirac equations, Feynman diagrams, em and weak forces 11Handout 2Units, fundamental particles and forces, Charged leptons and neutrino oscillations 22Handout 3Quarks and hadrons, multiplets, resonances2,53 4Räkneövning 1 5Symmetries: Noether’s theorem, C, P and T45 6Symmetries: C, P, CP violation, CPT10 7Hadrons: isospin and symmetries56 8Hadrons: bound states, quarkonia66 9Quantum chromodynamics: asymptotic freedom, jets, elastic lepton-nucleon scattering 77 10Räkneövning 2 11Relativistic kinematics: four-vectors, cross section Appendix B Handouts 12Deep-inelastic lepton-nucleon scattering: quark parton model, structure functions, scaling violations, parton density functions 77Handouts 13Weak interaction: charged and neutral currents, Caibbo theory88 14Standard Model: renormalisation, Electroweak unification, Higgs99 15Beyond the Standard Model: hierarchy problems, dark matter, supersymmetry, grand unified theories 11 16Accelerators – synchrotron, cylcotron + LHC34Handouts 17Detectors: calorimeter, tracking, LHC detectors, particle interactions in matter 34Handouts 18Revision lecture 1 19Revision lecture 2

4. 4 FK7003 Particle physics is frontier research of fundamental importance.  particle physics research

5. 5 FK7003 The aim of this course ● Survey the elementary constituents in nature  Identification and classification of the fundamental particles  Theory of the forces which govern them over short distances ● Experimental techniques  Accelerator  Particle detectors

6. 6 FK7003 Lecture 1 Basic concepts Particles and antiparticles Klein-Gordon and Dirac equations Feynman diagrams Electromagnetic force Weak force

7. 7 FK7003 Going beyond the Schrödinger equation Classical mechanics Quantum mechanics (Schrödingers equation) Relativistic mechanics Quantum field theory (Dirac, Klein- Gordon equations, QED, weak, QCD) small fast

8. 8 FK7003 Implications of introducing special relativity

9. 9 FK7003 Negative energy states t x t x

10. 10 FK7003 What does a particle moving backwards in time look like ? The equation of motion of charge q moving backwards in time in a magnetic field is the same as the equation of motion of a particle with charge -q moving backwards in time.

11. 11 FK7003 Antiparticles Special relativity permits negative energy solutions and quantum mechanics demands we find a use for them. (1) The wave function of a particle with negative energy moving forwards in time is the same as the wave function of a particle with positive energy moving backwards in time. Ok, the negative energy solutions must be used but we can convert them to positive energy states if we reverse the direction of time when considering their interactions. (2) A particle with charge q moving backwards in time looks like a particle with charge –q moving forwards in time. General argument that a particle with negative energy and charge q behaves like a particle with positive energy and charge -q. We expect, for a given particle, to see the ”same particle” but with opposite charge: antiparticles. Antiparticles can be considered to be particles moving backwards in time - Feynman and Stueckelberg. Hole theory (not covered) provides an alternative, though more old fashioned way of thinking about antiparticles.

12. 12 FK7003 Electron and the positron 1897 e - discovered by J.J. Thompson 1932 Anderson measured the track of a cosmic ray particle in a magnetic field. Same mass as an electron but positive charge The positron ( e + ) - anti-particle of the electron Nobel prize 1936 Every particle has an antiparticle. Some particles, eg photon, are their own antiparticles. Special rules for writing particles and antiparticles, eg antiproton p, given in next lecture.

13. 13 FK7003 Klein-Gordon equation

14. 14 FK7003 The Dirac Equation

15. 15 FK7003 Implications of the Dirac Equation

16. 16 FK7003 How particles interact – exchange forces Electromagnetic force -- -- + -- + + - - - Repulsion Attraction photon Particles carrying charge interact via the exchange of photons (  ) mass= 0, spin= 1 (boson)

17. 17 FK7003 Electromagnetic processes

18. 18 FK7003 Feynman diagrams

19. 19 FK7003 (1) Electromagnetic processes t s vertex

20. 20 FK7003 (1) Basic electromagnetic diagrams t s ((g) and (h) become clear soon) vertex

21. 21 FK7003 (2) Is energy conservation violated ? t s tt real particle virtual particle (  )

22. 22 FK7003 (3) Using Feynman diagrams  Negative energy solutions –antiparticles. QM insists we use them!   

23. 23 FK7003 (3) Using Feynman diagrams    + 5 other contributions

24. 24 FK7003 Question

25. 25 FK7003 (3) Using Feynman diagrams e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- + + …. +

26. 26 FK7003 Question

27. 27 FK7003 Understanding forces

28. 28 FK7003 e-e- e-e- e-e- W-W- e e+e+ The weak force (neutrinos – next lecture) (  decay)

29. 29 FK7003 The fundamental forces Different exchange particles mediate the forces: strong electromagnetic weak InteractionRelative strength RangeExchangeMass (GeV) ChargeSpin Strong1Short (  fm) Gluon001 Electromagnetic1/137Long (1/r 2 ) Photon001 Weak10 -9 Short (  10 -3 fm) W + W -,Z80.4,80.4, 91.2 +e,-e,01 Gravitational10 -38 Long (1/r 2 ) Graviton ? 002 No quantum field theory yet for gravity

30. 30 FK7003 Summary  Antiparticles and spin states are predicted when when relativity and quantum mechanics meet up!  Antiparticles correspond to negative energy states moving backwards in time.  Feynman diagram formalism developed and used for (very basic) rate estimation  Generic approach for all forces  Weak force is weak because of the mass of the exchanged particles.