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weak interactions

weak interactions. weak decays beta decay of neutron. n. p. problem energy and momentum not conserved. e. W. Pauli: 1930  Neutrino mass ~ m(e). weak decays beta decay of neutron. n. p. e. electron. p. n. antineutrino.

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weak interactions

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  1. weak interactions

  2. weakdecays betadecay of neutron

  3. n p problem energy and momentum not conserved e

  4. W. Pauli: 1930  Neutrino mass ~ m(e)

  5. weakdecays betadecay of neutron

  6. n p e

  7. electron p n antineutrino direct interaction of four fermions Enrico Fermi, ~1936

  8. Enrico Fermi

  9. weak interactions current-current interaction weak currents ~ lefthanded:

  10. lefthanded fermion S= - 1/2 righthanded antifermion S = + 1/2

  11. maximal breaking of parity

  12. weak interaction of the quarks beta – decay d  u

  13. weak decays of strange particles ( u d s ) ( u u d ) s  u

  14. Cabibbo angle:  flavor mixing

  15. 1957 weak bosons W J. Schwinger

  16. W

  17. - 1964 => 1968 gauge theory of the electroweak interactions ( Glashow, Salam, Weinberg )

  18. Glashow Salam Weinberg 1964-1968

  19. weak and electromagnetic interactions => electroweak interactions partial unification

  20. gaugegroup SU(2)xU(1)

  21. S U (2) xU (1) weak interaction electromagnetic interaction

  22. 4 gauge bosons W(+) W(-) Z photon

  23. SU(2)xU(1) weak Interactions W(+) – W(-) photon neutral current - Z

  24. photon: superposition SU(2)  U(1)

  25. Why photon massless? Why W–boson massive?

  26. mass generation by spontaneous symmetry breaking

  27. spontaneous symmetry breaking in classical mechanics rotation symmetry

  28. spontaneous symmetry breaking baki

  29. direction singled out rotation symmetry broken

  30. spontaneous symmetrrybreaking in fieldtheory

  31. Peter Higgs

  32. Kibble Guralnik Hagen Englert Brout

  33. example 1: real scalar field V potential

  34. self - interaction:

  35. => 2 groundstates

  36. example 2: complex scalar field

  37. 2

  38. spontaneous mass generation in gauge theories: U(1)

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