Parity Violation: The Biggest Scientific Blunder of the 20th Century?

1. Parity Violation: The Biggest Scientific Blunder of the 20th Century? Dr Mark Hadley

2. Is Nature Symmetrical? We thought so until 1956 !! • A Major change in our view of space and time • Round Earth • Heliocentric view of Universe • Special Relativity (time is not absolute) • General relativity (spacetime is curved) • Big bang – Universe finite in space and time • Expanding Universe (time asymmetry)

3. Plan • Parity violation – the conventional view • My interest • Review of Parity conservation • Mechanics • Electromagnetism • Weak Interactions • An alternative view • Parity is Conserved !!

4. Space Inversion Inversion = reflection + 180° rotation Axial or Pseudo vector

5. Before After Effect of Parity - momentum The Parity Operator gives the transformation due an inversion of the spatial coordinates

6. Before After Effect of Parity - spin

7. Physical Review October 1956 p254-258 Parity violation in the weak interactions Tsung Dao Lee Chen Ning Yang

8. Look for an asymmetric outcome Start with a symmetrical state e- θ 60Ni + e- +υe 60Co I(θ)dθ = k (1 + αcosθ )sinθdθ

9. Experimentalists Wu   Ambler   Hayward  Hoppes  Hudson National Bureau of Standards USA 1956

10. actual result I(θ)dθ = k (1 –v/c cosθ )sinθdθ

11. Nobel prize winners 1957 Parity violation in the weak interactions Tsung Dao Lee Chen Ning Yang

12. But not quite so simple……. Is the initial state symmetrical? “We see from this analysis that the logical path from the observed asymmetry to the inferred nonconservation of parity in β decay is considerably more complex than the popular presentations would indicate.” L. E. Ballentine:

13. A gravitational explanation for quantum theory • Aims to explain • QM • Particle spectrum • Fundamental interactions • Predictions • No graviton (Gravity waves are just classical waves) • Spin-half • Parity is conserved

14. Parity is violated - FACT The Nobel Prize Committee say so. All the books say so.

15. Doh !

16. Explanations using GR • Boundary Conditions • Common source  

17. Doh!! Doh !!

18. Where have they gone wrong? • Exactly what has been observed? • Exactly what has been violated? • What, exactly, is the definition of Parity?

19. Parity in Newtonian Mechanics Parity conserved Before After  F = ma E = ½m v2 F = m(-a) -F = m (-a) -F = (-m)(-a) F = (-m)(-a) (± )E = ½(± m) v2   

20. Parity in Newtonian Mechanics P operator is chosen: • For simplicity • To conserve parity • Supported by: Special Relativity: (t-component of the energy momentum 4-vector) General Relativity:

21. e- e- e- e- e- Parity in electromagnetism Start with a symmetrical state…… e- Magnetic field pointing out

22. Parity in Electromagnetism Parity conserved Before After  F = q(E + v x B) Note: -F = q(-E + -v x (-B)) -F = q(-E + -v x B) -F = -q(E + -v x B) -F = -q(E + -v x (-B))   

23. Parity on magnetic poles

24. e- e- e- e- Parity in electromagnetism e- Magnetic field pointing out

25. e- e- e- e- e- Magnetic field pointing in

26. Duality Transforamtion • The roles of E and B can be reversed by a duality transformation:

27. In this order Parity in Electromagnetism P operator is chosen: • To conserve parity • For simplicity • Supported by the covariant formulation:

28. Effect of Parity The Parity Operator gives the transformation due an inversion of the spatial coordinates. We do not have a free choice of P operator. What are the transformations in beta decay?

29. “We see from this analysis that the logical path from the observed asymmetry to the inferred nonconservation of parity in β decay is considerably more complex than the popular presentations would indicate.” L. E. Ballentine: The assumption that the Cobalt nucleous is symmetrical is not only non-trivial - it may well be wrong !

30. e- e+ Anti 60Co What is the mirror image of a Cobalt atom? 60Co 60Co e- (not to scale)

31. Parity • Reverses • Momentum • Lepton number etc. • Charge • Unchanged • Spin • Is conserved

32. Conclusions • Space Inversion is a symmetry of Nature • Parity is conserved • The conventional P operator is not conserved.

33. Just a change of convention? • The conventional P operator may be combined with another transformation of degenerate multiplets. (eg particle anti-particle, neutrino flavours) • Impacts on unifying theories. “Not merely a matter of convention: on other particles P could have the usual effect.” Weinberg

34. Parity violation How could they get it so wrong?

35. How could they get it so wrong? • The Parity operation was defined before the experiments were done. • Particles were defined as eigenstates of Parity. • Simplicity of the operator took precendence over conservation - even though QFT required particles and antiparticles to be combined in the same equations. • There was no higher theory to appeal to. Watch this space!

36. Parity isConserved

37. Eigenvectors of P, H,J3 with eigenvalues 0,M,σ Parity Lorentz Boost

38. CP violation • Boundary conditions • Matter dominated Universe • T asymmetry (CPT theorem) • Expanding Universe • Parity = CP for some particles only! • More complicated effects of P on other degeneracies.