Parity Violation The Biggest Scientific Blunder of the

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

Is Nature Symmetrical? We thought so until 1956 !! A Major change in our view of space and time 1. Round Earth 2. Heliocentric view of Universe 3. Special Relativity (time is not absolute) 4. General relativity (spacetime is curved) 5. Big bang – Universe finite in space and time 6. Expanding Universe (time asymmetry) Mark Hadley

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

Space Inversion = reflection + 180° rotation Axial or Pseudo vector Mark Hadley

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

Effect of Parity - spin Before After Mark Hadley

Parity violation in the weak interactions Tsung Dao Lee Chen Ning Yang Physical Review October 1956 p 254 -258 Mark Hadley

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

Experimentalists Wu Ambler Hayward Hoppes Hudson National Bureau of Standards USA 1956 Mark Hadley

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

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

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: Mark Hadley

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 Mark Hadley

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

Doh !

Explanations using GR • Boundary Conditions • Common source Mark Hadley

Doh !! Doh!!

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

Parity in Newtonian Mechanics Before F = ma After Parity conserved F = m(-a) -F = m (-a) -F = (-m)(-a) E = ½m v 2 (± )E = ½(± m) v 2 Mark Hadley

Parity in Newtonian Mechanics P operator is chosen: 1) For simplicity 2) To conserve parity 3) Supported by: Special Relativity: (t-component of the energy momentum 4 -vector) General Relativity: Mark Hadley

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

Parity in Electromagnetism Before F = q(E + v x B) Parity conserved 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)) Mark Hadley

Parity on magnetic poles

Parity in electromagnetism e- e- e- ee- Magnetic field pointing out

e- eeee- Magnetic field pointing in

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

Parity in Electromagnetism P operator is chosen: 1) To conserve parity 2) For simplicity 3) Supported by the covariant formulation: In this order

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? Mark Hadley

“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 ! Mark Hadley

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

Parity • Reverses – Momentum – Lepton number etc. – Charge • Unchanged – Spin Is conserved Mark Hadley

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

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

Parity violation How could they get it so wrong? Mark Hadley

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! Mark Hadley

Parity is Conserved Mark Hadley

Eigenvectors of P, H, J 3 with eigenvalues 0, M, σ Parity Lorentz Boost Mark Hadley

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. Mark Hadley