Dr Mark Hadley

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
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Effect of Parity - momentum
The Parity Operator gives the transformation due
an inversion of the spatial coordinates

• Before

• After

6
Effect of Parity - spin

• Before

• After

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Physical Review October 1956 p254-258
Parity violation in the weak interactions
Tsung Dao Lee
Chen Ning Yang
8
Start with a symmetrical state
Look for an asymmetric outcome
e-
?
60Ni e- ?e
60Co
I(?)d? k (1 acos? )sin?d?
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Experimentalists
Wu   Ambler   Hayward
 Hoppes  Hudson
National Bureau of Standards USA 1956
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actual result
I(?)d? k (1 v/c cos? )sin?d?
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 ß 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

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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

?
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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?

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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
?
?
?
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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

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Parity in electromagnetism
Start with a symmetrical state
e-
Magnetic field pointing out
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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))
?
?
?
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Parity on magnetic poles
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Parity in electromagnetism
e-
Magnetic field pointing out
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e-
Magnetic field pointing in
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Duality Transforamtion

• The roles of E and B can be reversed by a duality
  transformation

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Parity in Electromagnetism

• P operator is chosen
• To conserve parity
• For simplicity
• Supported by the covariant formulation

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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?
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• We see from this analysis that the logical path
  from the observed asymmetry to the inferred
  nonconservation of parity in ß 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 !
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What is the mirror image of a Cobalt atom?
60Co
60Co
e-
(not to scale)
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Parity

• Reverses
• Momentum
• Lepton number etc.
• Charge
• Unchanged
• Spin

• Is conserved

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Conclusions

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

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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
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Parity violation
How could they get it so wrong?
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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!
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Parity isConserved
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Eigenvectors of P, H,J3 with eigenvalues 0,M,s
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.