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

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is nature symmetrical
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)
slide3
Plan
  • Parity violation – the conventional view
  • My interest
  • Review of Parity conservation
    • Mechanics
    • Electromagnetism
    • Weak Interactions
  • An alternative view
    • Parity is Conserved !!
space inversion
Space Inversion

Inversion = reflection + 180° rotation

Axial or Pseudo vector

effect of parity momentum
Before

After

Effect of Parity - momentum

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

physical review october 1956 p254 258
Physical Review October 1956 p254-258

Parity violation in the weak interactions

Tsung Dao Lee

Chen Ning Yang

start with a symmetrical state

Look for an asymmetric outcome

Start with a symmetrical state

e-

θ

60Ni + e- +υe

60Co

I(θ)dθ = k (1 + αcosθ )sinθdθ

experimentalists
Experimentalists

Wu   Ambler   Hayward  Hoppes  Hudson

National Bureau of Standards USA 1956

slide10

actual result

I(θ)dθ = k (1 –v/c cosθ )sinθdθ

nobel prize winners 1957
Nobel prize winners 1957

Parity violation in the weak interactions

Tsung Dao Lee

Chen Ning Yang

but not quite so simple
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:

a gravitational explanation for quantum theory
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
parity is violated fact
Parity is violated - FACT

The Nobel Prize Committee say so.

All the books say so.

explanations using gr
Explanations using GR
  • Boundary Conditions
  • Common source

slide17

Doh!!

Doh !!

where have they gone wrong
Where have they gone wrong?
  • Exactly what has been observed?
  • Exactly what has been violated?
  • What, exactly, is the definition of Parity?
parity in newtonian mechanics
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

parity in newtonian mechanics20
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:

slide21

e-

e-

e-

e-

e-

Parity in electromagnetism

Start with a symmetrical state……

e-

Magnetic field pointing out

parity in electromagnetism
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))

slide24

e-

e-

e-

e-

Parity in electromagnetism

e-

Magnetic field pointing out

slide25

e-

e-

e-

e-

e-

Magnetic field pointing in

duality transforamtion
Duality Transforamtion
  • The roles of E and B can be reversed by a duality transformation:
parity in electromagnetism27

In this order

Parity in Electromagnetism

P operator is chosen:

  • To conserve parity
  • For simplicity
  • Supported by the covariant formulation:
effect of parity
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?

slide29
“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 !

what is the mirror image of a cobalt atom

e-

e+

Anti 60Co

What is the mirror image of a Cobalt atom?

60Co

60Co

e-

(not to scale)

parity
Parity
  • Reverses
    • Momentum
    • Lepton number etc.
    • Charge
  • Unchanged
    • Spin
  • Is conserved
conclusions
Conclusions
  • Space Inversion is a symmetry of Nature
  • Parity is conserved
  • The conventional P operator is not conserved.
just a change of convention
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

parity violation
Parity violation

How could they get it so wrong?

how could they get it so wrong
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!

cp violation
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.
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