Hello Group,
it is known that the anomalous electric dipole moment is violating P-
symmetry. I wonder whether adding the term describing Pauli
interaction of anomalous magnetic dipole moment with electromagnetic
field to the Dirac's lagrangean density violates any of C, P or T -
symmetries? (Of course I remember that it should be CPT invariant, so
if it violates any, it necessarily violates two of them )

I took the term:
bar{psi} (i/2)[gamma ^nu, gamma ^lambda] psi
(I've used common notation: psi's are Dirac's spinors, gamma's are
dirac's matrices)

transformed it and got that it:
- changes its sign under charge conjugation
- behaves like tensor under parity transformation and time reversal.
We know how electromagnetic field tensor F_{nu lambda} behaves under
those transformations so I got the finall result that the full
interaction term:

bar{psi} (miu/2) (i/2)[gamma ^nu, gamma ^lambda] F_{nu lambda}
psi
remains invariant. (miu is particle's magnetic moment)
Am I right?
Wish to hear any comments;
magda

Hello Group,
it is known that the anomalous electric dipole moment is
violating P-
symmetry. I wonder whether adding the term describing Pauli
interaction of anomalous magnetic dipole moment with
electromagnetic
field to the Dirac's lagrangean density violates any of C, P
or T -
symmetries? (Of course I remember that it should be CPT
invariant, so
if it violates any, it necessarily violates two of them )

I believe that anomalous magnetic dipole moment violates T.

On May 30, 1:01 am, Joseph Warner <Joseph.D.War... at (no spam) nasa.gov
wrote:


I believe that anomalous magnetic dipole moment violates T.


Hmmm, but how should I understand you "believe"? Do you mean
that we
should seek for a mathematical formula describing interaction
of this
(hyphothetical but still possible) physical feature of a
particle with
E-M filed that would have this (P-violating) property? (If
yes -
why???) Because the term proposed by Pauli, which I've used in
the
above calculations, doesn't violate any of them. I've risen
that
question as I wasn't sure whether I've made mistake or not.
with regards
m

This isn't too hard to see. Take a uniform magnetic field and a
charge particle. Let the particle's velocity be perpendicular to
the magnetic field, use the right hand rule to see the direction
of the deflection. Have the particle deflect until its velocity
in perpendicular to its original velocity. Now reverse its
velocity without changing its charge. You will see it does not
follow the same path. To make it follow the same path the charge
has to be reversed along with the velocity.