Parity and magnetic fields

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Parity and magnetic fields

Post by deaste » Tue Sep 15, 2020 10:04 pm

I have an article by Robert Adair, who was one of the researchers of CP-asymmetry at Brookhaven.

But this post is primarily about his discussion of parity symmetry and how a magnetic field around a copper wire doesn't have reflection symmetry.

I learned that the right hand rule is a way to define the current and the circulation of the magnetic field, so for instance a current flowing left to right in a straight wire, will have a magnetic field oriented the same way as the fingers if the right hand is aligned so the thumb points in the current's direction, and the fingers curl around the wire.

Clearly a reflection in a mirror will not change the current's direction but will change the magnetic field (so a "left hand rule" is needed). This will be the case for wire loops too. Adair says that a current flowing anticlockwise will have a magnetic field pointing downwards, I don't think that's right.
He goes on to say that a sample of cobalt-60 placed in this field will emit electrons in the up direction because the nuclear spins will align with the magnetic field (inside the loop or coil), which as mentioned he says points downwards.

What am I missing here?

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