Parity violation in weak decays

[JoePhysicsNut]

Homework Statement

I am confused about parity violation in weak decays. I learned about Wu's famous experiment and how it demonstrates that parity is violated in weak decays.

However, when I am doing a course problem on nuclear β-decay, then it still necessary to conserve parity.

Homework Equations

As an example, consider the
La_{57} (J^P=2^-) → Ce_{58} (J^P=0^+) decay, where I am asked to figure out what the angular momentum and spin state of the electron-neutrino system is.

The Attempt at a Solution

I get the right answer, when I require l=1 as this carries P=-1 and S_{enu}=1 to conserve angular momentum overall.

So my question is, why I am requiring parity to be conserved in nuclear β-decay when parity is violated for weak decays?

 

[Dick]

Homework Statement

I am confused about parity violation in weak decays. I learned about Wu's famous experiment and how it demonstrates that parity is violated in weak decays.

However, when I am doing a course problem on nuclear β-decay, then it still necessary to conserve parity.

Homework Equations

As an example, consider the
La_{57} (J^P=2^-) → Ce_{58} (J^P=0^+) decay, where I am asked to figure out what the angular momentum and spin state of the electron-neutrino system is.

The Attempt at a Solution

I get the right answer, when I require l=1 as this carries P=-1 and S_{enu}=1 to conserve angular momentum overall.

So my question is, why I am requiring parity to be conserved in nuclear β-decay when parity is violated for weak decays?

Because parity is usually NOT violated. The exception doesn't make the rule. Even then it's not violated by much. Only certain cases in the quark mixing matrix will you get any significant violation at all. That's why it took till 1956 to discover. It's a perfectly fine approximate symmetry.

 

[JoePhysicsNut]

Because parity is usually NOT violated. The exception doesn't make the rule. Even then it's not violated by much. Only certain cases in the quark mixing matrix will you get any significant violation at all. That's why it took till 1956 to discover. It's a perfectly fine approximate symmetry.

But in Wu's experiment, ALL the electrons come out in one direction making parity MAXIMALLY violated.

 

[Dick]

But in Wu's experiment, ALL the electrons come out in one direction making parity MAXIMALLY violated.

Oh heck. I was thinking about CP violation. Different thing. Sorry!