\eta\to\pi^0\gamma decay (Why this decay is forbidden by J?)

  • Thread starter Alex_Rob
  • Start date
  • #1
1
0

Main Question or Discussion Point

Decay \eta\to\pi^0\gamma is forbidden by C parity. But why this decay is also forbidden by statistics (J)?

pi^0 spin is 0
photon spin is 1

But there are can be different situations with full orbital angular momentum of pi^0\gamma.
J=L+S and must be 0. Look like L is 0. But why? Why we can't have L=1 in this case? (unlike in \rho\to\pi^0\gamma decay)
 
Last edited:

Answers and Replies

  • #2
ChrisVer
Gold Member
3,337
440
I would say that your first has spin 0, while the product has a spin 0 particle and a photon which is a spin 1 particle.
 
  • #4
ChrisVer
Gold Member
3,337
440
Again I am saying that the rho has J=1, so angular momentum conservation does not prohibit it to decay in a J=1 + J=0 particle.
The eta has J=0. And you try to make it decay into a J=1 and a J=0 particle? you can't compare these.
It's not only the CG coefficients, keep reading the conversation.

If you try to make the last configuration of pi0 and gamma to have a total angular momentum 0, then you have to set the orbital angular momentum of the two products to be L=1.
But then you are having an antisymmetric wavefunction describing your boson final states
 
  • Like
Likes Alex_Rob
  • #5
Vanadium 50
Staff Emeritus
Science Advisor
Education Advisor
2019 Award
24,813
7,820
I think this is much easier to see semiclassically: you are asking if a 0- --> 0- + radiation state is possible. It is not. A 0- state can have only monopole moments, and there are no magnetic monopoles, and the electric monopole is simply charge: zero in this case. Since no moment changes, there can be no radiation.
 
  • Like
Likes Alex_Rob

Related Threads on \eta\to\pi^0\gamma decay (Why this decay is forbidden by J?)

Replies
4
Views
7K
Replies
5
Views
4K
Replies
4
Views
882
  • Last Post
Replies
1
Views
2K
Replies
1
Views
570
  • Last Post
Replies
6
Views
6K
  • Last Post
Replies
1
Views
5K
Replies
10
Views
1K
  • Last Post
Replies
7
Views
1K
  • Last Post
Replies
2
Views
3K
Top