K-Long and K-Short pion decay cross sections

  • Context: Graduate 
  • Thread starter Thread starter tg85
  • Start date Start date
  • Tags Tags
    Cross Decay Pion
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
Sign up Log in
3 replies · 3K views
tg85
Messages
6
Reaction score
2
In the text-book example of CP violation in the kaon system, the usual statement is that the KS decays much faster than the KL because the phase space is larger for a decay into two pions, compared to three pions. (See, for example, Griffiths or "Modern Particle Physics" by Thomson.)

I was wondering if that is the only large contribution. Doesn't a third pion add at least two gluon vertices to the highest-order Feynman diagram? Can this be neglected in comparison with the phase space?
 

Discussion

Physics news on Phys.org
The point with strong interactions is that they are ... well ... strong. Adding gluon vertices does not supress the amplitudes by a large amount as adding EM vertices does.
 
Orodruin said:
The point with strong interactions is that they are ... well ... strong. Adding gluon vertices does not supress the amplitudes by a large amount as adding EM vertices does.
OK, thanks. So there is a contribution, but it's much smaller than the phase space suppression?