K-Long and K-Short pion decay cross sections

In summary, the conversation discusses the CP violation in the kaon system and the difference in decay rates between KS and KL due to the larger phase space for a decay into two pions. The question is raised about the contribution of a third pion and whether it can be neglected compared to the phase space effect. It is noted that strong interactions are not suppressed as much as electromagnetic interactions, but it is unclear if the contribution is smaller or larger than one.
  • #1
tg85
7
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?
 
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  • #2
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.
 
  • #3
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?
 
  • #4
Yes, and it is not even clear if that contribution is smaller or larger than one.
 

1. What is the significance of K-Long and K-Short pion decay cross sections?

The K-Long and K-Short pion decay cross sections are important in understanding the decay processes of these particles. They provide information about the probability of a K-Long or K-Short pion decaying into other particles and the resulting energy distribution.

2. How do the cross sections for K-Long and K-Short pion decay compare?

The cross section for K-Long pion decay is about 10 times larger than that of K-Short pion decay. This is due to the fact that K-Long pions have a longer lifetime and therefore have a higher chance of decaying before interacting with other particles.

3. What factors influence the cross sections for K-Long and K-Short pion decay?

The cross sections for K-Long and K-Short pion decay are influenced by several factors, including the energy of the pions, the type of particles they decay into, and the angle at which they are measured. These cross sections can also be affected by the presence of external fields or interactions with other particles.

4. How are the cross sections for K-Long and K-Short pion decay experimentally determined?

The cross sections for K-Long and K-Short pion decay are measured through scattering experiments, where a beam of pions is directed at a target and the resulting decay particles are detected and analyzed. These experiments can be performed at particle accelerators or using cosmic ray detectors.

5. What applications do the K-Long and K-Short pion decay cross sections have in particle physics?

The study of K-Long and K-Short pion decay cross sections provides important insights into the fundamental interactions and properties of subatomic particles. These cross sections are used in the development and testing of particle physics theories, and can also have practical applications in fields such as medical imaging and radiation therapy.

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