Why does sd replace sγ5d ee in the amplitude of meson decay?

In summary, the conversation discusses the difference between the amplitudes of pure leptonic decay and semileptonic decay of a pseudoscalar meson. The reason for the change in amplitude is due to the conservation of parity, as the meson and final state have negative parity while the current must have positive parity. The inclusion of a parity violating operator is necessary for pure leptonic decay due to the lack of parity conservation in the transition to the vacuum state.
  • #1
plasmon
36
1
M=sγ5d ee
is the amplitude of pure leptonic decay of pseudo scalar meson(say K→ee), while
M=sd ee
is the amplitude of the semileptonic decay of K→π ee. Kindly explain why does sd replace sγ5d ee in the amplitude?
 
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  • #2
It's about the parity conservation. The K has negative parity, as does the pion (pseudoscalars). On the right hand side, two electrons have positive parity, so the current should have negative parity, -1*-1=1.

Then for the PS to PS decay you have a final state with negative parity, so only currents with positive parity can contribute.

The gamma5 is negative parity.
 
  • #3
I understand that the transition K→π conserves parity. While in pure leptonic decay, the quark current transition K→Vacuum does not conserve parity so it must include parity violating operator.
 

1. What is the Amplitude of Decay of Mesons?

The Amplitude of Decay of Mesons refers to the measure of how quickly a meson particle decays or breaks down into other particles. It is a fundamental property of mesons that is used to understand their behavior and interactions.

2. How is the Amplitude of Decay of Mesons calculated?

The Amplitude of Decay of Mesons is calculated using quantum field theory, specifically the Feynman diagram technique. This involves considering the initial and final states of the decay process and calculating the probability amplitude for the meson to transition from one state to another.

3. What factors affect the Amplitude of Decay of Mesons?

The Amplitude of Decay of Mesons can be affected by various factors such as the mass and spin of the meson, the interaction between the decay products, and the energy of the decay process. Additionally, the type of meson and the environment it is decaying in can also play a role.

4. Why is the Amplitude of Decay of Mesons important in particle physics?

The Amplitude of Decay of Mesons is important in particle physics as it provides crucial information about the nature of mesons and their interactions with other particles. It also helps in understanding the underlying fundamental forces and laws of the universe.

5. How is the Amplitude of Decay of Mesons used in research?

The Amplitude of Decay of Mesons is used in research to study the properties of mesons and their role in the Standard Model of particle physics. It is also used to investigate the behavior of matter and antimatter, as well as to explore new theories and phenomena in the field of particle physics.

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