Weak nuclear Vs Strong nuclear

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Discussion Overview

The discussion revolves around identifying the responsible force in particle interactions, specifically examining the decay of a K- meson into three charged pi mesons. The focus is on the weak nuclear force and its characteristics compared to the strong nuclear force.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions how to determine which force is responsible for a particle interaction, using the decay of a K- meson as an example.
  • Another participant suggests that the weak interaction is involved due to the kaon's relatively long lifetime of about 10^-8 seconds, contrasting with the much shorter timescale of strong interactions (about 10^-23 seconds).
  • It is proposed that the conservation of strangeness in strong interactions indicates that if strangeness changes, the weak interaction must be involved.
  • A later reply emphasizes that while strangeness is a key factor in this specific case, it cannot be generalized as the sole criterion for determining the type of interaction.
  • Another participant recommends analyzing the quark and lepton content in the initial and final states and using Feynman diagrams to assess the possible interactions, noting that if a quark or anti-quark is missing from either state, the weak interaction must be involved.

Areas of Agreement / Disagreement

Participants express differing views on the role of strangeness in determining the type of interaction, with some suggesting it is a key factor while others caution against generalizing this approach. The discussion remains unresolved regarding a definitive method for identifying the responsible force.

Contextual Notes

Participants acknowledge that the determination of the responsible force may depend on specific conditions and the presence of certain particles, highlighting the complexity of particle interactions.

jpa
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How do you determine in a particle interaction which force is responsible?

For example

a K- meson is found to decay into three charged pi mesons what force is involved?

The answer here is a weak interaction but why?
 
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Two reasons. First, the kaon lifetime is about 10-8 sec, and strong interactions typically occur in 10-23 sec. Second, strangeness is changed in the kaon decay and the strong interaction conserves it.
 
So could we say that strangeness number is the key.
If its conserved then the interaction was via the strong nuclear else its weak nuclear!
 
The key in this case, but it cannot be generally stated that that is the case.

A safe way to figure this out is to see what quarks/leptons exist in initial and final state and then write down feynman diagrams describing the transition from one into the other. If it can occur via the strong interaction, it will, if not then the weak interaction has a chance.

If there is a quark(anti-quark) which exist in only the initial state OR only the final state without its corresponding anti-quark(quark) the weak interaction has to play a part.

Hope that helps.
 

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