Why Do Muons Decay in Particle Physics?

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Discussion Overview

The discussion centers on the decay of muons in particle physics, exploring the reasons behind their instability and the mechanisms involved in their decay into electrons and neutrinos. Participants delve into theoretical aspects, including the role of energy levels and interactions within the Standard Model.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant notes that while muons are described as unstable and decay into electrons and neutrinos, the underlying reasons for this decay are not well-explained in literature, suggesting it may relate to energy levels.
  • Another participant agrees that the muon decays into a lighter electron and explains this in terms of energy states, comparing it to an excited atom that decays to a lower energy state.
  • A different participant introduces the idea of "Nature abhors vacuum," implying that there are additional factors influencing decay rates, though specifics are not provided.
  • Further, a participant mentions that the decay process is facilitated by a coupling term in the Standard Model involving the W minus boson, indicating that without this term, the decay would be much rarer and occur less frequently.

Areas of Agreement / Disagreement

Participants express various viewpoints regarding the reasons for muon decay, with some agreeing on the role of energy levels and coupling terms, while others introduce different concepts without reaching a consensus on the primary factors involved.

Contextual Notes

Some assumptions about the nature of particle interactions and the implications of the Standard Model are not fully explored, leaving certain aspects of the discussion open to interpretation.

kidsmoker
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In all the books I've been reading it just states that muons are unstable and that they decay into an electron and a neutrino (all be it with a relatively long life-time compared to some other particles). But it says nothing about why the muon actually decays. I assume it's something to do with it wanting to lower its energy but i'd like to know a bit more detail if I could.

Thanks!
 
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You are correct, the electron is a ligher particle and the muon can decay to it, and will do it.

http://en.wikipedia.org/wiki/Particle_decay

You can naively think of this as the excited atom: The extited atom has higher mass then the atom in its ground state (since the electron has gained energy so it can occupy a higher state), the excited state can and will decay to the ground state again.
 
malawi_glenn said:
You are correct, the electron is a ligher particle and the muon can decay to it, and will do it.

On the same token, Nature abhors vacuum and because of it the quicksilver will ascend the tube.

The good question is "how many centimeters?". Or here, "at what rate?"
 
Okay cool, thanks. So unnecessarily high energy levels and vacuum. Anything else? :p
 
kidsmoker said:
Okay cool, thanks. So unnecessarily high energy levels and vacuum. Anything else? :p

A key point is that the process occurs (at tree level) because in the Standard Model there is a term that couples those particle together to a W minus boson (the story is actuallly a bit more subtle but that's the basic point). If there was no such term, the process might still occur but it would be much rarer (so the lifetime would be much longer) because it could only occur with Feynman diagrams containing loops which suppress the process.
 

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