Decay of W+ Boson: Up+Anti-Down & Charm+Anti-Strange

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    Boson Decay
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Discussion Overview

The discussion centers on the decay modes of the W+ boson, specifically why it decays into certain quark-antiquark pairs such as up + anti-down and charm + anti-strange, while questioning the possibility of decaying into up + anti-strange. Participants explore concepts related to charge conservation, baryon number, and the implications of the Cabibbo angle.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the decay modes of the W+ boson and suggests that the Cabibbo angle might be relevant.
  • Another participant asserts that the W+ boson can decay into up + anti-strange, referencing a book as a source of their information.
  • A different participant disputes the decay into up + anti-strange, arguing that it would imply an incorrect isospin for the W+ boson.
  • One participant notes that isospin is not conserved in weak interactions, prompting further discussion on the topic.
  • Another participant provides decay rate comparisons, indicating that certain decay modes occur at significantly different rates, suggesting a dependence on the CKM matrix.

Areas of Agreement / Disagreement

Participants express differing views on the decay modes of the W+ boson, with no consensus reached on the validity of specific decay channels or the role of isospin conservation in weak interactions.

Contextual Notes

Participants reference various sources and concepts, including the CKM matrix and isospin, but the discussion remains open-ended with unresolved questions about the implications of these factors on decay modes.

Who May Find This Useful

This discussion may be of interest to those studying particle physics, particularly in the context of weak interactions and quark decay processes.

malawi_glenn
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Hi I was wondering why the W+ boson is decaying into following quarks:

up + anti(down)

charm + anti(strange)

bot not:

up + anti(strange) [for example]

both electric charge and baryon number is conserved.

What am I missing? Is it the Cabibbo angle?
 
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I thought W^+ does -->u+sbar.
 
Meir Achuz said:
I thought W^+ does -->u+sbar.

not according to my book, Povh "nuclei and particles.."

and it can't be because of the cabibbo mixing.. must ask someone at my university i guess =)
 
Meir Achuz said:
I thought W^+ does -->u+sbar.

No, it does not. W+ --> u + sbar would cause the W+ to have isospin-1/2, which it clearly cannot have. It can only have isospin-1 (for u + dbar) or isospin-0 with S=1, C=1 (for c + sbar). Similarly, Z can only have isospin-0 or 1, with only quark-antiquark pairs forming in decay products.
 
Last edited:
But those isospinn is not conserved in weak interaction, right?
 
W could decay to us,cd. but compare to ud,cs, it's rate is small. W->us,cd rates are around 1.7%. but to ud,cs,the rates around 32%. you could find the difference in CKM.
 
malawi_glenn said:
But those isospinn is not conserved in weak interaction, right?

Ummm... yes this is correct.
 

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