What are the different decay processes shown in this Feynman diagram?

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Discussion Overview

The discussion revolves around various decay processes illustrated in a Feynman diagram, specifically focusing on the decay of particles such as electrons, positrons, and Higgs bosons. Participants explore theoretical aspects, conservation laws, and the implications of different decay channels within the framework of particle physics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants discuss whether processes involving electrons and positrons can be considered decay processes, particularly questioning the nature of photon decay into an electron-positron pair.
  • There is a proposal to consider the decay of a massive scalar boson, such as the Higgs boson, and its implications for decay processes.
  • Participants raise questions about the allowed decay processes of the Higgs boson, particularly regarding energy conservation and the conditions under which certain decays can occur.
  • Some participants mention the suppression of higher-order decay processes due to the complexity of interactions and phase space considerations.
  • Questions arise about the necessity of producing particles with their corresponding antiparticles in decay processes, particularly in relation to lepton number and charge conservation.
  • There is a discussion about the potential for the Higgs boson to decay into multiple lepton pairs, including electron-positron and muon-antimuon pairs, and the constraints imposed by the Standard Model.

Areas of Agreement / Disagreement

Participants express differing views on the classification of certain processes as decays, the implications of conservation laws, and the viability of specific decay channels. The discussion remains unresolved regarding the exact nature of some decay processes and the conditions under which they can occur.

Contextual Notes

Participants note that the mass of the Higgs boson must exceed certain thresholds for specific decay processes to occur, and that higher-order decays are generally suppressed due to their complexity and phase space limitations. There is also mention of the need for additional theoretical frameworks to accommodate certain decay processes not predicted by the Standard Model.

Who May Find This Useful

This discussion may be of interest to those studying particle physics, particularly in the context of decay processes, conservation laws, and the implications of different theoretical models in high-energy physics.

  • #31
failexam said:
I am adding that line, because each interaction vertex must have three lines popping out of it, with the Higgs for one line and the fermion and anti-fermion on the other two lines
But without having that extra higgs you still satisfy that! You just have one vertex less.
 
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  • #32
Got it!

Is this the only tree-level Feynman diagram for this process?
 
  • #33
No. You have two diagrams. One where the electron of the initial vertex is external and one where the positron is.
 
  • #34
I see! So, for a process like

$$h \rightarrow e^{+} + e^{-} + \mu^{+} + \mu^{-}$$

you have only the following two tree-level Feynman diagrams, right?

https://i.imgsafe.org/79327227a1.jpg

https://i.imgsafe.org/7932eec9b7.jpg
 
  • #35
No. You also have the diagrams where the initial vertex is with the electron line.
 
  • #36
Got it!

So, you have two tree-level Feynman diagrams for

$$h \rightarrow e^{+} + e^{-} + e^{+} + e^{-} $$

https://i.imgsafe.org/79814d363d.jpg

and four tree-level Feynman diagrams for

$$h \rightarrow e^{+} + e^{-} + \mu^{+} + \mu^{-}$$

https://i.imgsafe.org/7981a81e80.jpg

https://i.imgsafe.org/79820c6447.jpg,

right?
 
  • #37
wouldnt that work? h \rightarrow hh \rightarrow 2l 2l'?
Also these are not tree diagrams...
 
  • #38
ChrisVer said:
wouldnt that work? h \rightarrow hh \rightarrow 2l 2l'?
Also these are not tree diagrams...

Which ones are not tree-level Feynman diagrams?
 
  • #39
failexam said:
Which ones are not tree-level Feynman diagrams?
that was a conceptual mistake...
 
  • #40
Right, so all of the diagrams that I posted are tree-level diagrams, right?
 

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