Decay rho->eta + pion is forbidden.why?

  • Context: Undergrad 
  • Thread starter Thread starter nur.alifah
  • Start date Start date
  • Tags Tags
    Decay Pion
Click For Summary

Discussion Overview

The discussion centers on the decay process of the rho meson into an eta meson and a pion, specifically exploring why this decay is considered forbidden. The scope includes theoretical considerations related to symmetries in particle physics, particularly G-parity, and the implications for strong and weak interactions.

Discussion Character

  • Debate/contested

Main Points Raised

  • Some participants assert that the decay violates G-parity.
  • Others note that charge conjugation (C) is not a good symmetry for charged particles.
  • One participant expands on the role of G-parity, suggesting it is conserved in strong interactions but not in weak or electromagnetic interactions, indicating that while the decay is suppressed in weak processes, it should still be allowed.
  • Another participant mentions that weak decays are significantly suppressed by coupling constants, potentially by 10 to 15 orders of magnitude, and suggests that small isospin violation in strong interactions may be more relevant.
  • A participant questions whether the decay is forbidden solely due to isospin violation, given that strangeness is conserved.
  • One participant claims that the decay occurs via electromagnetic interaction with an intermediate virtual photon, reiterating the importance of G-parity.

Areas of Agreement / Disagreement

Participants generally agree that G-parity plays a critical role in the discussion, but there are competing views on the implications of weak decays and the relevance of isospin violation. The discussion remains unresolved regarding the exact reasons for the decay being forbidden.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the interactions involved and the specific conditions under which G-parity applies. The role of phase space considerations in decay processes is also mentioned but not fully explored.

nur.alifah
Messages
3
Reaction score
0
decay rho-->eta + pion is forbidden.why?

is it only violation of charge conjugate or its not conserve the energy & momentum.
 
Physics news on Phys.org


It violates G-parity.

C is not a good symmetry for charged particles.
 


Vanadium 50 said:
It violates G-parity.

C is not a good symmetry for charged particles.

To expand a bit on this (and please feel free to correct me if I am wrong), G-parity is conserved in strong interactions but not in weak or electromagnetic. So, [tex]\rho \rightarrow \pi\pi[/tex] dominates the decay of a rho since it is a strong decay, but the decay [tex]\rho \rightarrow \eta \pi[/tex] should still be allowed for a weak process, albeit suppressed in comparison to the 2 pion channel due to phase space considerations.
 


Yes, but weak decays are suppressed by the couplings. You'll be down 10, 12 maybe 15 orders of magnitude. The small isospin violation in the strong interaction is probably more important.
 


the strangeness is conserve,
so,is it only the isospin violate make this decay forbidden?
 


It is only the G parity. The decay occurs via the EM interaction, with an intermediate virtual photon.
 

Similar threads

Undergrad Tau Decay: More Pions, Less Ratio?
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad What is the meaning of 'CP violation' in the Cronin and Fitch experiment?
  • · Replies 10 ·
Replies
10
Views
2K
Undergrad Forbidden decay ##\rho^0\rightarrow \pi^0\pi^0##
  • · Replies 4 ·
Replies
4
Views
4K
Undergrad Why does the long-lived kaon only rarely decay to two pions?
  • · Replies 2 ·
Replies
2
Views
2K
High School CERN Experiment NA62 observes rare Kaon decay mode
  • · Replies 7 ·
Replies
7
Views
4K
Undergrad Pion+/- decay - what *Exactly* is happening?
  • · Replies 46 ·
2
Replies
46
Views
7K
Undergrad Pion Detection: Finding a Film for Interference Experiment
  • · Replies 3 ·
Replies
3
Views
2K
Graduate K-Long and K-Short pion decay cross sections
  • · Replies 3 ·
Replies
3
Views
3K
Undergrad Forbidden decays and conservation laws
  • · Replies 10 ·
Replies
10
Views
3K
Undergrad Isobar states decay probabilities
  • · Replies 1 ·
Replies
1
Views
1K