Pion decaying to two neutrons demonstrates odd parity

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    Neutrons Parity Pion
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Discussion Overview

The discussion revolves around the decay processes involving pions and neutrons, specifically focusing on the parity of the final state in the context of particle physics. Participants explore the implications of Fermi-Dirac statistics on the allowed states of identical fermions in the decay process.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on the reasoning behind determining the parity of two neutrons in the final state of a pion decay, referencing a specific source.
  • Another participant corrects the initial misunderstanding, stating that the process discussed is not a pion decaying to two neutrons but rather a pion interacting with a deuteron.
  • A participant acknowledges the correction and presents the allowed two-neutron final states, noting their characteristics as identical fermions.
  • There is a question regarding the antisymmetry of the 1s0 state, given its classification as a singlet state with specific quantum numbers.
  • Another participant asserts that the 1s0 state is not relevant to the reaction, indicating that only the 3p1 state is possible according to the referenced material.

Areas of Agreement / Disagreement

The discussion features corrections and clarifications, but there is no consensus on the implications of the final states or the validity of the initial claims regarding the pion decay process.

Contextual Notes

Participants express uncertainty regarding the antisymmetry of certain states and the specific conditions under which the decay processes are analyzed, highlighting potential limitations in their understanding of the quantum mechanical principles involved.

Gene Naden
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Does anyone have a reference to a good explanation of this experiment. I am looking at https://quantummechanics.ucsd.edu/ph130a/130_notes/node323.html

I am unable to comprehend the reasoning by which it determines the parity of the two neutrons in the final state. Particularly when it says the requirement of F-D statistics restricts the spin and angular momentum of the final state.
 
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That is not a pion decaying to two neutrons. It is the reaction of a pion hitting a deuteron.
 
Yes, I gave the wrong reaction. Thank you for correcting me.

The reference says the allowed two-neutron final states are, because they are identical fermions,
1s0
3p0,1,2
1d2
3f2,3,4

I looked up the spectroscopic notation. It says 1s0 is a singlet state, L=1, with J=0. So how can it be antisymmetric?
 
It does not react to 1s0. Only 3p1 is possible, as explained in the website you linked.
 

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