Difference in phase convention for Wigner d-function

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SUMMARY

The discussion centers on the phase convention discrepancies between the Condon-Shortley-Wigner and Edmonds conventions for Wigner d-functions. The user identifies a specific example involving the Wigner-d matrix coefficients, particularly d^1/2_{-1/2,1/2}, which is computed as sin(theta/2) according to Condon-Shortley-Wigner. However, the Edmonds convention introduces an erroneous negative sign in the formula, leading to confusion. The conclusion reached is that the Edmonds reference contains a typo, specifically the inclusion of the term (-1)^{j-m} which should be omitted.

PREREQUISITES
  • Understanding of Wigner d-functions and their applications in quantum mechanics.
  • Familiarity with the Condon-Shortley phase convention.
  • Knowledge of the Edmonds phase convention as outlined in "Angular Momentum in Quantum Mechanics".
  • Basic proficiency in programming for computational physics, particularly in calculating matrix coefficients.
NEXT STEPS
  • Review the derivation of Wigner d-functions in quantum mechanics.
  • Examine the differences between Condon-Shortley and Edmonds phase conventions in detail.
  • Implement a program to compute Wigner-d matrix coefficients using both conventions for comparison.
  • Investigate common typographical errors in quantum mechanics literature and their implications on calculations.
USEFUL FOR

Physicists, quantum mechanics students, and computational physicists who are working with angular momentum theory and Wigner d-functions will benefit from this discussion.

chafelix
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I am looking for a way to connect the Condon-Shortley-Wigner to the Edmonds phase convention. Specifically I am writing a program to compute Wigner-d matrix coefficients

From tabulated values (e.g. even Wikipedia) d^1/2_{1/2,-1/2}=(-1)^{-1/2-1/2}d^1/2_{-1/2,1/2}=-sin(theta/2)

So d^1/2_{-1/2,1/2}=sin(theta/2)

But from Edmonds, eq. 4.1.27 with j=1/2,m=-1/2 this should have a - sign
e.g.
d^j_{mj}=(-1)^{j-m}[(2j)!/((j+m)!(j-m)!]^{1/2} [cos(theta/2)]^{j+m} [sin(theta/2)]^{j-m}

i.e. j=1/2, m=-1/2,j+m=0,j-m=1

- sqrt(1!/(0! 1!)) [cos(theta/2)]^0 [sin(theta/2)]^1, i.e. the sign is off


Is this an Edmonds typo or some different phase convention?
 
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I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?
 
Yes, Edmonds has a typo. There should be no (-1)**(j-m) there.
 

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