Clebsch Gordan coefficients

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SUMMARY

The discussion centers on the Clebsch-Gordan coefficients, specifically the convention used in their calculation. It establishes that for angular momenta values of \( J_1 = 1 \) and \( J_2 = 1/2 \), the coefficient \(\langle 1 \quad 1/2 \quad 1/2 \quad 1|1 \quad 1/2 \quad 3/2 \quad 3/2\rangle\) equals 1, indicating a maximal value of angular momentum \( J = 3/2 \). The conversation also raises questions about conventions for the lowest values of angular momentum and suggests verifying results using a Clebsch-Gordan coefficients table.

PREREQUISITES
  • Understanding of angular momentum in quantum mechanics
  • Familiarity with Clebsch-Gordan coefficients
  • Knowledge of quantum state notation
  • Basic grasp of quantum operators, particularly \( J_- \)
NEXT STEPS
  • Study the derivation of Clebsch-Gordan coefficients in quantum mechanics
  • Explore the properties of angular momentum operators
  • Review the Clebsch-Gordan coefficients table for various \( J_1 \) and \( J_2 \) values
  • Investigate the implications of angular momentum coupling in quantum systems
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Physicists, particularly those specializing in quantum mechanics, students studying angular momentum coupling, and researchers working with Clebsch-Gordan coefficients in theoretical physics.

LagrangeEuler
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In CG coefficients methodology there is convention
\langle J_1 J_2 J_1 J-J_1|J_1 J_2 J J \rangle \geq 0
So if we have ##J_1=1##, ##J_2=1/2##
\langle 1 \quad 1/2 \quad 1/2 \quad 1|1 \quad 1/2 \quad 3/2 \quad 3/2\rangle \geq 0
using this convention. However, because ##J=3/2## is maximal value of angular moment, this is only CG coefficient and we could write
\langle 1 \quad 1/2 \quad1/2 \quad 1|1 \quad 1/2 \quad 3/2 \quad 3/2\rangle =1
Now if we work with ##J_-## operator we will obtain that
\langle 1 \quad 1/2 \quad -1/2 \quad -1|1 \quad 1/2 \quad -3/2 \quad -3/2\rangle =1
Do we have some similar convention for this lowest value of angular momentum?
 
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