A Problem in Georgi's Lie algebras in particle physics

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Discussion Overview

The discussion focuses on understanding a specific equation (2.35) from the textbook "Lie Algebra in Particle Physics." Participants are examining the manipulation of transformation matrices and their relationship to trace operators within the context of Lie algebras in particle physics.

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant requests clarification on how transformation matrices can be extracted outside the trace operator in equation 2.35, suggesting a possible error in the textbook.
  • Another participant explains that in equation 2.34, the terms Ta and Td are vectors of matrices, while Lad is a vector of numbers, indicating that the product Lad Td is a scalar product rather than a matrix product.
  • This participant also mentions that the transformation matrices can be manipulated similarly with different indices and that L and L^-1 are equivalent in this context.
  • A later reply discusses the transformation of Ta and Tb and how the trace property Tr(AB) = Tr(BA) is applied to derive equation 2.35, asserting that the linearity of the trace allows for the extraction of certain terms.

Areas of Agreement / Disagreement

Participants express differing levels of understanding regarding the manipulation of the equations, and while some explanations are provided, there is no clear consensus on the correctness of the interpretations or the original equation.

Contextual Notes

There are potential limitations in the assumptions made about the nature of the products and the definitions of the terms involved, which may affect the clarity of the discussion.

zahero_2007
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Can some one please explain to me equation 2.35 on page 49 in the textbook "Lie algebra in particle physics " How can he extract the 2 Transformation matrices outside the trace operator ?I think there is something wrong
Sorry I do not know how to use latex
 
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in 2.34 Ta and Td are vectors of matrices. And Lad a vector of numbers so Lad Td is not a matrix product but a scalar product. You can put Lad near Td.
It would be the same with another index for Tb. L and L^-1 are the same
You can then multiply, take the traces and extract the numbers (not matrices)

I hope i wrote not too many wrong things!
 
I see , Thanks a lot naima .
 
When
Ta -> T'a = L [Lac.Tc] L-1
Tb -> T'b = L [Lbd.Td] L-1
then
TaTb -> L [ (Lac.Tc)(Lbd.Td)] L-1
You know that Tr(AB) = Tr (BA) so when you take the trace of the rhs you get
Tr ((Lac.Tc)(Lbd.Td))
Lac and Lbd are numbers and Rc Tc are matrices and as trace is linear so you get 2.35
 

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