Towards formulating an invariant Lagrangian

In summary, the conversation discusses a Lagrangian containing terms involving partial derivatives and a complex matrix. The question is whether the matrix can be substituted for one of the terms in the Lagrangian. However, simply writing out the matrix in the Lagrangian does not work, as it does not match the term being replaced.
  • #1
Safinaz
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Assuming a Lagrangian proportional to the following terms:

##L \sim ( \partial_\mu \sigma) (\partial^\mu \sigma) - g^{m\bar{n}} g^{r\bar{p}} (\partial_\mu g_{mr} ) ( \partial^\mu g_{\bar{n}\bar{p}} ) ~~~~~ \to (1) ##

Where ##\mu =0,1,2,3,4## and m, n,r, p and ##\bar{n}, \bar{p}, \bar{m}## and ##\bar{r}## = 1,2,3 ( complex coordinates )

Now if I have a complex matrix

##G_{a \bar{b}} \sim g^{m\bar{n}} g^{r\bar{p}} (\partial_a g_{mr} ) ( \partial_{\bar{b}} g_{\bar{n}\bar{p}} ) ~~~~~~~~ \to (2) ##

where ##a, \bar{b}= 1, ..., h_{2,1}##and ##h_{2,1}## is an arbitrary large number.

The question now, can I sub. by ##G_{a \bar{b}}##from equ. (2) into equ. ( 1) ? with the summation on the derivatives has different degrees of freedom? Literally, can I write the Lagrangian as:

##L \sim ( \partial_\mu \sigma) (\partial^\mu \sigma) - G_{a \bar{b}} G^{a \bar{b}} ##?

Any help appreciated!
 
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  • #2
Maybe I am misunderstanding your notation, but just ##G_{a\bar{b}}G^{a\bar{b}}## written out is not the term you are replacing in the lagrangian (even ignoring the different number of terms that would be summed), so how are you supposing this should work?
 

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