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Is it possible, within FeynCalc, to work with expressions containing

structure constants from SU(N) groups with different values of N ?

For example, contractions of objects with SU(N) indices already yield

answers which depend on N in the desired way, such as:

SUNSimplify[SUNF[a,b,c] SUNF[a,b,d],SUNNToCACF -> False]

which evaluates to

N \delta_{c d}

as expected.

If however, I were to have a more complicated product of four

structure constants; two from SU(N) (contracted together) and two

from SU(M) (contracted together); then I would like to be able to

simplify the whole expression and obtain an answer like

N M \delta_{c d} \delta_{g h}.

Is it possible to attach particular dimensions M and N to different

structure constants?

Many thanks,

Christopher

P.S. I snooped around in the code FeynCalc.m a bit to see if I

could spot a solution in there, and I wondered if SUNF2[...] (as

opposed to SUNF[...]) might help me out, however SUNSimplify[...]

does not seem to simplify expressions composed of SUN2[...] objects,

so I guess I should leave them well alone ...

------------------------------------------------------

Christopher Lester Tel: +44 1223 766300

Cavendish Lab., Madingley Road, Cambridge, CB3 0HE, UK

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