Name: Christopher Lester (email_not_shown)
Date: 02/11/02-07:40:40 PM Z

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,


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

This archive was generated by hypermail 2b29 : 01/23/19-02:40:01 PM Z CET