Quote by arivero
N=8 SUGRA. But it is a compactification of D=10 or D=11 SUGRA, isn't it? And it is related to a limit of string theory ...

I am not so sure about that.
It seems that duality in string theory relies basically on largeN limit considerations. So perhaps it's exactly the other way round: not ordinary gauge fields are (lowenergy) limits of strings, instead string theory may be the largeN limit auf certain gauge theories. If this is true, SUGRA may very well be an own candidate w/o the requirements to derive it from strings.
One question: which SUGRAs are the limits of certain string theory and which are not?