# Physical interpretation of superstrings

The scalar fields $X^\mu$ in bosonic string theory have a clear physical interpretation - they describe the embedding of the string in spacetime.

Adding fermionic fields on the worldsheet is a generalization for sure, gives fermions in the spectrum, has a smaller critical dimension and no tachyons, that's all good - but I don't see how they can have any physical interpretation as nice as the above for the scalars - isn't everything about how a string moves in spacetime described by the $X^\mu$ part?

-
Btw, there's no necessity for a clear geometric interpretation in string theory. As far as I understand, any 2D CFT with vanishing central charge can be regarded as a string theory and some CFTs have no clear interpretation as a sigma model. – Squark Dec 15 '11 at 12:10