[R] Latex-Style Characters in R

[Lorenzo Isella]

Dear All,
I am starting to use R excellent graphical facilities to produce
good-looking plots.
However, I do not know yet how for use  pedices/apices (e.g. when you
write cm^3) and Greek letters (e.g. \sigma) which I really need now.
Is there a special package to load? Could anyone post a simple example
of such a plot so that I can re-use it?
Cheers

Lorenzo