We study the gravitational collapse of the axion-dilaton
system suggested by type IIB string theory in dimensions ranging from four to
We extend previous analysis concerning the role played by
the global SL(2,
R) symmetry and also we explain ,why we do have three
different assumptions(cases). We evaluate the Choptuik exponents in the
Eventually we try to explain some of the open
questions for two other assumptions and future directions.