Critical Collapse in the Axion-Dilaton System in Diverse Dimensions
  We study the gravitational collapse of the axion-dilaton system suggested by type IIB string theory in dimensions ranging from four to ten. We extend previous analysis concerning the role played by the global SL(2,R) symmetry and we evaluate the Choptuik exponents in the elliptic case. 
Luis Alvarez-Gaume, Ehsan Hatefi
gr-qc hep-th