Critical string models
In type IIB supergravity the dilaton/string coupling constant and the degree-1 RR-field of the D(-1)-brane combine into a complex function
which transforms under the modular group S-duality U-duality as
This combined field is also called the axio-dilaton.
Revised on November 13, 2015 13:23:16
by Urs Schreiber