  We discuss how: (i) a dilaton/axion superfield can play the role of a
Barbero-Immirzi field in four-dimensional conformal quantum supergravity
theories, (ii) a fermionic component of such a dilaton/axion superfield may
play the role of a Goldstino in the low-energy effective action obtained from a
superstring theory with F-type global supersymmetry breaking, (iii) this global
supersymmetry breaking is communicated to the gravitational sector via the
supergravity coupling of the Goldstino, and (iv) such a scenario may be
realized explicitly in a D-foam model with D-particle defects fluctuating
stochastically.
