Membrane pregeometry and the vanishing of the cosmological constant

The authors suggest a model of induced gravity in which th fundamental object is a relativistic membrane minimally coupled to a background metric and to an external three-index gauge potential. They compute the low-energy limit of the two-loop effective action as a power expansion in the surface tension. A generalized bootstrap hypothesis is made in order to identify the physical metric and gauge field with the lowest-order terms in the expansion of the vacuum average of the composite operators conjugate to the background fields. They find that the large-distance behaviour of these classical fields is described by the Einstein action with a cosmological term plus a Maxwell-type action for the gauge potential. The Maxwell term enables one to apply the Hawking-Baum (1983,1984) argument to show that the physical cosmological constant is 'probably' zero.