  Four-dimensional (4D) simplicial quantum gravity coupled to U(1) gauge fields
has been studied using Monte-Carlo simulations. A negative string
susceptibility exponent is observed beyond the phase-transition point, even if
the number of vector fields (NV) is 1. We find a scaling relation of the
boundary volume distributions in this new phase. This scaling relation suggests
a fractal structure similar to that of 2D quantum gravity. Furthermore,
evidence of a branched polymer-like structure is suggested far into the
weak-coupling region, even for NV > 1. As a result, we propose new phase
structures and discuss the possibility of taking the continuum limit in a
certain region between the crumpled and branched polymer phases.
