The phase structure of four-dimensional simplicial quantum gravity coupled to a U (1) gauge field is investigated numerically with the dynamical triangulation method. A smooth phase is found in the region between the crumpled phase and the branched polymer phase. This new phase has a negative string susceptibility exponent. The phase transition between the smooth phase and the crumpled phase is studied using the finite size scaling method. From the numerical results we conclude that this model has a phase transition that is higher than first-order. Numerical results suggest a possibility of the existence of the continuum limit at the critical point. at University of Manchester on March 23, 2015 http://ptp.oxfordjournals.org/ Downloaded from where l ij denotes the link between vertices i and j, and t ijk denotes the triangle with vertices i, j and k. Here, o(t ijk ) is the number of 4-simplices sharing the triangle

Scaling relations in four-dimensional simplicial quantum gravity are proposed using the concept of the geodesic distance. Based on the analogy of a loop length distribution in the two-dimensional case, the scaling relations of the boundary volume distribution in four dimensions are discussed in three regions: the strong-coupling phase, the critical point and the weak-coupling phase. In each phase a different scaling behavior is found.Comment: 12 pages, latex, 10 postscript figures, uses psfig.sty and cite.st

No abstract

Four-dimensional(4D) spacetime structures are investigated using the concept of the geodesic distance in the simplicial quantum gravity. On the analogy of the loop length distribution in 2D case, the scaling relations of the boundary volume distribution in 4D are discussed in various coupling regions i.e. strong-coupling phase, critical point and weak-coupling phase. In each phase the different scaling relations are found.

The bosonic IIB matrix model, which contains the bosonic part of the IIB matrix model conjectured to be a non-perturbative definition of the type IIB superstring theory, is studied using a numerical method. The large N scaling behavior of the model is shown performing a Monte Carlo simulation. The expectation value of the Wilson loop operator is measured and the string tension is estimated. From the numerical results, the prescription of the double scaling limit is obtained.