Singular Vertices in the Strong Coupling Phase of Four-Dimensional Simplicial Gravity

We study four-dimensional simplicial gravity through numerical simulation with special attention to the existence of singular vertices, in the strong coupling phase, that are shared by abnormally large numbers of four-simplices. We attempt to cure this disease by adding a term to the action which suppresses such singular vertices. For a sufficiently large coefficient of the additional term, however, the phase transition disappears and the system is observed to be always in the branched polymer phase for any gravitational constant.Comment: 11 pages, 7 Postscript figure

Scaling Behavior in 4D Simplicial Quantum Gravity

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

K_l3 form factor with two-flavors of dynamical domain-wall quarks

We report on our calculation of K \to \pi vector form factor by numerical simulations of two-flavor QCD on a 16^3x32x12 lattice at a \simeq 0.12 fm using domain-wall quarks and DBW2 glue. Our preliminary result at a single sea quark mass correponding to m_PS/m_V \simeq 0.53 shows a good agreement with previous estimate in quenched QCD and that from a phenomenological model.Comment: 6 pages, 5 figures, poster presented at Lattice2005 (Weak matrix elements); v2: a reference adde