Gravitational Localization of All Local Fields on the Brane

We present a new $(p - 1)$-brane solution to Einstein's equations in a general space-time dimension. This solution is a natural generalization of the stringlike defect solution with codimension 2 in 6 space-time dimensions, which has been recently discovered by Gogberashvili and Singleton, to a general $(p - 1)$-brane solution with codimension $n$ in general $D = p + n$ space-time dimensions. It is shown that all the local fields are localized on the brane only through the gravitational interaction although this solution does not have a warp factor and takes a finite value in the radial infinity. Thus, this solution is a solution in an arbitrary space-time dimension realizing the idea of "gravitational trapping" of the whole bulk fields on the brane within the framework of a local field theory. Some problems associated with this solution and localization are pointed out.Comment: 12 pages, no figures, Late

Topological Symmetry, Background Independence, and Matrix Models

We illustrate a physical situation in which topological symmetry, its breakdown, space-time uncertainty principle, and background independence may play an important role in constructing and understanding matrix models. First, we show that the space-time uncertainty principle of string may be understood as a manifestation of the breakdown of the topological symmetry in the large $N$ matrix model. Next, we construct a new type of matrix models which is a matrix model analog of the topological Chern-Simons and BF theories. It is of interest that these topological matrix models are not only completely independent of the background metric but also have nontrivial "p-brane" solutions as well as commuting classical space-time as the classical solutions. In this paper, we would like to point out some elementary and unsolved problems associated to the matrix models, whose resolution would lead to the more satisfying matrix model in future.Comment: 19 pages, LaTex, Invited paper to appear in the special issue of the Journal of Chaos, Solitons and Fractals on "Superstrings, M, F, S, ....... Theory", edited by M.S. El Naschie and C. Castr

Evaporation of Three Dimensional Black Hole in Quantum Gravity

We discuss an evaporation of (2+1)-dimensional black hole by using quantum gravity holding in the vicinity of the black hole horizon. It is shown that the black hole evaporates at a definite rate by emitting matters through the quantum tunneling effect. A relation of the present formalism to the black hole entropy is briefly commented.Comment: 13 pages, phyzz

Antisymmetric Tensor Fields in the Locally Localized Gravity Models

We study the localization property of antisymmetric tensor fields in the locally localized gravity models. It is shown that all the antisymmetric tensor fields, including the vector field, in a bulk space-time are trapped on an $AdS$ brane by a gravitational interaction where the presence of the brane cosmological constant plays an important role as in the cases of the other bulk fields. The normalized zero-modes spread rather widely in extra space so small extra dimensions might be needed in order not to conflict with experiment.Comment: 9 pages, LaTex 2e, no figure

Remarks on Two Gamma Ray Lines from the Inner Galaxy

Monochromatic gamma-ray lines are thought to be the smoking gun signal of the annihilation or decay of dark matter since they do not suffer from deflection or absorption on galactic scales. A recent claim on strong evidence for two gamma-ray lines from the inner galaxy suggests that two-body final states might be one photon plus a Z boson or one photon plus a Higgs boson. In this study, we investigate which final state is more possible by analyzing the energy resolution of the Fermi-LAT. It is concluded that the former case, i.e. one photon plus a Z boson is more plausible than the latter one, i.e. one photon and a Higgs boson since in the latter case the mass of dark matter particle shows tension with a constraint coming from the energy resolution of the Fermi-LAT.Comment: 5 page