38 research outputs found
Building Blocks of Physical States in a Non-Critical 3-Brane on R*S^3
The physical states in a world-volume model of a non-critical 3-brane are
systematically constructed using techniques of four-dimensional conformal field
theories on R*S^3 developed recently. Invariant combinations of creation modes
under a special conformal transformation provide building blocks of physical
states. Any state can be created by acting with such building blocks on a
conformally invariant vacuum in an invariant way under the other conformal
charges: the Hamiltonian and rotation generators on S^3. We explicitly
construct building blocks for scalar, vector and gravitational fields, and
classify them as finite types.Comment: 56 page
Phase Structure of Four-dimensional Simplicial Quantum Gravity with a U(1) Gauge Field
The phase structure of four-dimensional simplicial quantum gravity coupled to
U(1) gauge fields has been studied using Monte-Carlo simulations. The smooth
phase is found in the intermediate region between the crumpled phase and the
branched polymer phase. This new phase has a negative string susceptibility
exponent, even if the number of vector fields (Nv) is 1. The phase transition
between the crumpled phase and the smooth phase has been studied by a finite
size scaling method. From the numerical results, we expect that this model
(coupled to one gauge field) has a higher order phase transition than first
order, which means the possibility to take the continuum limit at the critical
point. Furthermore, we consider a modification of the balls-in-boxes model for
a clear understanding of the relation between the numerical results and the
analytical one.Comment: 18 pages, latex, 6 figures, uses psfig.st
Geometry of 4d Simplicial Quantum Gravity with a U(1) Gauge Field
The geometry of 4D simplicial quantum gravity with a U(1) gauge field is
studied numerically. The phase diagram shows a continuous transition when
gravity is coupled with a U(1) gauge field. At the critical point measurements
of the curvature distribution of S^4 space shows an inflated geometry with
homogeneous and symmetric nature. Also, by choosing a 4-simplex and fixing the
scalar curvature geometry of the space is measured.Comment: 3 pages, 2 eps figure. Talked at Lattice 2000 (Gravity
Grand-Canonical simulation of 4D simplicial quantum gravity
A thorough numerical examination for the field theory of 4D quantum gravity
(QG) with a special emphasis on the conformal mode dependence has been studied.
More clearly than before, we obtain the string susceptibility exponent of the
partition function by using the Grand-Canonical Monte-Carlo method. Taking
thorough care of the update method, the simulation is made for 4D Euclidean
simplicial manifold coupled to scalar fields and U(1) gauge fields.
The numerical results suggest that 4D simplicial quantum gravity (SQG) can be
reached to the continuum theory of 4D QG. We discuss the significant property
of 4D SQG.Comment: 3 pages, 2 figures, LaTeX, Lattice2002(Gravity
Phase Transition of 4D Simplicial Quantum Gravity with U(1) Gauge Field
The phase transition of 4D simplicial quantum gravity coupled to U(1) gauge
fields is studied using Monte-Carlo simulations. The phase transition of the
dynamical triangulation model with vector field () is smooth as
compared with the pure gravity(). The node susceptibility () is
studied in the finite size scaling method. At the critical point, the node
distribution has a sharp peak in contrast to the double peak in the pure
gravity. From the numerical results, we expect that 4D simplicial quantum
gravity with U(1) vector fields has higher order phase transition than 1st
order, which means the possibility to take the continuum limit at the critical
point.Comment: 3 pages, latex, 3 eps figures, uses espcrc2.sty. Talk presented at
LATTICE99(gravity
CMB Anisotropies Reveal Quantized Gravity
A novel primordial spectrum with a dynamical scale of quantum gravity origin
is proposed to explain the sharp fall off of the angular power spectra at low
multipoles in the COBE and WMAP observations. The spectrum is derived from
quantum fluctuations of the scalar curvature in a renormalizable model of
induced gravity. This model describes the very early universe by the conformal
field fluctuating about an inflationary background with the expansion time
constant of order of the Planck mass.Comment: 12 pages, 2 figure