575 research outputs found
String Field Theory from IIB Matrix Model
We derive Schwinger-Dyson equations for the Wilson loops of a type IIB matrix
model. Superstring coordinates are introduced through the construction of the
loop space. We show that the continuum limit of the loop equation reproduces
the light-cone superstring field theory of type IIB superstring in the large-N
limit. We find that the interacting string theory can be obtained in the double
scaling limit as it is expected.Comment: 21 pages, Latex, 1 figur
Hysteresis in Anti-Ferromagnetic Random-Field Ising Model at Zero Temperature
We study hysteresis in anti-ferromagnetic random-field Ising model at zero
temperature. The external field is cycled adiabatically between - and
. Two different distributions of the random-field are considered, (i) a
uniform distribution of width centered at the origin, and (ii) a
Gaussian distribution with average value zero and standard deviation .
In each case the hysteresis loop is determined exactly in one dimension and
compared with numerical simulations of the model
Towards unified theory of gravity
We introduce a new 1-matrix model with arbitrary potential and the
matrix-valued background field. Its partition function is a -function of
KP-hierarchy, subjected to a kind of -constraint. Moreover,
partition function behaves smoothly in the limit of infinitely large matrices.
If the potential is equal to , this partition function becomes a
-function of -reduced KP-hierarchy, obeying a set of -algebra constraints identical to those conjectured in \cite{FKN91} for
double-scaling continuum limit of -matrix model. In the case of
the statement reduces to the early established \cite{MMM91b} relation between
Kontsevich model and the ordinary quantum gravity . Kontsevich model with
generic potential may be considered as interpolation between all the models of
quantum gravity with preserving the property of integrability and
the analogue of string equation.Comment: 67 pages (October 1991
Towards the Theory of Non--Abelian Tensor Fields I
We present a triangulation--independent area--ordering prescription which
naturally generalizes the well known path ordering one. For such a prescription
it is natural that the two--form ``connection'' should carry three ``color''
indices rather than two as it is in the case of the ordinary one--form gauge
connection. To define the prescription in question we have to define how to
{\it exponentiate} a matrix with three indices. The definition uses the fusion
rule structure constants.Comment: 22 pages, 18 figure
On the validity of ADM formulation in 2D quantum gravity
We investigate 2d gravity quantized in the ADM formulation, where only the
loop length is retained as a dynamical variable of the gravitation, in
order to get an intuitive physical insight of the theory. The effective action
of is calculated by adding scalar fields of conformal coupling, and the
problems of the critical dimension and the time development of are
addressed.Comment: 12 page
On Equivalence of Topological and Quantum 2d Gravity
We demonstrate the equivalence of Virasoro constraints imposed on continuum
limit of partition function of Hermitean 1-matrix model and the Ward identities
of Kontsevich's model. Since the first model describes ordinary quantum
gravity, while the second one is supposed to coincide with Witten's topological
gravity, the result provides a strong implication that the two models are
indeed the same.Comment: 14 pages (August 1991
Eigensystem and Full Character Formula of the W_{1+infinity} Algebra with c=1
By using the free field realizations, we analyze the representation theory of
the W_{1+infinity} algebra with c=1. The eigenvectors for the Cartan subalgebra
of W_{1+infinity} are parametrized by the Young diagrams, and explicitly
written down by W_{1+infinity} generators. Moreover, their eigenvalues and full
character formula are also obtained.Comment: 12 pages, YITP/K-1049, SULDP-1993-1, RIMS-959, Plain TEX, ( New
references
Higher spin constraints and the super algebra in the super eigenvalue model
We show that the partition function of the super eigenvalue model satisfies
an infinite set of constraints with even spins . These
constraints are associated with half of the bosonic generators of the super
algebra. The
simplest constraint is shown to be reducible to the super Virasoro
constraints, previously used to construct the model. All results hold for
finite .Comment: 14 pages, latex, no figure
Optical detection of spin transport in non-magnetic metals
We determine the dynamic magnetization induced in non-magnetic metal wedges
composed of silver, copper and platinum by means of Brillouin light scattering
(BLS) microscopy. The magnetization is transferred from a ferromagnetic
Ni80Fe20 layer to the metal wedge via the spin pumping effect. The spin pumping
efficiency can be controlled by adding an insulating but transparent interlayer
between the magnetic and non-magnetic layer. By comparing the experimental
results to a dynamical macroscopic spin-transport model we determine the
transverse relaxation time of the pumped spin current which is much smaller
than the longitudinal relaxation time
Remarks on hard Lefschetz conjectures on Chow groups
We propose two conjectures of Hard Lefschetz type on Chow groups and prove
them for some special cases. For abelian varieties, we shall show they are
equivalent to well-known conjectures of Beauville and Murre.Comment: to appear in Sciences in China, Ser. A Mathematic
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