276 research outputs found

### Holography Principle and Topology Change in String Theory

D-instantons of Type IIB string theory are Ramond-Ramond counterpart of
Giddings-Strominger wormholes connecting two asymptotic regions of spacetime.
Such wormholes, according to Coleman, might lead to spacetime topology change,
third-quantized baby universes and probabilistic determination of fundamental
coupling parameters. Utilizing correspondence between AdS5 x M5 Type IIB
supergravity and d=4 super Yang-Mills theory, we point out that topology change
and sum over topologies not only take place in string theory but also are
required for consistency with holography. Nevertheless, the effects of
D-instanton wormholes remain completely deterministic, in sharp contrast to
Coleman's scenario.Comment: Latex, one figure, 10 pages, v2. references corrected, v3. version to
appear in Classical and Quantum Gravit

### Collective Coordinate Quantization of Dirichlet Branes

Collective coordinate quantization of Dirichlet branes is discussed.
Utilizing Polchinski's combinatoric rule, semiclassical D-brane wave functional
is given in proper-time formalism. D-brane equation of motion is then
identified with renormalization group equation of defining Dirichlet open
string theory. Quantum mechanical size of macroscopically charged D-brane is
illustrated and striking difference from ordinary field theory BPS particle is
emphasized.Comment: 16 pages, ReVTe

### Exact Answers to Approximate Questions: Noncommutative Dipoles, Open Wilson Lines, and UV-IR Duality

In this lecture, I put forward conjectures asserting that, in all
noncommutative field theories, (1) open Wilson lines and their descendants
constitute a complete set of interpolating operators of `noncommutative
dipoles', obeying dipole relation, (2) infrared dynamics of the noncommutative
dipoles is dual to ultraviolet dynamics of the elementary noncommutative
fields, and (3) open string field theory is a sort of noncommutative field
theory, whose open Wilson lines are interpolating operators for closed strings.
I substantiate these conjectures by various intuitive arguments and explicit
computations of one- and two-loop Feynman diagrammatics.Comment: short lecture at 2001 Les Houches summer schoo

### M(atrix) Theory on the Negative Light-Front

M(atrix) theory defines light-front description of M-theory boosted along
positive direction of eleventh, M-coordinate. Rank of M(atrix) gauge group is
directly related to M-momentum $P_{11} = N / R_{11}$ or, equivalently, to total
number of D0-partons. Alternatively, M-theory may be boosted along opposite
direction of M-coordinate, for which the theory consists only of anti-D0
partons. In M(atrix) theory description, we interpret this as analytic
continuation of dimension of the gauge group: $U(-N) \sim U(N)$, $SO(-2N) \sim
USp(2N)$ and $USp(-2N) \sim SO(2N)$. We check these reciprocity relations
explicitly for uncompactified, heterotic, and CHL M(atrix) theories as well as
effective M(atrix) gauge theories of $T_5/Z_2$ and $T_9/Z_2$ compactifications.
In all cases, we show that absence of parity, gauge and supersymmetry anomalies
require introduction of a twisted sector with negative numbers of matter
multiplets. They are interpreted as massless open string excitations connected
to anti-D-brane background.Comment: Latex, no figur

### Recent Progress in String Inflationary Cosmology

Super--inflation driven by dilaton/moduli kinetic energy is naturally
realized in compactified string theory. Discussed are selected topics of recent
development in string inflationary cosmology: kinematics of super-inflation,
graceful exit triggered by quantum back reaction, and clasical and quantum
power spectra of density and metric perturbations.Comment: 5 pages, latex, jkas2.sty file included, typos corrected. Invited
talk at 7th Asian-Pacific Regional Meeting of the International Astronomical
Union, August 19 - 23, 1996. To be published in the proceedin

### String Theory on Thin Semiconductors: Holographic Realization of Fermi Points and Surfaces

I make a novel contact between string theory and degenerate fermion dynamics
in thin semiconductors. Utilizing AdS/CFT correspondence in string theory and
tunability of coupling parameters in condensed matter systems, I focus on the
possibilities testing string theory from tabletop experiments. I first discuss
the observation that stability of Fermi surface is classifiable according to
K-theory. I then elaborate two concrete realization of Fermi surfaces of zero
and two dimensions. Both are realized by complex of D3-branes and D7-branes of
relative codimension 6 and 4, respectively. The setup with Fermi point models
gauge dynamics of multiply stacked graphenes at half-filling. I show that
string theory predicts dynamical generation of mass gap and metal-insulator
quantum phase transition at zero temperature. I emphasize that conformally
invariant gauge theory dynamics of the setup plays a crucial role, leading to
novel conformal phase transition. The setup with Fermi surface is in
collaboration with Dongsu Bak and is based on charged black hole and models
relativistic Fermi liquid. We find positive evidence for this identification
from both equilibrium thermodynamics at or near zero temperature and
out-of-equilibrium linear response and transport properties. I argue that
fluctuation of black hole horizon provides holographic realization consistent
with Fermi liquid for thermodynamics and interesting departures therefrom in
transport properties.Comment: Proceedings of "30 Years of Mathematical Methods in High Energy
Physics", March 17 - 19, 2008. Also covers talks given at "Strings 2007" June
24-30, 2007 (Madrid, Spain) and "Strong Coupling: From Lattice to AdS/CFT"
June 4- 6, 2008 (GGI, Florence, Italy). Charged AdS black hole as Fermi liqud
was done in collaboration with Dongsu Ba

### Effective Field Theory for Diffractive QCD Processes

An effective field theory describing the QCD diffraction scattering is
constructed. The constituent quarks interacting with multiperi- pheral gluons
and Goldstone bosons are described by impact- parameter two-dimensional sigma
models for the color and the flavor degrees of freedom. The elastic scattering
amplitude is then shown to factorize into the hard and the soft pomeron
contributions (talk at 5th Blois Workshop on Elastic and Diffractive Scattering
Workshop, June 8 - 12, 1993, Providence RI USA)Comment: 8 Page

### Gravitating M(atrix) Q-Balls

Q-ball configuration that represents oscillating or spinning closed membrane
is constructed via M(atrix) theory. Upon gravitational collapse Q-balls are
expected to form Schwarzschild black holes. For quasi-static spherical
membrane, we probe spacetime geometry induced by monopole moment via D0-parton
scattering off the Q-ball. We find a complete agreement with long distance
potential calculated using eleven-dimensional supergravity. Generalizing to
heterotic M(atrix) theory, we also construct Q-ball configurations of real
projective and disk membranes. The latter Q-ball configuration arises as
twisted sector of heterotic M(atrix) theory, hence, are expected to form a
charged black hole after gravitational collapse.Comment: Latex, no figure

### Rolling Tachyon with Electric and Magnetic Fields -- T-duality approach -----

We study the decay of unstable D$p$-branes when the world-volume gauge field
is turned on. We obtain the relevant Dp-brane boundary state with electric and
magnetic fields by boosting and rotating the rolling tachyon boundary state of
a D(p-1)-brane and then T-dualizing along one of the transverse directions. A
simple recipe to turn on the gauge fields in the boundary state is given. We
find that the effect of the electric field is to parametrically enhance
coupling of closed string oscillation modes along the electric field direction
and provide an intuitive understanding of the result in the T-dualized picture.
We also analyze the system by using the effective field theory and compare the
result with the boundary state approach.Comment: Latex, 6.eps figs, v2:affiliation & acknowledgement adde

### 3 Into 2 Doesn't Go: (almost) chiral gauge theory on the lattice

Kaplan recently proposed a novel lattice chiral gauge theory in which the
bare theory is defined on $(2n+1)$-dimensions, but the continuum theory emerges
in $2n$-dimensions. We explore whether the resulting theory reproduces all the
features of continuum chiral gauge theory in the case of two-dimensional axial
Schwinger model. We find that one can arrange for the two-dimensional
perturbation expansion to be reproduced successfully. However, the theory fails
to reproduce the 2-dimensional fermion nonconservation.Comment: 13 pages (no figures

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