pinecone/core-2020-05-10-deduplication huggingface dataset:
Abelian and Non-abelian D-brane Effective Actions

In this Ph.D. thesis we review and elaborate on a method to find the D-brane
effective action, based on BPS equations. Firstly, both for the Yang-Mills
action and the Born-Infeld action it is shown that these configurations are
indeed BPS, i.e. solutions to these equations saturate a Bogomolny bound and
leave some supersymmetry unbroken. Next, we use the BPS equations as a tool to
construct the D-brane effective action and require that (a deformation of)
these equations should still imply the equations of motion in more general
cases. In the abelian case we managed to calculate all order in $\alpha'$
four-derivative corrections to the effective action and the BPS equations while
in the non-abelian case we obtained the effective action up to order
$\alpha'^4$. Furthermore, we discuss a check based on the spectrum of strings
stretching between intersecting branes. Finally, this Ph.D. thesis also
discusses the construction of a boundary superspace which is the first step to
use the method of Weyl invariance in N=2 superspace in order to again construct
the D-brane effective action. A more detailed summary of each chapter can be
found in the introduction.Comment: Ph.D. thesis, Vrije Universiteit Brussel, 168 pages, 10 figures,
  LaTeX, v2: clarification added to 3.3.2, references added, v3: metadata
  change: broken link remove
Superstring Orientifolds with Torsion: O5 Orientifolds of Torus
  Fibrations and their Massless Spectra

Using a ``Superstrings with Torsion'' type description, we study a class of
IIB orientifolds in which spacefilling O5 planes and D5 branes wrap the T^2
fiber in a warped modification of the product of 4D Minkowski space and a T^2
fibration. For the case that the base is T^4, we provide examples that preserve
4D N = 1, 2, and 3 supersymmetry, both with internal RR flux, and with a
combination of internal RR and NS flux. In these examples, the internal
geometries admit integrable complex structure; however, the almost complex
structure selected by the supersymmetry conditions is nonintegrable in the case
that there is NS flux. We indicate explicitly the massless spectrum of gauge
fields and moduli in each example. In a previous investigation, this class of
orientifolds was studied using T-duality. Here, we extend the previous
analysis, first by providing an intrinsic description that does not rely on
duality, and then by elaborating on details of the T-duality map, which we use
to check our results.Comment: 110 pages; uses harvmac.tex, amssym.tex; v2: minor corrections,
  references adde
Quantum information and general relativity

The Einstein-Podolsky-Rosen paradox (1935) is reexamined in the light of
Shannon's information theory (1948). The EPR argument did not take into account
that the observers' information was localized, like any other physical object.
General relativity introduces new problems: there are horizons which act as
one-way membranes for the propagation of quantum information, in particular
black holes which act like sinks.Comment: to be published in Fortschritte der Physik (proceedings of the
  meeting "Quantum Optics for Quantum Information Processing" Rome, 7-8 May
  200
Atom Interferometry in a Vertical Optical Lattice

We have studied the interference of degenerate quantum gases in a vertical
optical lattice. The coherence of the atoms leads to an interference pattern
when the atoms are released from the lattice. This has been shown for a
Bose-Einstein condensate in early experiments. Here we demonstrate that also
for fermions an interference pattern can be observed provided that the momentum
distribution is smaller then the recoil momentum of the lattice. Special
attention is given to the role of interactions which wash out the interference
pattern for a condensate but do not affect a spin polarized Fermi gas, where
collisions at ultra cold temperatures are forbidden. Comparing the interference
of the two quantum gases we find a clear superiority of fermions for trapped
atom interferometry.Comment: 10 pages, 5 figure
Electric/Magnetic Deformations of S^3 and AdS_3, and Geometric Cosets

We analyze asymmetric marginal deformations of SU(2)_k and SL(2,R)_k WZW
models. These appear in heterotic string backgrounds with non-vanishing
Neveu--Schwarz three-forms plus electric or magnetic fields, depending on
whether the deformation is elliptic, hyperbolic or parabolic. Asymmetric
deformations create new families of exact string vacua. The geometries which
are generated in this way, deformed S^3 or AdS_3, include in particular
geometric cosets such as S^2, AdS_2 or H_2. Hence, the latter are consistent,
exact conformal sigma models, with electric or magnetic backgrounds. We discuss
various geometric and symmetry properties of the deformations at hand as well
as their spectra and partition functions, with special attention to the
supersymmetric AdS_2 x S^2 background. We also comment on potential holographic
applications.Comment: 38 pages, Added References. Aesthetic retouching
Complete Correlation, Detection loophole and Bell's Theorem

Two new formulations of Bell's theorem are given here. First, we consider a
definite set of two entangled photons with only two polarization directions,
for which Bell's locality assumption is violated for the case of perfect
correlation. Then, using a different approach, we prove an efficient Bell-type
inequality which is violated by some quantum mechanical predictions,
independent of the efficiency factors.Comment: 15 pages, 2 tables, no figure. Last version, to appear in
  Fortschritte der Physi
M-theory and Gauged Supergravities

We present a pedagogical discussion of the emergence of gauged supergravities
from M-theory. First, a review of maximal supergravity and its global
symmetries and supersymmetric solutions is given. Next, different procedures of
dimensional reduction are explained: reductions over a torus, a group manifold
and a coset manifold and reductions with a twist. Emphasis is placed on the
consistency of the truncations, the resulting gaugings and the possibility to
generate field equations without an action.
  Using these techniques, we construct a number of gauged maximal
supergravities in diverse dimensions with a string or M-theory origin. One
class consists of the CSO gaugings, which comprise the analytic continuations
and group contractions of SO(n) gaugings. We construct the corresponding
half-supersymmetric domain walls and discuss their uplift to D- and M-brane
distributions. Furthermore, a number of gauged maximal supergravities are
constructed that do not have an action.Comment: 144 pages, 12 figures, 16 tables. Based on Ph.D. thesis, to be
  submitted to Fortschritte der Physik. v2: references adde
Massive Tensor Multiplets in N=1 Supersymmetry

We derive the action for a massive tensor multiplet coupled to chiral and
vector multiplets as it can appear in orientifold compactifications of type IIB
string theory.We compute the potential of the theory and show its consistency
with the corresponding Kaluza-Klein reduction of N=1 orientifold
compactifications. The potential contains an explicit mass term for the scalar
in the tensor multiplet which does not arise from eliminating an auxiliary
field. A dual action with an additional massive vector multiplet is derived at
the level of superfields.Comment: 14 pages, Late
Flux Vacua Statistics for Two-Parameter Calabi-Yau's

We study the number of flux vacua for type IIB string theory on an
orientifold of the Calabi-Yau expressed as a hypersurface in WCP^4[1,1,2,2,6]
by evaluating a suitable integral over the complex-structure moduli space as
per the conjecture of Douglas and Ashok. We show that away from the singular
conifold locus, one gets a power law, and that the (neighborhood) of the
conifold locus indeed acts as an attractor in the (complex structure) moduli
space. We also study (non)supersymmetric solutions near the conifold locus.In
the process, we evaluate the periods near the conifold locus. We also study
(non)supersymmetric solutions near the conifold locus, and show that
supersymmetric solutions near the conifold locus do not support fluxes.Comment: 17 pages, LaTex; Part of AN's BTech
  end-of-undergraduate-freshman(=first)-year summer project at IIT Roorkee; v3:
  a reference and clarifying text and equations added, a numerical error
  correcte
Higher Spins and Stringy AdS5xS5

In this lecture I review recent work on higher spin holography. After a
notational flash on the AdS/CFT correspondence, I will discuss HS symmetry
enhancement and derive the spectrum of perturbative type IIB superstring
excitations on AdS5 in this limit. I will then successfully compare it with the
free N=4 SYM spectrum obtained by means of Polya theory. Decomposing the
spectrum in HS multiplets, I will eventually sketch how ``La Grande Bouffe''
can be formulated a` la Stueckelberg.Comment: 40 pages, Latex, uses youngtab.sty. Lecture delivered at the RTN
  Workshop "The quantum structure of spacetime and the geometric nature of
  fundamental interactions", EXT Workshop "Fundamental Interactions and the
  Structure of Spacetime" in Kolymbari, Crete, 5-10 September 200
Recent Progress in Intersecting D-brane Models

The aim of this article is to review some recent progress in the field of
intersecting D-brane models. This includes the construction of chiral,
semi-realistic flux compactifications, the systematic study of Gepner model
orientifolds, the computation of various terms in the low energy effective
action and the investigation of the statistics of solutions to the tadpole
cancellation conditions.Comment: 13 pages, 1 figure, contribution to the proceedings of the 37.
  Symposium Ahrenshoop, 23-27 August 2004, Wernsdorf, Germany, v3: more refs.
  adde
The SU(2) sector in AdS/CFT

In the large N limit of N=4 Super Yang-Mills, the mixing under dilatations of
the SU(2) sector, single trace operators composed of L complex scalar fields of
two types, is closed to all orders in perturbation theory. By relying on the
AdS/CFT correspondence, and by examining the currents for semiclassical
strings, we present evidence which implies that there are small mixings that
contradict the closure of the SU(2) sector in the strong coupling limit. These
mixings first appear to second order in the \lambda/L^2 expansion.Comment: 17 Pages, no figures, to appear in the proceedings of the RTN
  workshop, Kolymbari, Crete, September 2004; v2 refs added, footnote change
Quantum Strings and Bethe Equations

I briefly review the recently proposed construction of the Bethe ansatz which
diagonalizes the Hamiltonian for quantum strings on AdS_5\times S^5 at large
tension and restricted to the large charge states from a closed su(2)
subsector.Comment: Latex, 6 pages, Talk delivered at RTN Workshop on the Quantum
  Structure of Space-time and the Geometric Nature of Fundamental Interactions
  and EXT Workshop on Fundamental Interactions and the Structure of Spacetime,
  Kolymbari, Crete, Greece, 5-10 Sep 200
Spin Chain for Quantum Strings

We review and compare the integrable structures in N=4 gauge theory and
string theory on AdS5xS5. Recently, Bethe ansaetze for gauge theory/weak
coupling and string theory/strong coupling were proposed to describe scaling
dimensions in the su(2) subsector. Here we investigate the Bethe equations for
quantum string theory, naively extrapolated to weak coupling. Excitingly, we
find a spin chain Hamiltonian similar, but not equal, to the gauge theory
dilatation operator.Comment: 10 pages, Contribution to RTN and EXT Workshop, Kolymbari, Crete,
  Greece, 5-10 September 2004, v2: numerical comparision with spinning strings
  added, coefficient of H4 in Tab. 3 correcte
Stabilization of moduli by fluxes

In order to lift the continuous moduli space of string vacua, non-trivial
fluxes may be the essential input. In this talk I summarize aspects of two
approaches to compactifications in the presence of fluxes: (i) generalized
Scherk-Schwarz reductions and gauged supergravity and (ii) the description of
flux-deformed geometries in terms of G-structures and intrinsic torsion.Comment: 22 pages, added refs., to appear in proceedings of: ``Strings and
  Cosmology'', (Texas A&M University, March 2004) and the RTN workshop: ``The
  quantum structure of space-time and ...'' (Kolymbari, Crete, September 2004
Konishi Anomalies and N=1 Curves

We present a brief summary of exact results on the non-perturbative effective
superpotential of N=1 supersymmetric gauge theories based on generalized
Konishi anomaly equations. In particular we consider theories with classical
gauge groups and chiral matter in two-index tensor representations. All these
theories can be embedded into theories with unitary gauge group and adjoint
matter. This embedding can be used to derive expressions for the exact
non-perturbative superpotential in terms of the 1/N expansion of the free
energy of the related matrix models.Comment: 6 pages, contribution to the proceedings of the 37th International
  Symposium Ahrenshoop on the Theory of Elementary Particles; v2: References
  adde
Noncommutative Sine-Gordon Model

As I briefly review, the sine-Gordon model may be obtained by dimensional and
algebraic reduction from 2+2 dimensional self-dual U(2) Yang-Mills through a
2+1 dimensional integrable U(2) sigma model. I argue that the noncommutative
(Moyal) deformation of this procedure should relax the algebraic reduction from
U(2)->U(1) to U(2)->U(1)xU(1). The result are novel noncommutative sine-Gordon
equations for a pair of scalar fields. The dressing method is outlined for
constructing its multi-soliton solutions. Finally, I look at tree-level
amplitudes to demonstrate that this model possesses a factorizable and causal
S-matrix in spite of its time-space noncommutativity.Comment: 6 pages, 4 figures; talk at the XIIIth International Colloquium
  Integrable Systems and Quantum Groups in Prague 17-19 June 2004, and at the
  37th International Symposium Ahrenshoop on the Theory of Elementary Particles
  in Berlin-Schm"ockwitz 23-27 August 200
New aspects of N=2 theories

We review some recent observations in theories with eight supercharges. We
point out that such theories can be generalized by starting from the equations
of motion rather than from an action. We show that vector multiplets
constructed in such a way can have more general Fayet-Iliopoulos terms and that
the scalar fields of hypermultiplets can be coordinate functions on more
general target spaces. Although our discussion holds in five dimensions, the
results can easily be extended to other dimensions.Comment: 8 pages; contribution to the proceedings of the EC-RTN Workshop 'The
  quantum structure of spacetime and the geometric nature of fundamental
  interactions', Kolymbari, Crete, 5-10/9/200
Solving Virasoro Constraints in Matrix Models

This is a brief review of recent progress in constructing solutions to the
matrix model Virasoro equations. These equations are parameterized by a degree
n polynomial W_n(x), and the general solution is labeled by an arbitrary
function of n-1 coefficients of the polynomial. We also discuss in this general
framework a special class of (multi-cut) solutions recently studied in the
context of \cal N=1 supersymmetric gauge theories.Comment: 9 pages, LaTeX, contribution to the 37th International Symposium
  Ahrenshoop on the Theory of Elementary Particle
Classification and a toolbox for orientifold models

We provide the general tadpole conditions for a class of supersymmetric
orientifold models by studing the general properties of the elements included
in the orientifold group. In this talk, we concentrate on orientifold models of
the type $T^6/Z_M\times Z_N$.Comment: 8 pages, 1 figure, Latex2e. Proceedings of RTN Workshop on the
  Quantum Structure of Space-time and the Geometric Nature of Fundamental
  Interactions and EXT Workshop on Fundamental Interactions and the Structure
  of Spacetime, Kolymbari, Crete, Greece, 5-10 Sep 200
Supersymmetry and flavor in a sugra dual of N=1 Yang-Mills

Some field theory aspects can be addressed holographically by introducing
D-branes in the string theory duals. In this work, we study this issue in the
framework of a dual of N=1 YM, the so-called Maldacena-Nunez model. Some
supersymmetric embeddings for D5-brane probes are found and they are
interpreted as the addition of fundamental flavors to the gauge theory. This
allows to give a dual description of some known aspects of N=1 SQCD and to
compute a mass spectrum of mesons.Comment: 7 pages, 2 figures. Contribution to the proceedings of the 37
  Symposium Ahrenshoop, 23-27 August 2004, Germany; reference adde
Progress on Holographic Three-Point Functions

The recently developed gauge-invariant formalism for the treatment of
fluctuations in holographic renormalization group (RG) flows overcomes most of
the previously encountered technical difficulties. I summarize the formalism
and present its application to the GPPZ flow, where scattering amplitudes
between glueball states have been calculated and a set of selection rules been
found.Comment: talk given at the RTN workshop "The quantum structure of space-time
  and the geometric nature of fundamental interactions", Kolymbari, September
  5-10, 200
Catching the phantom: the MSSM on the Z6-orientifold

These lecture notes give a short introduction of the derivation of the
supersymmetric standard model on the Z6-orientifold as published in
hep-th/0404055. Untwisted and twisted cycles are constructed and one specific
model is discussed in more detail.Comment: To appear in the proceedings of RTN Workshop on the Quantum Structure
  of Space-time and the Geometric Nature of Fundamental Interactions and EXT
  Workshop on Fundamental Interactions and the Structure of Spacetime,
  Kolymbari, Crete, Greece, 5-10 Sep 200
Non-extremal instantons and wormholes in string theory

We construct the most general non-extremal spherically symmetric instanton
solution of a gravity-dilaton-axion system with $SL(2,R)$ symmetry, for
arbitrary euclidean spacetime dimension $D\geq 3$. A subclass of these
solutions describe completely regular wormhole geometries, whose size is
determined by an invariant combination of the $SL(2,R)$ charges.
  Our results can be applied to four-dimensional effective actions of type II
strings compactified on a Calabi-Yau manifold, and in particular to the
universal hypermultiplet coupled to gravity. We show that these models contain
regular wormhole solutions, supported by regular dilaton and RR scalar fields
of the universal hypermultiplet.Comment: 10 pages, to appear in the proceedings of the RTN2004 workshop,
  Kolymbari, Crete, 5-10 September, Greec
Geometric Transitions, Non-Kahler Geometries and String Vacua

We summarize an explicit construction of a duality cycle for geometric
transitions in type II and heterotic theories. We emphasize that the manifolds
with torsion constructed with this duality cycle are crucial for understanding
different phenomena appearing in effective field theories.Comment: Contribution to the Proceedings of Snowbird Conference,June 2004; the
  37th International Symposium Ahrenshoop, Berlin, August, 2004 and DPF
  Meeting, Riverside, August 2004, 7 Pages;v3:one small correctio
Semiclassical Bethe Ansatz and AdS/CFT

The Bethe ansatz can be used to compute anomalous dimensions in N=4 SYM
theory. The classical solutions of the sigma-model on AdS(5)xS(5) can also be
parameterized by an integral equation of Bethe type. In this note the
relationship between the two Bethe ansaetze is reviewed following
hep-th/0402207.Comment: 13 pages, Based on talks at Strings04, Paris, 28.06-02.07; 37th
  Symposium Ahrenshoop, Berlin, 23.08-27.08 and Integrable Models and
  Applications, Sozopol, 31.08-04.09; v2: misprints in (38) and (61) corrected;
  v3: misprints in (3) and (11) corrected; v4: misprint in (20) correcte
Complex curves and non-perturbative effects in c=1 string theory

We investigate a complex curve in the $c=1$ string theory which provides a
geometric interpretation for different kinds of D-branes. The curve is
constructed for a theory perturbed by a tachyon potential using its matrix
model formulation. The perturbation removes the degeneracy of the non-perturbed
curve and allows to identify its singularities with ZZ branes. Also, using the
constructed curve, we find non-perturbative corrections to the free energy and
elucidate their CFT origin.Comment: 8 pages, Contribution to the proceedings of RTN Workshop, Kolymbari,
  Crete, Greece, 5-10 September 200
The symmetric branes of the H4 WZW model

We review the solution of the boundary CFTs that describe the symmetric
branes in the Nappi-Witten gravitational wave, namely D2 and S1 branes. The D2
branes are the twisted branes of the model while the S1 branes are the Cardy
branes. We present in both cases the bulk-boundary couplings and the boundary
three-point couplings and discuss the relation with branes in AdS3 and in S3.
We also discuss the analogy between the open string couplings in the H4 model
and the couplings for magnetized and intersecting branes.Comment: 11 pages, to appear in the proceedings of the RTN Workshop,
  Kolymbari, Greece, 5-10 September 200
Removal of closed time-like curves by supertube domain walls

We discuss how closed time-like curves can be eliminated from certain
supergravity backgrounds by inclusion of domain-walls made of supertubes.
Special emphasis is given to the mechanism by which the supertubes spread into
domain walls, which is similar to the enhanceon mechanism. Lecture notes from
my talk at the RTN meeting in Kolymbari, Crete, September 2004.Comment: 5 pages, uses w-art.cls. Lecture notes from the RTN Workshop on the
  Quantum Structure of Spacetime and the Geometric Nature of Fundamental
  Interactions, Kolymbari, Crete, Sep 200
On the Thermodynamics of Goedel Black Holes

After a brief review of Goedel-type universes in string theory, we discuss
some intriguing properties of black holes immersed in such backgrounds. Among
these are the upper bound on the entropy that points towards a
finite-dimensional Hilbert space of a holographically dual theory, and the
minimum black hole temperature that is reminiscent of the Hawking-Page
transition. Furthermore, we discuss several difficulties that are encountered
when one tries to formulate a consistent thermodynamics of Goedel black holes,
and point out how they may be circumvented.Comment: 7 pages, 2 figures, uses w-art.cls. Talk given by D. K. at the RTN
  Workshop on the Quantum Structure of Spacetime and the Geometric Nature of
  Fundamental Interactions and EXT Workshop on Fundamental Interactions and the
  Structure of Spacetime, Kolymbari, Crete, Greece, 5-10 Sep 2004. To be
  published in Fortsch.Phy
Fluxes and gaugings: N = 1 effective superpotentials

We illustrate the correspondence between the N=1 superstring
compactifications with fluxes, the N=4 gauged supergravities and the
superpotential and K\"ahler potential of the effective N=1 supergravity in four
dimensions. In particular we derive, in the presence of general fluxes, the
effective N=1 supergravity theory associated to the type IIA orientifolds with
D6 branes, compactified on $T^6/(Z_2 \times Z_2)$. We construct explicit
examples with different features: in particular, new IIA no-scale models, new
models with cosmological interest and a model which admits a supersymmetric
AdS$_4$ vacuum with all seven main moduli ($S, T_A, U_A,A=1,2,3$) stabilized.Comment: 14 page
Semiclassical strings on confining backgrounds

This paper discusses some results on semiclassical string configurations
lying in the IR sector of supergravity backgrounds dual to confining gauge
theories. On the gauge theory side, the string states we analyse correspond to
Wilson loops, glueballs and KK-hadrons. The 1-loop correction to the classical
energy is never subleading, but can be viewed as a coupling dependent rescaling
of the dimensionful parameters of the theory.Comment: 11 pages, contribution for the proceedings of the RTN Workshop,
  Kolymbari, Crete, Greece, 5-10 Sep 200