pinecone/core-2020-05-10-deduplication huggingface dataset:
D-branes in Standard Model building, Gravity and Cosmology

D-branes are by now an integral part of our toolbox towards understanding
nature. In this review we will describe recent progress in their use to realize
fundamental interactions. The realization of the Standard Model and relevant
physics and problems will be detailed. New ideas on realizing 4-dimensional
gravity use the brane idea in an important way. Such approaches will be
reviewed and compared to the standard paradigm of compactification. Branes can
play a pivotal role both in early- and late-universe cosmology mainly via the
brane-universe paradigm. Brane realizations of various cosmological ideas
(early inflation, sources for dark matter and dark energy, massive gravity etc)
will be also reviewed.Comment: 132 pages, 7 eps figures, LateX, feynmf package. This version will
  appear in Physics Reports. It contains new sections on concrete interesecting
  brane orientifolds, brane-antibrane cosmology and cosmological brane-bulk
  energy exchang
Lectures on the Plane-Wave String/Gauge Theory Duality

These lectures give an introduction to the novel duality relating type IIB
string theory in a maximally supersymmetric plane-wave background to N=4, d=4,
U(N) Super Yang-Mills theory in a particular large N and large R-charge limit
due to Berenstein, Maldacena and Nastase. In the first part of these lectures
the duality is derived from the AdS/CFT correspondence by taking a Penrose
limit of the AdS_5 x S^5 geometry and studying the corresponding double-scaling
limit on the gauge theory side. The resulting free plane-wave superstring is
then quantized in light-cone gauge. On the gauge theory side of the
correspondence the composite Super Yang-Mills operators dual to string
excitations are identified, and it is shown how the string spectrum can be
mapped to the planar scaling dimensions of these operators. In the second part
of these lectures we study the correspondence at the interacting respectively
non-planar level. On the gauge theory side it is demonstrated that the large N
large R-charge limit in question preserves contributions from Feynman graphs of
all genera through the emergence of a new genus counting parameter - in
agreement with the string genus expansion for non-zero g_s. Effective quantum
mechanical tools to compute higher genus contributions to the scaling
dimensions of composite operators are developed and explicitly applied in a
genus one computation. We then turn to the interacting string theory side and
give an elementary introduction into light-cone superstring field theory in a
plane-wave background and point out how the genus one prediction from gauge
theory can be reproduced. Finally, we summarize the present status of the
plane-wave string/gauge theory duality.Comment: 46 pages, Lectures given at the RTN Winter School on Strings,
  Supergravity and Gauge Theory, Turin 7-11 January 2003; v2: references and
  comments in section 6.3 added; v3: references adde
Time-dependent Orbifolds and String Cosmology

In these lectures, we review the physics of time-dependent orbifolds of
string theory, with particular attention to orbifolds of three-dimensional
Minkowski space. We discuss the propagation of free particles in the orbifold
geometries, together with their interactions. We address the issue of stability
of these string vacua and the difficulties in defining a consistent
perturbation theory, pointing to possible solutions. In particular, it is shown
that resumming part of the perturbative expansion gives finite amplitudes.
Finally we discuss the duality of some orbifold models with the physics of
orientifold planes, and we describe cosmological models based on the dynamics
of these orientifolds.Comment: 74 pages, 20 figures. Updated version of lectures at RTN Winter
  School on Strings, Supergravity and Gauge Theory - Torino, January 2003.
  Contains many new results. Minor correction
Representations of the Schrodinger algebra and Appell systems

We investigate the structure of the Schrodinger algebra and its
representations in a Fock space realized in terms of canonical Appell systems.
Generalized coherent states are used in the construction of a Hilbert space of
functions on which certain commuting elements act as self-adjoint operators.
This yields a probabilistic interpretation of these operators as random
variables. An interesting feature is how the structure of the Lie algebra is
reflected in the probability density function. A Leibniz function and
orthogonal basis for the Hilbert space is found. Then Appell systems connected
with certain evolution equations, analogs of the classical heat equation, on
this algebra are computed.Comment: 23 pages, LaTe
Tachyon Condensation for Intersecting Branes at Small and Large Angles

We review the worldsheet analysis for intersecting branes with focus on small
and large angles. For small angles, we review the Yang-Mills fluctuation
analysis in hep-th/0303204 and find an additional family of massless modes.
They are the components of a Goldstone scalar corresponding to the
spontaneously broken U(2)-gauge symmetry. For branes at large angles, we derive
an effective tachyon field theory from BSFT results. We show how the gauge
symmetry of this system implies a mass spectrum which is consistent with the
worldsheet analysis.Comment: 23 pages, 4 figures; references added; one definition clarifie
Field Theory on a Non-commutative Plane: a Non-Perturbative Study

The 2d gauge theory on the lattice is equivalent to the twisted Eguchi-Kawai
model, which we simulated at N ranging from 25 to 515. We observe a clear large
N scaling for the 1- and 2-point function of Wilson loops, as well as the
2-point function of Polyakov lines. The 2-point functions agree with a
universal wave function renormalization. The large N double scaling limit
corresponds to the continuum limit of non-commutative gauge theory, so the
observed large N scaling demonstrates the non-perturbative renormalizability of
this non-commutative field theory. The area law for the Wilson loops holds at
small physical area as in commutative 2d planar gauge theory, but at large
areas we find an oscillating behavior instead. In that regime the phase of the
Wilson loop grows linearly with the area. This agrees with the Aharonov-Bohm
effect in the presence of a constant magnetic field, identified with the
inverse non-commutativity parameter. Next we investigate the 3d \lambda \phi^4
model with two non-commutative coordinates and explore its phase diagram. Our
results agree with a conjecture by Gubser and Sondhi in d=4, who predicted that
the ordered regime splits into a uniform phase and a phase dominated by stripe
patterns. We further present results for the correlators and the dispersion
relation. In non-commutative field theory the Lorentz invariance is explicitly
broken, which leads to a deformation of the dispersion relation. In one loop
perturbation theory this deformation involves an additional infrared divergent
term. Our data agree with this perturbative result
The ultraviolet-finite Hamiltonian approach on the noncommutative
  Minkowski space

This is an exposition of joint work with S. Doplicher, K. Fredenhagen, and G.
Piacitelli on field theory on the noncommutative Minkowski space. The limit of
coinciding points is modified compared to ordinary field theory in a suitable
way which allows for the definition of so-called regularized field monomials as
interaction terms. Employing these in the Hamiltonian formalism results in an
ultraviolet finite S-matrix.Comment: Written version of a talk presented at the 36th International
  Symposium Ahrenshoop on the Theory of Elementary Particles, 26-30 August
  2003, Wernsdorf, Germany. To appear in a special issue of "Fortschritte der
  Physik
Transplanckian Dispersion Relation and Entanglement Entropy of Blackhole

The quantum correction to the entanglement entropy of the event horizon is
plagued by the UV divergence due to the infinitely blue-shifted near horizon
modes. The resolution of this UV divergence provides an excellent window to a
better understanding and control of the quantum gravity effects. We claim that
the key to resolve this UV puzzle is the transplanckian dispersion relation. We
calculate the entanglement entropy using a very general type of transplanckian
dispersion relation such that high energy modes above a certain scale are
cutoff, and show that the entropy is rendered UV finite. We argue that modified
dispersion relation is a generic feature of string theory, and this boundedness
nature of the dispersion relation is a general consequence of the existence of
a minimal distance in string theory.Comment: 7 pages. To appear in the proceedings of 36th International Symposium
  Ahrenshoop on the theory of Elementary Particles: Recent Developments in
  String/M Theory and Field Theory, Berlin, Germany, 26-30 Aug 200
A Gravity Dual of Chiral Symmetry Breaking

We establish a holographic description of chiral symmetry breaking for a
particular confining large N non-supersymmetric gauge theory with matter in the
fundamental representation. The gravity dual of this theory is obtained by
introducing a D7-brane probe into a deformed Anti-de Sitter background found by
Constable and Myers. We numerically compute the \bar\psi\psi condensate and
meson spectrum by solving the equation of motion of the D7-brane probe in this
background. We find a symmetry breaking condensate as well as the associated,
pion-like, Goldstone boson in the limit of small quark mass. The existence of
the condensate ensures that the D7-brane never reaches the naked singularity at
the origin of the deformed AdS space.Comment: Talk given by I.K. at 36th International Symposium Ahrenshoop on the
  Theory of Elementary Particles: Recent Developments in String/M-Theory and
  Field Theory, Berlin, Germany, 26-30 Aug 2003, to appear in Fortsch.Phy
Brane/Flux Interactions in Orientifolds

Combining the benefits of D-branes and background fluxes in string
compactifications opens up the possibility to explore phenomenologically
interesting brane world models with stabilized moduli. However, it is difficult
to determine interaction effects among open strings and fluxes in the effective
action. We derive the full bosonic Lagrangian of a (spontaneously broken) N=4
supersymmetric model with D3-branes and NSNS and RR 3-form fluxes in an
orientifold of type IIB, that, without fluxes, would be T-dual to type I
theory. In the limit where backreaction in form of a warp factor is neglected,
the effective action can be obtained through a procedure that combines
dimensional reduction and T-duality, and it is found to be in agreement with
results from gauged supergravity. This provides evidence for the consistency of
this commonly used approximation scheme.Comment: 8 pages, no figures; Contribution to the proceedings of the 36th
  International Symposium Ahrenshoo
Puzzles for Matrix Models of Chiral Field Theories

We summarize the field-theory/matrix model correspondence for a chiral N=1
model with matter in the adjoint, antisymmetric and conjugate symmetric
representations as well as eight fundamentals to cancel the chiral anomaly. The
associated holomorphic matrix model is consistent only for two fundamental
fields, which requires a modification of the original Dijkgraaf-Vafa
conjecture. The modified correspondence holds in spite of this mismatch.Comment: Contribution to the proceedings of the 36th International Symposium
  Ahrenshoop, Berlin, August 26-30, 2003; 6 Page
Nonlocal Quantum Gravity and the Size of the Universe

Motivated by the conjecture that the cosmological constant problem is solved
by strong quantum effects in the infrared we use the exact flow equation of
Quantum Einstein Gravity to determine the renormalization group behavior of a
class of nonlocal effective actions. They consist of the Einstein-Hilbert term
and a general nonlinear function $F_k(V)$ of the Euclidean spacetime volume
$V$. For the $V + V \ln V$-invariant the renormalization group running
enormously suppresses the value of the renormalized curvature which results
from Planck-size parameters specified at the Planck scale. One obtains very
large, i.e., almost flat universes without finetuning the cosmological
constant. A critical infrared fixed point is found where gravity is scale
invariant.Comment: 6 pages, 1 figure, contribution to the proceedings of the 36th
  International Symposium Ahrenshoop, Berlin, August 26-30, 200
Algebras in tensor categories and coset conformal field theories

The coset construction is the most important tool to construct rational
conformal field theories with known chiral data. For some cosets at small
level, so-called maverick cosets, the familiar analysis using selection and
identification rules breaks down. Intriguingly, this phenomenon is linked to
the existence of exceptional modular invariants. Recent progress in CFT, based
on studying algebras in tensor categories, allows for a universal construction
of the chiral data of coset theories which in particular also applies to
maverick cosets.Comment: 6 pages, 3 figures; Proceeding Ahrenshoop 200
Type IIA on a Compact Calabi-Yau and D=11 Supergravity Uplift of its
  Orientifold

Using the prescription of [1] for defining period integrals in the
Landau-Ginsburg theory for compact Calabi-Yau's, we obtain the Picard-Fuchs
equation and the Meijer basis of solutions for the compact Calabi-Yau
CY_3(3,243) expressed as a degree-24 Fermat hypersurface AFTER resolution of
the orbifold singularities. This is similar in spirit to the method of
obtaining Meijer basis of solutions in [2] for the case wherein one is away
from the orbifold singularities, and one is considering the large-base limit of
the Calabi-Yau. The importance of the method lies in the ease with which one
can consider the large AND small complex structure limits, as well as the
ability to get the "ln"-terms in the periods without having to parametrically
differentiate infinite series. We consider in detail the evaluation of the
monodromy matrix in the large and small complex structure limits. We also
consider the action of the freely acting antiholomorphic involution of [2],[3]
on D=11 supergravity compactified on CY_3(3,243) x S^1 [4] and obtain the
Kaehler potential for the same in the limit of large volume of the Calabi-Yau.
As a by-product, we also give a conjecture for the action of the
orientation-reversing antiholomorphic involution on the periods, given its
action on the cohomology, using a canonical (co)homology basis. Finally, we
also consider showing a null superpotential on the orientifold of type IIA on
CY_3(3,243), having taken care of the orbifold singularities, thereby
completing the argument initiated in [2].Comment: 45 pages, LaTex, 2 ps figures; v3: (Fort. der. Physik) Journal
  versio
On (Orientifold of) type IIA on a Compact Calabi-Yau

We study the gauged sigma model and its mirror Landau-Ginsburg model
corresponding to type IIA on the Fermat degree-24 hypersurface in
WCP^4[1,1,2,8,12] (whose blow-up gives the smooth CY_3(3,243)) away from the
orbifold singularities, and its orientifold by a freely-acting antiholomorphic
involution. We derive the Picard-Fuchs equation obeyed by the period integral
as defined in the work of Cecotti and Hori-Vafa, of the parent N=2 type IIA
theory of Kachru and Vafa. We obtain the Meijer's basis of solutions to the
equation in the large {\it and} small complex structure limits (on the mirror
Landau-Ginsburg side) of the abovementioned Calabi-Yau, and make some remarks
about the monodromy properties associated based on the work of Morrison, at the
same and another MATHEMATICAlly interesting point. Based on a recently shown
N=1 four-dimensional triality (hep-th/0212054) between Heterotic on the
self-mirror Calabi-Yau CY_3(11,11), M theory on (CY_3(3,243) x S^1)/Z_2 and
F-theory on an elliptically fibered CY_4 with the base given by CP^1 x Enriques
surface, we first give a heuristic argument that there can be no superpotential
generated in the orientifold of of CY_3(3,243), and then explicitly verify the
same using mirror symmetry formulation of Hori-Vafa for the abovementioned
hypersurface away from its orbifold singularities. We then discuss briefly the
sigma model and the mirror Landau-Ginsburg model corresponding to the resolved
Calabi-Yau as well.Comment: 31 pages, LaTex, 2 ps figure
Aspects of Stability and Phenomenology in Type IIA Orientifolds with
  Intersecting D6-branes

Intersecting branes have been the subject of string model building for
several years. This work introduces in detail the toroidal and
Z_N-orientifolds, where the main discussion employs the picture of intersecting
D6-branes. The derivation of the R-R and NS-NS tadpole cancellation conditions
in CFT is shown in detail. Various aspects of the massless spectrum are
discussed, involving spacetime anomalies, the generalized Green-Schwarz
mechanism and possible gauge breaking mechanisms. Both N=1 SUSY and non-SUSY
approaches to low energy model building are treated. Firstly, the problem of
complex structure instabilities in toroidal OmegaR-orientifolds is approached
by a Z_3-orbifolded model, including a stable non-SUSY 3-generation
standard-like model. It descends naturally from a flipped SU(5) GUT. Secondly,
supersymmetric models on the Z_4-orbifold are discussed, involving exceptional
3-cycles and the explicit construction of fractional D-branes. A three
generation Pati-Salam model that even can be broken down to a MSSM-like model
is constructed as an example, involving non-flat and non-factorizable branes.
Finally, the possibility that unstable closed and open string moduli could play
the role of the inflaton is being explored. In the closed string sector, the
slow-rolling requirement can only be fulfilled for very specific cases, where
some moduli are frozen and a special choice of coordinates is taken. In the
open string sector, inflation is not possible at all.Comment: 171 pages, PhD thesis, ref. adde
Ricci flows and infinite dimensional algebras

The renormalization group equations of two-dimensional sigma models describe
geometric deformations of their target space when the world-sheet length
changes scale from the ultra-violet to the infra-red. These equations, which
are also known in the mathematics literature as Ricci flows, are analyzed for
the particular case of two-dimensional target spaces, where they are found to
admit a systematic description as Toda system. Their zero curvature formulation
is made possible with the aid of a novel infinite dimensional Lie algebra,
which has anti-symmetric Cartan kernel and exhibits exponential growth. The
general solution is obtained in closed form using Backlund transformations, and
special examples include the sausage model and the decay process of conical
singularities to the plane. Thus, Ricci flows provide a non-linear
generalization of the heat equation in two dimensions with the same dissipative
properties. Various applications to dynamical problems of string theory are
also briefly discussed. Finally, we outline generalizations to higher
dimensional target spaces that exhibit sufficient number of Killing symmetries.Comment: 10 pages, contribution to 36th Ahrenshoop meeting, Berli
Brane-bulk energy exchange and cosmological acceleration

The consequences for the brane cosmological evolution of energy exchange
between the brane and the bulk are analyzed. A rich variety of brane
cosmologies is obtained, depending on the precise mechanism of energy transfer,
the equation of state of brane-matter and the spatial topology. An accelerating
era is generically a feature of the solutions.
  (Prepared for 36th International Symposium Ahrenshoop on the Theory of
Elementary Particles: Recent Developments in String M Theory and Field Theory,
Wernsdorf, Germany, 26-30 Aug 2003.)Comment: 14 pages, 2 figures, Late
Long time scales and eternal black holes

We discuss the various scales determining the temporal behaviour of
correlation functions in the presence of eternal black holes. We point out the
origins of the failure of the semiclassical gravity approximation to respect a
unitarity-based bound suggested by Maldacena. We find that the presence of a
subleading (in the large-N approximation involved) master field does restore
the compliance with one bound but additional configurations are needed to
explain the more detailed expected time dependence of the Poincare recurrences
and their magnitude.Comment: 10 pages, 6 figures. Presented at Johns Hopkins 2003 and Ahrenshoop
  2003 workshop
Comments on the scalar propagator in AdS x S and the BMN plane wave

We discuss the scalar propagator on generic AdS_{d+1} x S^{d'+1} backgrounds.
For the conformally flat situations and masses corresponding to Weyl invariant
actions the propagator is powerlike in the sum of the chordal distances with
respect to AdS_{d+1} and S^{d'+1}. In all other cases the propagator depends on
both chordal distances separately. We discuss the KK mode summation to
construct the propagator in brief. For AdS_5 x S^5 we relate our propagator to
the expression in the BMN plane wave limit and find a geometric interpretation
of the variables occurring in the known explicit construction on the plane
wave.Comment: 7 pages, Fortsch.Phys. style, Talk given at 36th International
  Symposium Ahrenshoop on the Theory of Elementary Particles: Recent
  Developments in String/M- Theory and Field Theory, Wernsdorf, Germany, 26-30
  Aug 200
Higher Spin Gauge Theories in Various Dimensions

Properties of nonlinear higher spin gauge theories of totally symmetric
massless higher spin fields in anti-de Sitter space of any dimension are
discussed with the emphasize on the general aspects of the approach.Comment: LaTeX, 20 pages, Unified version of the talks delivered at
  International Workshop "Supersymmetries and Quantum Symmetries" (SQS'03,
  Dubna, Russia, July 24-29, 2003), 27th Johns Hopkins Workshop (Goteborg,
  Sweden, August 24-26) and 36th International Symposium Ahrenshoop on the
  Theory of Elementary Particles (Berlin, Germany, 26-30 Aug 2003); typos
  corrected, reference adde
Unified Theories from Fuzzy Extra Dimensions

We combine and exploit ideas from Coset Space Dimensional Reduction (CSDR)
methods and Non-commutative Geometry. We consider the dimensional reduction of
gauge theories defined in high dimensions where the compact directions are a
fuzzy space (matrix manifold). In the CSDR one assumes that the form of
space-time is M^D=M^4 x S/R with S/R a homogeneous space. Then a gauge theory
with gauge group G defined on M^D can be dimensionally reduced to M^4 in an
elegant way using the symmetries of S/R, in particular the resulting four
dimensional gauge is a subgroup of G. In the present work we show that one can
apply the CSDR ideas in the case where the compact part of the space-time is a
finite approximation of the homogeneous space S/R, i.e. a fuzzy coset. In
particular we study the fuzzy sphere case.Comment: 6 pages, Invited talk given by G. Zoupanos at the 36th International
  Symposium Ahrenshoop, Wernsdorf, Germany, 26-30 Aug 200
Generalizations of the AdS/CFT correspondence

We consider generalizations of the AdS/CFT correspondence in which probe
branes are embedded in gravity backgrounds dual to either conformal or
confining gauge theories. These correspond to defect conformal field theories
(dCFT) or QCD-like theories with fundamental matter, respectively. Computing
the quark condensate and the meson spectrum for a non-supersymmetric QCD-like
theory from supergravity, we find spontaneous U(1) chiral symmetry breaking as
well as the associated Goldstone boson. For another example at finite
temperature, we observe a phase transition corresponding to a geometrical
transition of the brane embedding. Moreover, starting from the dCFT we discuss
the deconstruction of intersecting M5-branes. The resulting theory corresponds
to two six-dimensional (2,0) superconformal field theories which we show to
have tensionless strings on their four-dimensional intersection. Finally, we
comment on the deconstruction of M-theory from a non-supersymmetric quiver
gauge theory.Comment: Ph.D. Thesis, Humboldt University, Berlin, 130 pages, 38 figures,
  accepted for publication in Fortschritte der Physi