Members of the group are actively pursuing research in the following areas of Field Theory, String Theory and Cosmology
 Cosmology, IR quantum gravity and inflation
 String Theory
 New ideas in Early Universe cosmology from strings/branes
 IR modifications of gravity and Dark energy.
 String theory and its implications for Beyond the Standard Model Physics
 AdSCFT correspondence and applications to the physics of QCD
 AdSCFT correspondence and applications to the physics of condensed Matter
 HigherSpin Theories and Tensionless Strings
Publications for 2013
Publications for 2012
Publications for 2011
Publications for 2010
Publications for 2009
Publications for 2008
Publications for 2007
Publications for 2006
Publications for 2005

Cosmological measurements have become increasingly accurate in recent
years and provide stringent constraints on theories of cosmological
evolution. The focus is on the construction of such theories that are
valid below the Planck scale, are minimal in the sense of the dynamical
degrees of freedom needed to achieve realistic evolution, and are
free of fine tunings.
With this in mind, a systematic analysis of gravitation on the quantum infrared level has been done for inflationary spacetime backgrounds. Topics under current study, within the framework of these theories, are: postinflationary evolution, primordial density perturbations, coupling to matter, etc.
Some relevant articles are:
[1] WMAP Three Year Results: Implications for Cosmology
[2] Lectures on the Theory of Cosmological Perturbations
[3] The Quantum Gravitational BackReaction On Inflation
 String theory has provided several new paradigms for fundamental physics.
Some, like extra dimensions of spacetime and the concept of branes
existed before, but obtained a new impetus and necessity in the context of the theory. Other effects as the
geometrization of the gauge interactions via Dbranes, were novel and led to groundbreaking new concepts.
These include the counting of blackhole microstates
explaining the semiclassical BekensteinHawking entropy, the emerging concept of holography and the
bulkboundary correspondence as exemplified by the AdS/CFT correspondence and its generalizations.
Several of the directions of current research here involve directly or indirectly such concepts,
and they will be detailed further in the appropriate places.
Some simple explanations, textbooks and more advanced material can be found at this address.
 If our universe is localized on a pbrane as might be the case in string theory, cosmology both at early and late times can be
very different from the standard cosmology. There are several frameworks for studying the associated problems. They include branes
in almost flat bulk spacetimes, or in the opposite case in strongly curved bulk spacetimes. A well known example in the
second case is the RandallSundrum context. Branes may backreact on the geometry of the bulk or they may be treated as "light" probes.
Cosmology on the branes is then analyzed with the goal of providing new contexts and mechanisms for important cosmological problems
as the causality and flatness problems, as well as the origin of structure in the universe and the nature of dark matter.
A set of recent reviews are:
[1] Brane cosmology: An Introduction.
[2] Lectures on string/brane cosmology.
[3] Dbranes in standard model building, gravity and cosmology.
[4] Braneworld gravity
[5] String Cosmology: A Review.
COSMOLOGY, IR QUANTUM GRAVITY AND INFLATION 
STRING THEORY 
NEW IDEAS IN EARLY UNIVERSE COSMOLOGY FROM STRINGS/BRANES 
IR MODIFICATIONS OF GRAVITY AND DARK ENERGY 
Another approach involves a modification of gravity at large (cosmological) scales. The simplest such modification is a graviton mass, and more sophisticated modifications have been studied. A class of such modifications use higher dimensions and involve brane induced gravity. It seems that there is a general difficulty with changing gravity in the IR showing up as a nonlinear instability (ghosts), strong couplings problems, and fine tuning. Current research is focusing in finding out if this is an omnipresent feature, or if it can be evaded and at what cost. Some recent reviews include
[1] Dynamics of dark energy.
[2] Dark Energy and Dark Gravity
[3] Infraredmodified gravities and massive gravitons.
STRING THEORY AND ITS IMPLICATIONS FOR BEYOND THE STANDARD MODEL PHYSICS 
Heterotic string theory, was the first to be analyzed in the detail, searching for a SM vacuum, due to its promising gauge group in ten dimensions and the fact that it was a theory of closed oriented strings, something that made its consistency conditions simpler to implement. Several vacua were found that were reasonable close in structure to the SM (gauge group, low energy interactions and a reasonable structure of mass spectra). The typical problem with heterotic vacua is that they would need a strong string coupling to accommodate observables like gauge coupling unification or supersymmetry breaking.
In the mid '90s, evidence surfaced that differentlooking string theories are probably related by nonperturbative dualities. This motivated the analysis of open string theories, and their nonperturbative incarnations as heterotic Mtheory and Ftheory. Orientifold vacua and open strings have the advantage that a bottomup construction of the SM seems more suited, giving the hope that the SM search might be simpler than in the heterotic case.
Although the problem has not been solved yet, a large a effort is in place in order to study various aspects of the task. These include:
1. The construction of distinct classes of orientifold vacua.
2. The algorithmization of such constructions in order to perform large scale computer searches.
3. The study of supersymmetry breaking and moduli stabilization with a combination of fluxes and nonperturbative effects.
4. The study of Dinstanton effects and their contributions to the respective low energy effective actions.
5. The study of the geometry of compactification manifolds and their bundles as well as the
stability conditions for Dbranes, populating the associated vacua.
6. The study of the space of vacua of the theory that seems enormous, termed "the landscape", and its implications for physics.
7. The study of generic signatures at LHC of classes of string vacua. The most interesting case seems to be that of anomalous Z' gauge bosons.
The Center is part of an international effort, the "String Vacuum Project" whose goal is to bring together
techniques from physics, mathematics and computer science
in order to tackle the mysteries of the string theory vacua and their relevance for the real world.
Recent reviews on the subjects above are
[0] Dbrane primer.
[1] Lectures on heterotic Mtheory.
[2] Dbranes in standard
model building, gravity and cosmology.
[3] Toward realistic intersecting Dbrane models.
[4]
Orientifolds, hypercharge embeddings and the Standard Model.
[5]
Fourdimensional String Compactifications with DBranes, Orientifolds and Fluxes
[6] Physics of String Flux Compactifications
[7] Overlooking the String Theory Landscape.
[8] Dbrane Instantons in Type II String Theory.
AdSCFT CORRESPONDENCE AND APPLICATIONS TO THE PHYSICS OF QCD 
At its simplest and best understood, the AdS/CFT correspondence asserts the equivalence of 4d N=4 supersymmetric Yang Mills theory on one hand and 10d IIB string theory living on AdS5xS5. At strong 't Hooft coupling the gauge theory description is intractable, while the string theory description can be approximated by twoderivative effective supergravity. This has lead to new insights into the physics of strongly coupled gauge theories. The correspondence was generalized in many directions and its is now called the bulkboundary correspondence, or the holographic correspondence. Nonconformal theories can be involved as well as theories in other dimensions.
An important effort was channeled towards finding the string theory dual of real world QCD. Phenomena that are common in QCD like confinement, a discrete spectrum of glueballs and a mass gap could be described in several string theories that are dual to gauge theories that are confining in the IR. Similarly chiral symmetry breaking and low energy meson dynamics could also be described in related gauge theory duals. However, real world QCD has been so far a challenge, due to the fact that the coupling becomes strong in the UV, and their the geometry becomes stringy. And stringy geometries with RR backgrounds we still have trouble controlling.
Around the same time, experimental efforts at the RHIC Collider have put forward the first convincing evidence that the (thermalized) deconfinement phase of QCD was observed. Together came the realization that this state of matter near the phase transition is strongly coupled, and perturbative approaches cannot describe well its properties. Nonperturbative lattice calculations, although well suited for static properties, are not very useful to calculate dynamical properties including transport coefficients like viscosity.
The viscosity "measured" at RHIC is very close to a conjectured lower bound, found in AdS duals, a fact that sparked interest in AdS/CFT type techniques.
The experimental effort is ongoing and will be continued in LHC, primarily with the ALICE experiment but also the others. Using holographic techniques to calculate in QCD both at zero and finite temperature is still un open problem.
Recent related reviews on the subjects above are
[1] Large N field theories, string theory and gravity.
[2] Microscopic formulation of black holes in string theory.
[4] The NonAdS / nonCFT correspondence, or three different paths to QCD.
[5] Semiclassical strings and AdS/CFT.
[6]
Formation of dense partonic matter in relativistic nucleusnucleus collisions at RHIC
[7] String theory and quarkgluon plasma.
[8] Viscosity, Black Holes, and Quantum Field Theory.
[9] Mesons in Gauge/Gravity Duals  A Review.
[10] Introduction to AdSCFT.
[11] Physics of Strongly coupled QuarkGluon Plasma.
[12]
From gaugestring duality to strong interactions: a Pedestrian's Guide.
AdSCFT CORRESPONDENCE AND APPLICATIONS TO CONDENSED MATTER PROBLEMS 
The particular case of three dimensions (dual to AdS4 vacua) seems well suited to describe quantum systems with essentially twodimensional physics or three dimensional statistical systems. The fact that such theories are at strong coupling explains why the thermodynamics obtained is not always similar to other critical theories. Moreover, in three dimensions there are essentially two alternatives when it comes to scaleinvariant theories.
This is the reason why AdS systems have been used to model condensed matter systems of various sorts, ranging from systems with HighTc superconductivity behavior to strongly interacting cold fermion gases, to systems with strong disorder (spin glasses).
There are no reviews on this subject as it is very young, but some representative papers are given below.
[1] Toward an AdS/cold atoms correspondence: A Geometric realization of the Schrodinger symmetry.
[2] Gravity duals for nonrelativistic CFTs.
[3] Disordered Systems and the Replica Method in AdS/CFT.
[4] Gravity Duals of Lifshitzlike Fixed Points.
Local research efforts focused in the recent past on finding the general cubic coupling of any three HS gauge fields in flat and AdS spaces. In [2] a systematic method based on the triplet construction was presented. In [3] the method above was applied to the simplest case; the interaction between one HS triplet and two massive free scalars. Despite its apparent simplicity this is still a highly nontrivial case since it requires the construction of an infinite number of conserved currents, made out of scalars, that couple properly to HS gauge fields. This is also an important case since it elucidates the emergence of HS gauge fields via the gauging of higher derivative symmetries of free matter Lagrangians.
Current research focuses on the holographic consequences of HS interactions via the AdS/CFT correspondence.
[1] M. A. Vasiliev, Fortsch. Phys. 52, 702 (2004) [arXiv:hepth/0401177].
X. Bekaert, S. Cnockaert, C. Iazeolla and M. A. Vasiliev, [arXiv:hepth/0503128].
D. Sorokin, AIP Conf. Proc. 767, 172 (2005) [arXiv:hepth/0405069].
N. Bouatta, G. Compere and A. Sagnotti, [arXiv:hepth/0409068].
[2] I. L. Buchbinder, A. Fotopoulos, A. C. Petkou and M. Tsulaia, Phys. Rev. D 74 (2006) 105018 [arXiv:hepth/0609082].
[3] A. Fotopoulos, N. Irges, A. C. Petkou and M. Tsulaia, HigherSpin Gauge Fields Interacting with Scalars:
The Lagrangian Cubic Vertex, JHEP 0710 (2007) 021 [arXiv:0708.1399 [hepth]].