I will derive exact analytical expressions for the one-loop partition functions of two nontrivial string configurations in AdS5xS5: a folded, spinning string and a string with world-surface ending on two anti-parallel lines. This way, and via AdS/CFT, one can obtain interesting information on the strong coupling structure of anomalous dimensions for the gauge operators dual to the spinning string, as well as compute the first strong coupling correction to the quark-antiquark potential as defined in N =4 SYM.

According to the AdS/CFT duality a remarkable correspondence exists between strings in AdS and operators in N=4 SYM. A particularly important case is that of folded strings and the so called twist-operators in gauge theory. This is a remarkable tool for uncovering and checking the detailed structure of the AdS/CFT correspondence and its integrability. In this talk I will show how to match the expression of the anomalous dimension of twist operators (cusp anomaly) as computed in string theory with the result obtained from the Bethe ansatz of SYM. This agreement resolves a long-standing disagreement between gauge and string sides of the AdS/CFT duality and provides a highly nontrivial strong coupling test of SYM integrability. I will also comment on the computation of finite size corrections to the cusp anomaly.

This talk will cover two different applications in the study of Hilbert Series. One is in the text book problem of the massive spectrum of the perturbative string in 10 dimensions. We will write the well known partition function in a new form which is covariant under the little group for massive representations. A second application is in the study of flavor invariants in the standard model. We will compute and count all possible invariants which can be constructed from various mass matrices. These two applications are examples of a larger program in which one can use Hilbert series for a collection of problems in physics. .. (Room EB1 is on the lower ground floor of the Queens' building, which is just in front of the Physics building. It's signed as number 16 on the map http://www.qmul.ac.uk/docs/about/26065.pdf The most convenient entrance is on the east side (again just in front of the Physics building): you go down the stairs to the LG floor and then the room is on your right.)

I will review a recent progress in computing scattering amplitudes in N=4 SYM theory and explain the recently found duality between MHV gluon scattering amplitudes and correlation functions of half-BPS protected operators in the limit where the positions of the adjacent operators become light-like separated.

Mumford and Thurston observed that the theory of Jenkins-Strebel differentials can be used to triangulate a compactification of the moduli space of n-pointed Riemann surfaces of given genus. This was later exploited by Kontsevich to prove the Witten conjecture. We review this construction, make a comparison with the Deligne-Mumford compacfication and discuss some of the conjectures in algebraic geometry it led to.

String theory phenomenology generically suffers from either too much flexibility (and lack of predictability) or from the a high specialization to case by case studies. I will discuss how F-theory GUT model building manages to get around these pitfall, in particular, I will explain, how to systematically include global string consistency conditions, which are independent of the specific compactification, and which come with the benefit of highly constraining the class of GUT models that can arise from F-theory.

The partition function of a family of four dimensional N=2 gauge theories has been related by Alday, Gaiotto and Tachikawa (AGT) to correlation functions of two dimensional conformal Toda field theories. For SU(2) gauge theories, the associated two dimensional theory is A1 conformal Toda field theory, i.e. Liouville theory. In this seminar I will discuss how the AGT proposal is modified when the gauge theories include non-local operators. I will focus in particular on Wilson loop operators and a certain type of surface operators in SU(N) N=2 gauge theories. For the case of the surface operator, I will show that the relevant two dimensional field theory is a conformal theory with SL(N) affine algebra. This result generalizes the recent result by Alday and Tachikawa that relates SU(2) gauge theories with surface operators to SL(2) affine algebras.

I will show how to construct gauge-invariant and U-duality covariant expressions for Wess-Zumino terms corresponding to general Dp-branes in arbitrary D less than 10 dimensions. A distinguishing feature of these Wess-Zumino terms is that they contain twice as many scalars as the 10-D compactified dimensions, in line with doubled geometry. It turns out that For D less than 10 the charges of the higher-dimensional branes can all be expressed as products of the 0-brane charges, which include the D0-brane and the NS-NS 0-brane charges. I will show how the general expressions for these charges determine the non-trivial conjugacy class to which some of the higher-dimensional D-branes belong. Some implications and extensions of our work will be discussed.

Particle group seminar. See more information here: http://pprc.qmul.ac.uk/seminars/seminars.html (No seminar in Queen Mary on Thursday.)

Many systems in nature are chaotic, i.e., their classical time evolution depends sensitively on the initial conditions. This has important consequences for their quantum behaviour. In particular the energy levels of chaotic systems display universal statistical properties, and have a tendency to repel each other. I will give an introduction into recent research to explain this universal behaviour. A crucial ingredient is the discovery of correlations between classical periodic orbits. For example if a periodic orbit contains crosses itself with a small angle there is also a partner orbit narrowly avoiding that crossing. In a semiclassical approach one sees that contributions of such correlated orbits can interfere constructively. I will show how this gives rise to universal spectral statistics. I will also discuss connections to random matrix theory (which gives predictions for spectral statistics) as well as the combinatorics of permutations.

AdS_2/CFT_1 correspondence leads to a prescription for computing the degeneracy of black hole states in terms of path integral over string fields living on the near horizon geometry of the black hole. In this talk, I will discuss about how to make use of the enhanced supersymmetries of the near horizon geometry and localization techniques to argue that the path integral receives contribution only from a special class of string field configurations which are invariant under a subgroup of the supersymmetry transformations. I will identify saddle points which are invariant under this subgroup. I will also use this analysis to show that the integration over infinite number of zero modes generated by the asymptotic symmetries of AdS_2 generate a finite contribution to the path integral.

Recent theoretical advances in string theory relate in an unexpected way the physics of gravity in certain D dimensional space-times with the dynamics of quantum field theories living on the associated (D-1) dimensional space-time boundary. This unsuspected relationship offers a remarkable new tool for dealing with some outstanding problems in condensed matter physics. In the first part of the talk I aim to explain both the intuitive and technical underpinnings of these new developments. In the second half of the talk I will present some recent results on aging in systems far from equilibrium and also some new avenues for research in condensed matter physics which involve the interplay of gauge fields, membranes and many-body systems . In particular this last work opens up an exciting possibility for fundamentally new states of condensed matter.

Brane Tilings give a large class of SCFT's in 3+1 and 2+1 dimensions. In this talk I will discuss several attempts to classify all such models. Special attention will be devoted to the class of Abelian orbifolds of C3 and of C4. Statistical properties of these models can be derived using some techniques in crystallography and in number theory.

Non-Gaussianity, which denotes the non-Gaussian feature of the CMB temperature fluctuation, is potentially the most promising probe of inflation. In this talk, we discuss some recent research topics in this field, namely non-Gaussianity for DBI inflation, quasi-single field inflation and multi-stream inflation. Special attention is paid on the relation between non-Gaussianity and string theory.

We will discuss a special class of higher derivative gravity theories called Lovelock gravities, in the context of holography. For a generic Lovelock gravity in arbitrary dimensions, we will formulate the existence condition for asymptotically AdS black holes. Then, causality of the dual finite temperature CFT will be shown to impose constraints on the Lovelock parameters. Calculation of the holographic Weyl anomaly in 6+1 dimensions reveals that these constraints are completely equivalent to the ones determined by requiring positivity of the energy flux. Implications of these results on the viscosity to entropy bound will also be discussed. This talk is based on hep-th/0910.5347, 0912.1877, 0912.4244.

We will show that a large class of N=2 SUSY field theories do not have SUSY breaking vacua.

In this talk I will discuss the apparent integrability of large N ABJM models and the possible integrability of its ABJ extension. I will also discuss recent work to compute a coupling dependent function that explicitly appears in the magnon dispersion relations and Bethe equations for these models.

I will discuss the first construction of coherent states (and other massive states with arbitrarily exited harmonics) in the covariant formalism for both open and closed strings with applications to cosmic strings in mind. Furthermore, I provide an explicit map that relates three different descriptions of cosmic strings: classical strings, lightcone gauge quantum states and covariant vertex operators, highlighting the virtues and shortcomings of each. I will then go on to discuss applications and future directions: string amplitude computations with such vertices and in particular decays of (the phenomenologically promising) cosmic strings with non-degenerate cusps in a framework that naturally incorporates the effects of gravitational backreaction.