Conference

Dark matter models with an annihilation cross section enhanced by a Sommerfeld mechanism have been proposed in the past years to explain a number of observed anomalies, such as the excess of high energy positrons in cosmic rays reported by PAMELA. However, this enhancement can not be arbitrarily large without violating a number of astrophysical measurements. In this talk, I will discuss the degree to which these measurements can constrain Sommerfeld-enhanced models. In particular, I will talk about constraints coming from the observed abundance of dark matter and the extragalactic background light measured at multiple wavelengths.

No known astrophysical mechanisms are expected to generate a significant high-energy flux of cosmic-ray electrons and positrons (CREs) from the Sun. However, some recently considered classes of dark matter models predict such a signal. We analyzed the CRE events collected by the Fermi-LAT during its first year of operation to search for a flux excess correlated with the Sun's direction, and found no evidence of a significant signal. I will discuss the constraints these results place on secluded dark matter models and inelastic dark matter models.

One of the most exciting, albeit slightly speculative, components of the Fermi mission is to search for evidence of energetic events related to dark matter decay or annihilation. The best targets for this search a regions where we suspect there is dark matter, but see few conventional gamma-ray sources such as molecular clouds, cosmic ray sources, or compact objects. Much emphasis has been placed on local dwarf satellites in particular, since many of these systems show evidence for relatively deep potential wells, but have few stars and no recent star formation. In this talk I will propose another possible target for indirect dark matter searches, among our nearby galactic neighbours.

The existence of dark matter is hardly in doubt, yet astrophysicists continue to search in vain for any non-gravitational signals of it. In the case of weakly interacting massive particle (WIMP) models, ongoing annihilation or decay of WIMPs to Standard Model particles could provide observable signals, e.g. as excess gamma rays in the center of the Milky Way or as excess ionization at high redshift. I will present our latest results on the most rigorous constraint from astrophysics: the effect of WIMP annihilation on the ionization history of the Universe, as recorded in the CMB.

A wide range of results have led to a confusing situation in the area of direct WIMP detection. I'll review the status of these results. The features of the results imply that almost any explanation will require a departure from standard assumptions (Maxwellian halo, elastic WIMP scattering or otherwise) so I'll review the techniques to compare experiments without appealing to these assumptions. In particular, I'll comment on the status of light WIMPs and the iodine interpretations of DAMA (such as inelastic dark matter) in light of the most recent results.

We study the dimensions of non-chiral operators in the Veneziano limit of N=1 supersymmetric QCD in the conformal window. We show that when acting on gauge-invariant operators built out of scalars, the 1-loop dilatation operator is equivalent to the spin chain Hamiltonian of the 1D Ising model in a transverse magnetic field, which is a nontrivial integrable system that is exactly solvable at finite length. Solutions with periodic boundary conditions give the anomalous dimensions of flavor-singlet operators and solutions with fixed boundary conditions give the anomalous dimensions of operators whose ends contain open flavor indices.

The motion of superstrings on symmetric space target spaces is classically equivalent, via the Pohlmeyer reduction, to a family of 2-d relativistic integrable field theories known as semisymmetric space sine-Gordon (SSSSG) theories. In this talk I will review recent progress in constructing the relativistic S-matrix corresponding to the quantum solution of the AdS5 x S5 SSSSG theory.

I will present a first-principles derivation of the AdS5/CFT4 T-system up to first non-trivial order in the large 't Hooft coupling expansion. The proof relies on the computation of quantum effects in the fusion of some special line operators, namely the transfer matrices. This computation is done in the pure spinor formalism for the superstring in AdS5xS5. I will also discuss the generalization of this computation to other integrable 2D CFTs that define string theory in AdS backgrounds.

I will show how to solve the AdS/CFT Y-system in terms of a finite set of nonlinear integral equations (FiNLIE). To uniquely define the solution we impose the set of constraints on the Y- and T-functions which can be summarized as: symmetry (PSU(2,2|4) + Z_4) + analyticity + large volume asymptotics. Some of these constraints describe previously unknown properties of the Y-system. As an important check of our approach, we showed that the proposed constraints can be also used to derive the infinite set of the TBA equations. We also successfully checked FiNLIE numerically for the case of Konishi operator.

The TBA approach to the AdS/CFT spectral problem is used to compute scaling dimensions of several operators dual to two-particle states of the l.c. AdS5 x S5 string theory. The implementation of the psu(2,2|4) symmetry in the TBA framework is discussed.