The Cosmological Slingshot Scenario: a Stringy Proposal for the Early Time Cosmology

In the Cosmological Slingshot Scenario, our Universe is a D3-brane that extends in the 4d noncompact directions of a warped Calabi-Yau compactification of IIB Supergravity. Early time cosmology corresponds to a period in which the brane moves inside a warped throat where a non-vanishing angular momentum ensures that the trajectory of the brane has a turning point. The corresponding induced metric on the D3-brane experiences a cosmological evolution with a bounce. In this framework, the homogeneity, flatness, and isotropy problems of standard cosmology might be avoided. The power spectrum of primordial perturbations of the brane embedding can be found and it is shown to be in agreement to WMAP data.Comment: Presented at "Ten Years of AdS/CFT: A Workshop Celebrating the Tenth Anniversary of the Maldacena Conjecture", Buenos Aires, Argentina, 19-21 Dec 200

Uses of Chern-Simons actions

The role of Chern-Simons (CS) actions is reviewed, starting from the observation that all classical actions in Hamiltonian form can be viewed as 0+1 CS systems, in the same class with the coupling between the electromagnetic field and a point charge. Some suggestions are derived that could shed some light on the quantization problem in D=2n-1>3 dimensions.Comment: 17 pages, no figures. Ten Years of AdS/CFT conference, a workshop to celebrate the tenth anniversary of the Maldacena Conjecture. Buenos Aires, December 2007. Added references, corrected typo

On SUGRA description of boost-invariant conformal plasma at strong coupling

We study string theory duals of the expanding boost invariant conformal gauge theory plasmas at strong coupling. The dual supergravity background is constructed as an asymptotic late-time expansion, corresponding to equilibration of the gauge theory plasma. The absence of curvature singularities in the first few orders of the late-time expansion of the dual gravitational background unambiguously determines the equilibrium equation of the state, and the shear viscosity of the gauge theory plasma. While the absence of the leading pole singularities in the gravitational curvature invariants at the third order in late-time expansion determines the relaxation time of the plasma, the subleading logarithmic singularity can not be canceled within a supergravity approximation. We comment on the possible interpretations of this singularity.Comment: 10 pages, presented at "Ten Years of AdS/CFT", December 19-21, 200

Particle phenomenology and Maldacena

A brief review is offered of employing Maldacena's AdS/CFT correspondence in attempting to identify a model which extends to higher energy the standard model of particle phenomenology.Comment: Talk at "Ten Years of AdS/CFT", Buenos Aires,December 19-21,2007. 11 pages late

On the S-Matrix of the Faddeev-Reshetikhin Model

The Faddeev-Reshetikhin model arises as a truncation of strings in AdS_5XS^5. Its two particle S-matrix should be obtained by diagonalizing its Hamiltonian. However this does not happen in a straightforward way. There is a Lorentz violating term in the Hamiltonian which prevents its plain diagonalization. We then find out the most general quartic Hamiltonian that can be diagonalized. It includes the bosonic Thirring model as well as another model which shares the same two particle S-matrix as the Faddeev-Reshetikhin model. We also find a one parameter family of interactions which lead to non-Hermitian Hamiltonians which have unitary S-matrices and are PT symmetric.Comment: 7 pages, aipproc macros required; talk given at "Ten Years of AdS/CFT", Buenos Aires, December 19-21, 200

Jet Quenching in Heavy Ion Collisions from AdS/CFT

The phenomenon of jet supression observed in highly energetic heavy ion collisions is discussed. The focus is devoted to the stunning applications of the AdS/CFT correspondence to describe these real time processes, hard to be illuminated by other means. In particular, the introduction of as many flavors as colors into the quark-gluon plasma is scrutinized.Comment: 14 pages; talk given at "Ten Years of AdS/CFT: A Workshop Celebrating the Tenth Anniversary of the Maldacena Conjecture", Buenos Aires, December 200

The status of the KSS bound and its possible violations (How perfect can a fluid be?)

In this work we briefly review the Kovtun-Son-Starinet (KSS) computation of the ratio eta/s for quantum field theories with gravitational dual and the related conjecture that it is bound from below by 1/(4 pi). We discuss the validity of the bound and the nature of its possible violations, its relevance for RHIC, its connection with phase transitions and other related issues.Comment: 10 pages, 5figs, Invited talk at "10 years of AdS/CFT Correspondence", Buenos Aires, Dec. 2007, honoring Juan Maldacen