Scientific Series

This talk will describe the best current understanding of the interior structure of astronomically realistic black holes. A common misconception is that matter falling into a black hole simply falls to a central singularity, and that's that. Reality is much more interesting. Rotating black holes have not only outer horizons, but also inner horizons. Penrose (1968) first pointed out that an infaller falling through the inner horizon would see the outside Universe infinitely blueshifted, and he speculated that this would destabilize the inner horizon. The expectation was supported by linear perturbation theory, but it was not until 1990 that Poisson & Israel were able to clarify the nonlinear evolution of the instability at the inner horizon, which they called mass inflation. Inflation accelerates ingoing (positive energy) and outgoing (negative energy) streams to exponentially huge energies. The black hole thus behaves like a particle accelerator of extraordinary power, accelerating ingoing and outgoing particles to collide with each other at super-Planckian energies. The talk raises the fundamental question: What does Nature do with this remarkable accelerator?

The dynamics of fluids is a long standing challenge that remained as an unsolved problem for centuries. Understanding its main features, chaos and turbulence, is likely to provide an understanding of the principles and non-linear dynamics of a large class of systems far from equilibrium. We consider a conceptually new viewpoint to study these features using black hole dynamics. Since the gravitational field is characterized by a curved geometry, the gravity variables provide a geometrical framework for studying the dynamics of fluids: A geometrization of turbulence. We present new experimental predictions for relativsitic and non-relativistic turbulent flows and for heavy ion collisions.

I will discuss the emergence of large, localized, pseudo-stable configurations (oscillons) from inflaton fragmentation at the end of inflation. Remarkably, the emergent oscillons take up >50 per cent of the energy density of the inflaton. First, I will give an overview of oscillons, provide some analytic solutions and discuss their stability. Then, I will discuss the conditions necessary for their emergence and provide estimates for their cosmological number density. I will show results from detailed 3+1-dimensional numerical simulations and compare them to the analytic estimates. Finally, I discuss possible observational consequences of oscillons in the early universe.

Single-sector supersymmetry breaking models provide a unified explanation of two of the central mysteries of fundamental physics: the Planck/Weak hierarchy and the masses and mixings of the Standard Model particles. In this class of models, the flavor hierarchy is generated by quark and lepton compositeness, with the composites emerging from the same sector that dynamically breaks supersymmetry. In this seminar I will describe the first calculable, via a weakly coupled dual description, realization of this scenario. In the second part, I will explain how String Theory provides, via the gauge/gravity correspondence, another computational tool for handling the kind of strongly coupled gauge theories that arise in this context.

The consequences of the fact that electroweak scale particles are often produced beyond threshold has been appreciated only recently. Decay products of boosted objects tend to be collimated and their final state radiation (FSR) might overlap. It has been shown that it can be advantageous to collect all FSR of a decaying resonance in a so-called 'fat jet' and apply subjet techniques to it to obtain a good mass reconstruction of the resonance and an improved background rejection. In my talk I would like to cover recent developments in this field and discuss applications to Higgs searches and top reconstruction within and beyond the Standard Model.

In the context of loop quantum gravity and spin foam models, the simplicity constraints are essential in that they allow to write general relativity as a constrained topological theory. I will first recall the spin foam quantization procedure and focus more particularly on the step consisting in implementing the simplicity constraints. Then, I will present the U(N) framework initially developed for SU(2) intertwiners. Finally, I will show how we can apply this new framework to impose the simplicity constraints in the context of 4d Euclidean gravity and present new solutions defined in term of U(N) coherent states.

The gravitational observatory LISA will detect radiation from massive black hole sources at cosmological distances, accurately measure their luminosity distance and help identify the electromagnetic counterparts that such sources may generate. I will describe various astrophysical scenarios for the generation of electromagnetic counterparts and discuss observational strategies aimed at identifying them. Successful identifications will enable novel studies of black hole astrophysics and cosmological physics.

Hydrodynamics is the universal theory describing the behavior of fluids when their spacetime variation is on scales longer than any microphysical scale in the fluid. Relativistic hydro has applications in heavy ion collisions and early Universe cosmology, and has seen a surge of interest due to heavy ion experiments and theoretical developments in AdS/CFT. I will explain what second order hydrodynamics is and why it is the minimum theory to study in the relativistic case. Then I discuss some limitations of the theory, including a new bound on how small the viscosity can be and a complication in the rigorous definition of the viscous relaxation time

An ultraviolet complete quantum gravity theory is formulated in which vertex functions in Feynman graphs are entire functions and the propagating graviton is described by a local, causal propagator. A scalar-tensor action describes classical gravity theory. The cosmological constant problem is investigated in the context of the ultraviolet complete quantum gravity. Also investigated are black holes and cosmology.

I will present the latest results from the searches for gravitational waves from the coalescence of binary systems of neutron stars and black holes in LIGO and Virgo data. We present results on data from the Fifth Science Run LIGO run S5 from Nov 2005 to Oct 2007, which was joint with Virgo's first Science Run VSR1 from May to Oct 2007. We also show how these methods are being applied in the current LIGO S6/ Virgo VSR2 data-taking run started in July 2009, and recently ended in October 2010.

In this talk I will describe my recent work on the structure of entanglement in field theory from the point of view of mutual information. I will give some basic scaling intuition for the entanglement entropy and then describe how this intuition is better captured by the mutual information. I will also describe a proposal for twist operators that can be used to calculate the mutual information using the replica method. Finally, I will discuss the relevance of my results for holographic duality and entanglement based simulation methods for many body systems.