# Cosmological Frontiers in Fundamental Physics 2010

Conference Date:
Tuesday, June 15, 2010 (All day) to Friday, June 18, 2010 (All day)
Scientific Areas:
Cosmology
Particle Physics
Quantum Fields and Strings
Quantum Gravity

The purpose of this informal workshop is to discuss and exchange ideas on recent developments at the interface of modern cosmology and fundamental physics.

This workshop is the fourth in a series organized jointly by the International Solvay Institutes, APC (Université Paris VII, Paris) and the Perimeter Insitute (Waterloo, Canada).

Invited Speakers:

• Dick Bond, CITA, University of Toronto
• Curt Cutler, California Institute of Technology
• Ruth Durrer, Université de Genève
• Ben Freivogel, University of California, Berkeley
• Steven Giddings, University of California, Santa Barbara
• Jonathan Heckman, Institute for Advanced Study
• Thomas Hertog, APC Paris/Solvay Institute
• Richard Holman, Carnegie Mellon University
• Gary Horowitz, University of California, Santa Barbara
• Alex Maloney, McGill University
• Jim Peebles, Princeton University
• Ue-Li Pen, CITA, University of Toronto
• Maxim Pospelov, Perimeter Institute/University of Victoria
• Leonardo Senatore, Institute for Advanced Study
• Eva Silverstein, KITP, University of California, Santa Barbara
• Kostas Skenderis, Universiteit van Amsterdam
• Lenny Susskind, Stanford University
• Neil Turok, Perimeter Institute
• Licia Verde, Institute of Cosmos Sciences, University of Barcelona
• Neal Weiner, CCPP, New York University
• Alexander Westphal, Stanford University
• Matias Zaldarriaga, Institute for Advanced Study

Curt Cutler, California Institute of Technology

Cosmology with 300,000 Standard Sirens

I will describe recent work by Cutler&Holz and Hirata, Holz, & Cutler showing that a highly sensitive, deci-Hz gravitational-wave mission like BBO or Decigo could measure cosmological parameters, such as the Hubble constant H_0 and the dark energy parameters w_0 and w_a, far more accurately than other proposed dark-energy missions.   The basic point is that BBO’s angular resolution is so good that it will provide us with hundreds of thousands of “standard sirens.”  These standard sirens are inspiraling neutron star and black hole binaries, with gravitationally-determined distances and optically determinable redshifts.  I explain why a BBO-like mission would also be a powerful weak lensing mission, and I briefly describe some further astrophysics that would flow from such a mission.

Ruth Durrer, Université de Genève

The generation of primordial magnetic fields

Magnetic fields are ubiquitous in our Universe. The are observed in galaxies and clusters in our vicinity and at high redshifts.

In my talk I outline the possibilities to generate magnetic fields in the early Universe during inflation or during a first order phase transition. I explain the form of the magnetic field spectrum obtained in the different cases. I also discuss the subsequent evolution of helical and non-helical magnetic fields in the cosmological plasma and argue that fields generated at the electroweak phase transition do not have enough large scale power to represent the magnetic fields observed in galaxies and clusters, even if they are maximally helical.

Ben Freivogel, University of California, Berkeley

Regulating Eternal Inflation with the UV/IR connection

I will discuss a recent proposal to regulate the infinities of eternal inflation by relating a late-time cutoff in the bulk to a short-distance cutoff on the conformal boundary of the spacetime.

Steve Giddings, University of California, Santa Barbara

IR effects, semiclassical relations, and perturbative limitations in inflationary spacetimes

TBA

Thomas Hertog, APC Paris & Solvay Institute

Eternal Inflation without Metaphysics

TBA

Richard Holman, Carnegie Mellon University

Infrared Issues in de Sitter Space: Secular Growth of Fluctuations and the Breakdown of the Semiclassical Approximation.

I'll discuss some work done in collaboration with Cliff Burgess, Louis Leblond and Sarah Shandera on the significance of the IR divergences in de Sitter space. First, I'll talk about how large fluctuations at long distances can induce the failure of the loop expansion for interacting field theories with massless degrees of freedom in de Sitter space, much in the same manner as happens in thermal field theories. Then I'll shift gears slightly and describe work involving the use of the dynamical renormalization group in resumming the secularly growing perturbative corrections to correlation functions for massless, minimally coupled scalar fields in de Sitter.

Gary Horowitz, University of California, Santa Barbara

Update on a Holographic Description of Singularities

TBA

Alex Maloney, McGill University

On the Microscopic Description of the Kerr Black Hole

We describe recent progress on the quantum description of the Kerr black hole.  Previous descriptions of black hole microstates have relied on the existence of near-horizon regions with conformal symmetry, and hence have only worked for extremal or supersymmetric black holes.  We argue that the states of non-extremal black holes can also be understood in terms of a conformal symmetry, the difference being that this symmetry is not geometrically realized.  Thus a Kerr black hole is an excited state of a conformal field theory.  By making certain (natural) assumptions about the nature of this dual CFT we can compute its density of states.  This gives a microscopic computation of the Bekenstein-Hawking entropy of a Kerr black hole with arbitrary mass and angular momentum.

Jim Peebles, Princeton University

Hints from galaxies to a still better cosmology

The network of tests shows the LCDM cosmology is a good approximation to what actually happened, but that need not mean it has all the physics relevant to cosmology back to light element formation. I will review properties of galaxies that seem to be particularly difficult to understand within LCDM and might be pointing to still better physics.

Eva Silverstein, KITP, University of California, Santa Barbara

Micromanaging de Sitter holography

TBA

Kostas Skenderis, Universiteit van Amsterdam

Holographic Non-Gaussianity

We discuss holographic models for the inflationary epoch. We show how cosmological observables such as the primordial spectrum and non-Gaussianities can be computed via computations of correlation functions of a dual three dimensional QFT (without gravity!) We present a general class of models that have the following universal features: (i) they have a nearly scale invariant spectrum of small amplitude primordial fluctuations, (ii) the scalar spectral index runs as alpha_s = - (n_s-1), (iii) the three point function of density perturbations is exactly equal to the sum of the local and equilateral form with f_{NL}^{local} = 6 f_{NL}^{equil} = 20/3.

Neil Turok, Perimeter Institute

Holographic Singularity Resolution

TBA

Licia Verde, Institute of Cosmos Sciences, University of Barcelona

Constraining primordial non-Gaussianity with large-scale structure

Constraining primordial non-Gaussianity can offer a window into the early universe, and into testing the inflationary paradigm, which is fully complementary to  the approach offered by Cosmic Microwave Background polarization. Large-scale structure and galaxy surveys have recently received renewed attention as a way to constrain primordial non-Gaussianity. I will review the potential and the limitations of this approach and highlight its complementarity to  Cosmic Microwave Background observations.

Alexander Westphal, Stanford University

A comment on gravitational waves and the scale of supersymmetry breaking

It has been suggested, by Kallosh and Linde, that a generic bound on inflation in string theory keeps the

Hubble scale of inflation $H$ smaller than the gravitino mass, $m_{3/2}$. Given that models with low-energy supersymmetry have $m_{3/2}$ smaller than a TeV, this is a severe constraint, and would suggest that one is forced to choose between high-scale inflation and low-scale supersymmetry.   The bound arises by considering possible decompactification instabilities of the extra (compactified) dimensions of string theory, during the inflationary epoch.  I explain the arguments that give rise to such a bound, and describe recent work with T. He and A. Westphal exhibiting large-field chaotic inflation models in string-inspired supergravities that have $H >> m_{3/2}$ but avoid decompactification. I conclude that even within the framework of string theory, high-scale inflation and low-energy supersymmetry may well be compatible.

Pierre Binetruy, APC/Universit Paris VII

Marc Henneaux, ULB/Solvay

Gary Horowitz, UCSB

Juan Maldacena. IAS

Valery Rubakov, RAS

Organizing Committee:

Andrew Tolley, Perimeter Institute

Niayesh Afshordi, Perimeter Institute/University of Waterloo

Latham Boyle, Perimeter Institute/CITA

Ben Craps, Solvay/Vrije Universiteit Brussel