Conference

Displaying 2869 - 2880 of 4881

Black hole evaporation and unitarity: a semi-classical resolution?

James Bardeen

July 10, 2013

PIRSA:13070011
Testing inflation with combined power- and bispectrum

July 10, 2013

PIRSA:13070012
Planck and beyond

Martin Bucher French National Centre for Scientific Research (CNRS)

July 10, 2013

PIRSA:13070014
21cm cosmology

Ue-Li Pen Canadian Institute for Theoretical Astrophysics (CITA)

July 10, 2013

PIRSA:13070010
A unifying approach to dark energy models

David Langlois Université Paris Cité

July 09, 2013

PIRSA:13070023
Resolution of Cosmic Singularities and Bounces

Neil Turok University of Edinburgh

July 09, 2013

PIRSA:13070008
Cosmological Magnetic Fields

Tanmay Vachaspati University of Arizona

July 09, 2013

PIRSA:13070007
Remarks on Gravitational Duality

Marc Henneaux International Solvay Institutes

July 09, 2013

PIRSA:13070020
Bimetric theory, Conformal Gravity and Partial Masslessness

Fawad Hassan Stockholm University

July 09, 2013

PIRSA:13070021
Solid Inflation

Alberto Nicolis Columbia University

July 09, 2013

PIRSA:13070005
Cosmological Limits on Neutrino-Neutrino Scattering and Particle Physics in the Early Universe

Kris Sigurdson University of British Columbia

July 09, 2013

PIRSA:13070025
Primordial non-Gaussianity in the CMB and large-scale structure

Kendrick Smith Perimeter Institute for Theoretical Physics

July 08, 2013

PIRSA:13070001

Black hole evaporation and unitarity: a semi-classical resolution?

James Bardeen

July 10, 2013

PIRSA:13070011

I explore the possibility that semi-classical back-reaction, due to the partners of the Hawking radiation quanta accumulating over the time for the black hole to lose about one half of its mass (the Page time), might cause the trapped surfaces to disappear, permitting unitary evolution without any cloning of quantum information.
Testing inflation with combined power- and bispectrum

July 10, 2013

PIRSA:13070012
Planck and beyond

Martin Bucher French National Centre for Scientific Research (CNRS)

July 10, 2013

PIRSA:13070014

After reviewing some of the highlights of the implications of the Planck results for cosmic inflation (presentation to be coordinated with Hiranya Peiris), I will discuss some recent developments
regarding future searches for B modes and other new science resulting from an ultra-precise
characterization of the microwave and far-infrared sky in polarization. I will outline ideas for
a recently proposed large-class European Space Agency mission called PRISM.
21cm cosmology

Ue-Li Pen Canadian Institute for Theoretical Astrophysics (CITA)

July 10, 2013

PIRSA:13070010

I will overview the progress of 21cm cosmology, with emphasis on intensity mapping. Current and future experiments have the potential for precision measurements of dark energy, neutrino mass, and gravitational waves.
A unifying approach to dark energy models

David Langlois Université Paris Cité

July 09, 2013

PIRSA:13070023

This talk will present an effective description of single field dark energy/modified gravity models, which encompasses most existing proposals. The starting point is a generic Lagrangian expressed in terms of the lapse and of the extrinsic and intrinsic curvature tensors of the uniform scalar field hypersurfaces. By expanding this Lagrangian up to quadratic order, one can describe the homogeneous background and the dynamics of linear perturbations. In particular, one can identify seven Lagrangian operators that lead to equations of motion containing at most second order derivatives, the time-dependent coefficients of three of these operators characterizing the background evolution. I will illustrate this approach with Horndeski's---or generalized Galileon---theories. Finally, I will discuss the link between this effective approach and observations.
Resolution of Cosmic Singularities and Bounces

Neil Turok University of Edinburgh

July 09, 2013

PIRSA:13070008

The AdS/CFT correspondence provides new insights and tools to answer previously inaccessible questions in quantum gravity. Among the most interesting is whether it is possible to describe a cosmological "bounce" in a mathematically complete and consistent way. In the talk, I'll discuss joint work with M. Smolkin, developing the dual description of the simplest possible 4d M-theory cosmology in the stringy regime, employing the full quantum dynamics of its dual CFT. I'll also present evidence that the description extends to the Einstein-gravity regime.
Cosmological Magnetic Fields

Tanmay Vachaspati University of Arizona

July 09, 2013

PIRSA:13070007
Remarks on Gravitational Duality

Marc Henneaux International Solvay Institutes

July 09, 2013

PIRSA:13070020
Bimetric theory, Conformal Gravity and Partial Masslessness

Fawad Hassan Stockholm University

July 09, 2013

PIRSA:13070021

Ghost-free bimetric theories can be used to describe gravitational interactions in the presence of an extra neutral massive
spin-2 field that can modify gravity in non-trivial ways. They also
provide a natural framework for a possible non-linear extension of
partially masslessness known to arise in linear Fierz-Pauli theory.
This talk will describe bimetric theories and a procedure that
identifies a unique bimetric action as a candidate for a nonlinear
partially massless theory. We then show that in the low curvature
limit, the candidate partial massless theory is related to Conformal
Gravity.
Solid Inflation

Alberto Nicolis Columbia University

July 09, 2013

PIRSA:13070005

I will describe a cosmological model where primordial inflation is driven by a 'solid', defined as a system of three derivatively coupled scalar fields obeying certain symmetries and spontaneously breaking a certain subgroup of these. The symmetry breaking pattern differs drastically from that of standard inflationary models: time translations are unbroken. This prevents our model from fitting into the standard effective field theory description of adiabatic perturbations, with crucial consequences for the dynamics of cosmological perturbations. Most notably, non-gaussianities in the curvature perturbations are unusually large, with f_NL ~ 1/(\epsilon.c_s^2), and have a novel shape: peaked in the squeezed limit, with anisotropic dependence on how the limit is approached. Other unusual features include the absence of adiabatic fluctuation modes during inflation---which does not impair their presence and near scale-invariance after inflation---and a slightly blue tilt for the tensor modes.
Cosmological Limits on Neutrino-Neutrino Scattering and Particle Physics in the Early Universe

Kris Sigurdson University of British Columbia

July 09, 2013

PIRSA:13070025

In the standard model neutrinos are assumed to have streamed across the Universe since they last scattered at the weak decoupling epoch when the temperature of the standard-model plasma was ~MeV. The shear stress of free-streaming neutrinos imprints itself gravitationally on the Cosmic Microwave Background (CMB) and makes the CMB a sensitive probe of neutrino scattering. Yet, the presence of nonstandard physics in the neutrino sector may alter this standard chronology and delay neutrino free-streaming until a much later epoch. We will discuss how observations of the CMB can be used to constrain the strength of neutrino self-interactions G_eff and put limits on new physics in the neutrino sector from the early Universe. Key measurements of the CMB at large multipoles made by the Planck satellite and high-l experiments are critical for probing this physics. Within the context of conventional LambdaCDM parameters cosmological data are compatible with G_eff < 1/(56 MeV)^2 and neutrino free-streaming might be delayed until their temperature has cooled to as low as ~25 eV. Intriguingly, we also find an alternative cosmology compatible with cosmological data in which neutrinos scatter off each other until z~10^4 with a preferred interaction strength in a narrow region around G_eff = 1/(10 MeV)^2. This distinct self-interacting neutrino cosmology is characterized by somewhat lower values of both the scalar spectral index and the amplitude of primordial fluctuations. We phrase our discussion in terms of a specific scenario in which a late onset of neutrino free-streaming could occur, but in fact our constraints on the neutrino visibility function are very general.
Primordial non-Gaussianity in the CMB and large-scale structure

Kendrick Smith Perimeter Institute for Theoretical Physics

July 08, 2013

PIRSA:13070001

Title	Speaker(s)	Date	Talk Type	Info link
Black hole evaporation and unitarity: a semi-classical resolution?	James Bardeen	2013-07-10	Conference	View details
Testing inflation with combined power- and bispectrum		2013-07-10	Conference	View details
Planck and beyond	Martin Bucher	2013-07-10	Conference	View details
21cm cosmology	Ue-Li Pen	2013-07-10	Conference	View details
A unifying approach to dark energy models	David Langlois	2013-07-09	Conference	View details
Resolution of Cosmic Singularities and Bounces	Neil Turok	2013-07-09	Conference	View details
Cosmological Magnetic Fields	Tanmay Vachaspati	2013-07-09	Conference	View details
Remarks on Gravitational Duality	Marc Henneaux	2013-07-09	Conference	View details
Bimetric theory, Conformal Gravity and Partial Masslessness	Fawad Hassan	2013-07-09	Conference	View details
Solid Inflation	Alberto Nicolis	2013-07-09	Conference	View details
Cosmological Limits on Neutrino-Neutrino Scattering and Particle Physics in the Early Universe	Kris Sigurdson	2013-07-09	Conference	View details
Primordial non-Gaussianity in the CMB and large-scale structure	Kendrick Smith	2013-07-08	Conference	View details

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Format results

Black hole evaporation and unitarity: a semi-classical resolution?

Testing inflation with combined power- and bispectrum

Planck and beyond

21cm cosmology

A unifying approach to dark energy models

Resolution of Cosmic Singularities and Bounces

Cosmological Magnetic Fields

Remarks on Gravitational Duality

Bimetric theory, Conformal Gravity and Partial Masslessness

Solid Inflation

Cosmological Limits on Neutrino-Neutrino Scattering and Particle Physics in the Early Universe

Primordial non-Gaussianity in the CMB and large-scale structure

Black hole evaporation and unitarity: a semi-classical resolution?

Testing inflation with combined power- and bispectrum

Planck and beyond

21cm cosmology

A unifying approach to dark energy models

Resolution of Cosmic Singularities and Bounces

Cosmological Magnetic Fields

Remarks on Gravitational Duality

Bimetric theory, Conformal Gravity and Partial Masslessness

Solid Inflation

Cosmological Limits on Neutrino-Neutrino Scattering and Particle Physics in the Early Universe

Primordial non-Gaussianity in the CMB and large-scale structure