Scientific Series

Displaying 3457 - 3468 of 4903

Voids in the SDSS: from demography to cosmology

Paul Sutter Institut d'Astrophysique de Paris
October 09, 2012

PIRSA:12100041
Astrophysics
Scalars with Higher Derivatives in Supergravity and Cosmology

Jean-Luc Lehners Koehn AI
October 09, 2012

PIRSA:12100042
Astrophysics
Testing Strong-Field General Relativity with Black Holes

Tim Johannsen

October 04, 2012

PIRSA:12100049
A Higgs but no sparticles yet: what it means for the (p)MSSM

Ahmed Ismail University of Pittsburgh
October 02, 2012

PIRSA:12100052
High Energy Physics
Homogeneous and Isotropic Universe from Nonlinear Massive Gravity

A. Emir Gumrukcuoglu
October 02, 2012

PIRSA:12100002
Astrophysics
New Observations about the Renormalization Group Flow

Zohar Komargodski Stony Brook University
September 26, 2012

PIRSA:12090058
High Energy Physics
Large-N Collective Fields and de Sitter / CFT correspondence

Sumit Das University of Kentucky
September 25, 2012

PIRSA:12090045
General Relativity & Quantum Cosmology

High Energy Physics
Supermassive black holes in non-spherical galactic nuclei and enhanced rates of star capture events

Eugene Vasiliev Rochester Institute of Technology
September 25, 2012

PIRSA:12090064
Astrophysics
A generalization of Kochen-Specker sets

Laura Mancinska Institute for Quantum Computing (IQC)

September 24, 2012

PIRSA:12090073
Effect of thermal fluctuations in topological p-wave superconductors

Bela Bauer Microsoft Corporation
September 21, 2012

PIRSA:12090039
Condensed Matter
The Higgs Boson and speculative particle physics

Mark Wise California Institute of Technology (Caltech)

September 19, 2012

PIRSA:12090065
Jet Substructure, by Accident

Eder Izaguirre LinkedIn (United States)
September 18, 2012

PIRSA:12090063
High Energy Physics

Voids in the SDSS: from demography to cosmology

Paul Sutter Institut d'Astrophysique de Paris
October 09, 2012

PIRSA:12100041
Astrophysics
Cosmic voids are potentially a rich source of information for both astrophysics and cosmology. To enable such science, we produce the most comprehensive void catalog to date using the Sloan Digital Sky Survey Data Release 7 main sample out to redshift z = 0.2 and the Luminous Red Galaxy sample out to z = 0.44. Using a modified version of the parameter-free void finder ZOBOV, we fully take into account the presence of survey boundary and masks. We discuss basic catalog statistics such as number counts and redshift distributions, as well as describe some example data products derived from our catalog, such as radial density profiles and projected density maps. Using this catalog, we report on the first application of the Alcock-Paczynski test to stacked voids in spectroscopic redshift surveys by applying the shape-fitting procedure presented in Lavaux & Wandelt (2011) to ten void stacks out to redshift z = 0.36. Our results are consistent with WMAP 7-year cosmological constraints. We compare our results to alternate methods of constructing void stacks and comment on future observational prospects.
Scalars with Higher Derivatives in Supergravity and Cosmology

Jean-Luc Lehners Koehn AI
October 09, 2012

PIRSA:12100042
Astrophysics
There are many situations in cosmology that motivate the study of scalar fields with higher-derivative actions. The best-known such situations are probably k-inflation (with DBI-inflation being a special case) and models based on galileon theories, but even eternal inflation and cyclic universes provide good reasons to study such theories. After an extended discussion of the motivations, I will show how scalar field theories with higher derivatives can be constructed in (minimal, 4-dimensional) supergravity, and will discuss their properties, especially in regard to their cosmological applications.
Testing Strong-Field General Relativity with Black Holes

Tim Johannsen

October 04, 2012

PIRSA:12100049
A Higgs but no sparticles yet: what it means for the (p)MSSM

Ahmed Ismail University of Pittsburgh
October 02, 2012

PIRSA:12100052
High Energy Physics
The phenomenological Minimal Supersymmetric Standard Model (pMSSM) provides a broad perspective on supersymmetric phenomenology. We have generated two large sets of pMSSM models with neutralino and gravitino LSPs, with sparticle masses extending up to 4 TeV. In this talk, I will discuss the implications of searches for supersymmetry and the Higgs, with particular attention to naturalness. In particular, we find that while sparticle spectra with moderately light stops are still allowed, such stops are difficult to find experimentally because of a wide array of possible cascade decays.
Homogeneous and Isotropic Universe from Nonlinear Massive Gravity

A. Emir Gumrukcuoglu
October 02, 2012

PIRSA:12100002
Astrophysics
The question of finite range gravity, or equivalently, whether graviton can have a non-zero mass, has been one of the major challenges in classical field theory for the last 70 years. Generically, a massive gravity theory contains an extra degree in addition to the 5 polarizations of massive graviton, which turns out to be a ghost. Recently, de Rham, Gabadadze and Tolley constructed a nonlinear theory of massive gravity, which successfully eliminates the ghost. Moreover, the theory has also phenomenological relevance, since the graviton mass may account for the accelerated expansion of the present universe, providing an alternative to dark energy. I will present self-accelerating cosmological solutions in the framework of this theory. The cosmological perturbations around these backgrounds have an interesting behavior: instead of the 5 degrees of freedom expected from a massive spin-2 field, only the 2 gravity wave polarizations are dynamical, at linear level. However, nonlinear analysis of the extra modes reveal the existence of ghost instabilities. This implies that a consistent universe solution in this theory should be inhomogeneous and/or anisotropic.
New Observations about the Renormalization Group Flow

Zohar Komargodski Stony Brook University
September 26, 2012

PIRSA:12090058
High Energy Physics
We review recent breakthroughs in understanding some general features of the Renormalization Group and of Quantum Field Theory. We discuss some applications of these new results and their deep connection to the entanglement of the Quantum Field Theory vacuum.
Large-N Collective Fields and de Sitter / CFT correspondence

Sumit Das University of Kentucky
September 25, 2012

PIRSA:12090045
General Relativity & Quantum Cosmology

High Energy Physics
We derive the collective theory of singlet fields of large-N Sp(N) spin models and display its unconventional features. Using the known relationship between O(N) collective fields and higher spin fields of Vasiliev theory in AdS space, we argue that the unique features of the Sp(N) collective theory suggest an interpretation in terms of a higher spin theory in de Sitter space, as proposed by Anninos, Hartman and Strominger. This is reminiscent of the way the Liouville mode is naturally interpreted as time in supercritical worldsheet string theory.
Supermassive black holes in non-spherical galactic nuclei and enhanced rates of star capture events

Eugene Vasiliev Rochester Institute of Technology
September 25, 2012

PIRSA:12090064
Astrophysics
We consider the stellar-dynamical processes which lead to the capture or tidal disruption of stars by a supermassive black hole, review the standard theory of two-body relaxation and loss-cone repopulation in spherical galactic nuclei, and extend it to the axisymmetric and triaxial nuclear star clusters. In the absense of symmetry which conserves angular momentum, the orbits of stars experience regular or chaotic changes of angular momentum even in the smooth potential of star cluster, which creates a substantial population of "centrophilic" orbits. We discuss the loss cone draining rates, i.e. rates of capture of stars from these orbits. Next we consider the relaxation phenomena in non-spherical nuclei, focusing on the differences between spherical, axisymmetric and triaxial cases. It turns out that the rates of repopulation of the loss cone are moderately higher in non-spherical systems, but in the triaxial case an additional, often substantial, increase of capture rates comes from draining of the centrophilic orbit population.
A generalization of Kochen-Specker sets

Laura Mancinska Institute for Quantum Computing (IQC)

September 24, 2012

PIRSA:12090073

I will discuss two generalizations of Kochen-Specker (KS) sets: projective KS sets and generalized KS sets. We will see that projective KS sets can be used to characterize all graphs for which the chromatic number is strictly larger than the quantum chromatic number. Here, the quantum chromatic number is defined via a nonlocal game based on graph coloring. We will further show that from any graph with separation between these two quantities, one can construct a classical channel for which entanglement assistance increases the one-shot zero-error capacity. As an example, we will consider a new family of classical channels with an exponential increase.
Effect of thermal fluctuations in topological p-wave superconductors

Bela Bauer Microsoft Corporation
September 21, 2012

PIRSA:12090039
Condensed Matter
In this talk, I will present our recent work on the effect of thermal fluctuations on the topological stability of chiral p-wave superconductors. We consider two models of superconductors: spinless and spinful with a focus on topological properties and Majorana zero-energy modes. We show that proliferation of vortex-antivortex pairs above the Kosterlitz-Thouless temperature T_KT drives the transition from a thermal Quantum Hall insulator to a thermal metal/insulator, and dramatically modifies the ground-state degeneracy splitting. This shows that in order to utilize 2D chiral p-wave superconductors for topological quantum computing, the temperature should be much smaller than T_KT. Within the spinful chiral p-wave model, we also investigate the interplay between half-quantum vortices carrying Majorana zero-energy modes and full-quantum vortices having trivial topological charge, and discuss topological properties of half-quantum vortices in the background of proliferating full-quantum vortices.
The Higgs Boson and speculative particle physics

Mark Wise California Institute of Technology (Caltech)

September 19, 2012

PIRSA:12090065

The crucial role that the Higgs boson plays in the standard model for strong weak and electromagnetic interactions is reviewed. Recently a resonance with properties consistent with those expected for the Higgs boson has been discovered at the large hadron collider (LHC). This discovery constrains speculations about new physics beyond what is in the standard model. The motivation for such new physics, at roughly the energy scale probed by LHC experiments, and the nature of the constraints imposed by the recent LHC results are discussed.
Jet Substructure, by Accident

Eder Izaguirre LinkedIn (United States)
September 18, 2012

PIRSA:12090063
High Energy Physics
The LHC detectors are allowing experimentalists to look "inside" of jets and study the properties of these. Jet substructure gives us the tools to study boosted resonances that decay into jets. In this talk, I will discuss an extension of substructure techniques to beyond the Standard Model signals where reconstructing resonances may not be optimal, but these techniques still allow us to pick out these signals from a busy QCD environment.

Title	Speaker(s)	Date	Talk Type	Info link
Voids in the SDSS: from demography to cosmology	Paul Sutter	2012-10-09	Scientific Series	View details
Scalars with Higher Derivatives in Supergravity and Cosmology	Jean-Luc Lehners	2012-10-09	Scientific Series	View details
Testing Strong-Field General Relativity with Black Holes	Tim Johannsen	2012-10-04	Scientific Series	View details
A Higgs but no sparticles yet: what it means for the (p)MSSM	Ahmed Ismail	2012-10-02	Scientific Series	View details
Homogeneous and Isotropic Universe from Nonlinear Massive Gravity	A. Emir Gumrukcuoglu	2012-10-02	Scientific Series	View details
New Observations about the Renormalization Group Flow	Zohar Komargodski	2012-09-26	Scientific Series	View details
Large-N Collective Fields and de Sitter / CFT correspondence	Sumit Das	2012-09-25	Scientific Series	View details
Supermassive black holes in non-spherical galactic nuclei and enhanced rates of star capture events	Eugene Vasiliev	2012-09-25	Scientific Series	View details
A generalization of Kochen-Specker sets	Laura Mancinska	2012-09-24	Scientific Series	View details
Effect of thermal fluctuations in topological p-wave superconductors	Bela Bauer	2012-09-21	Scientific Series	View details
The Higgs Boson and speculative particle physics	Mark Wise	2012-09-19	Scientific Series	View details
Jet Substructure, by Accident	Eder Izaguirre	2012-09-18	Scientific Series	View details

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Voids in the SDSS: from demography to cosmology

Scalars with Higher Derivatives in Supergravity and Cosmology

Testing Strong-Field General Relativity with Black Holes

A Higgs but no sparticles yet: what it means for the (p)MSSM

Homogeneous and Isotropic Universe from Nonlinear Massive Gravity

New Observations about the Renormalization Group Flow

Large-N Collective Fields and de Sitter / CFT correspondence

Supermassive black holes in non-spherical galactic nuclei and enhanced rates of star capture events

A generalization of Kochen-Specker sets

Effect of thermal fluctuations in topological p-wave superconductors

The Higgs Boson and speculative particle physics

Jet Substructure, by Accident

Voids in the SDSS: from demography to cosmology

Scalars with Higher Derivatives in Supergravity and Cosmology

Testing Strong-Field General Relativity with Black Holes

A Higgs but no sparticles yet: what it means for the (p)MSSM

Homogeneous and Isotropic Universe from Nonlinear Massive Gravity

New Observations about the Renormalization Group Flow

Large-N Collective Fields and de Sitter / CFT correspondence

Supermassive black holes in non-spherical galactic nuclei and enhanced rates of star capture events

A generalization of Kochen-Specker sets

Effect of thermal fluctuations in topological p-wave superconductors

The Higgs Boson and speculative particle physics

Jet Substructure, by Accident