Scientific Series

Displaying 3001 - 3012 of 5012

Maximal supergravity, holography and the Romans mass

Oscar Varela
Harvard University
September 12, 2014

PIRSA:14090071
Quantum Fields and Strings
Stripes and pairing in t-J and Hubbard models

Steven White
University of California, Irvine
September 11, 2014

PIRSA:14090074
Condensed Matter
Force-Free Electrodynamics around Extreme Kerr Black Holes

Maria J. Rodriguez
Utah State University
September 11, 2014

PIRSA:14090065
Strong Gravity
An invariant of topologically ordered states under local unitary transformations

Jeongwan Haah
Massachusetts Institute of Technology (MIT) - Department of Physics
September 10, 2014

PIRSA:14090030
Quantum Information
Short-Range Entangled Phases and Topology

Anton Kapustin
California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy

September 10, 2014

PIRSA:14090002
Many-Body Localization in translation invariant systems?

Francois Huveneers
University of Paris-Saclay

September 09, 2014

PIRSA:14090027
Firewalls- A GR perspective

Bill Unruh
University of British Columbia
September 04, 2014

PIRSA:14090066
Quantum Gravity
Monogamy of entanglement and improved mean-field ansatz for spin lattices

Ralf Schuetzhold
Helmholtz-Zentrum Dresden-Rossendorf
September 02, 2014

PIRSA:14090069
Condensed Matter
Asymmetric Dark Matter Bound States

Mark Wise
California Institute of Technology (Caltech)

September 02, 2014

PIRSA:14090068
Black hole evaporation without firewalls

James Bardeen
September 02, 2014

PIRSA:14090001
Cosmology
Coloron-assisted Leptoquarks at the LHC

Joshua Berger
Cornell University
August 29, 2014

PIRSA:14080042
Particle Physics
The Gravity Dual of Supersymmetric Gauge Theories on a Squashed Five-Sphere

Martin Fluder
University of Oxford

August 26, 2014

PIRSA:14080003

Maximal supergravity, holography and the Romans mass

Oscar Varela
Harvard University
September 12, 2014

PIRSA:14090071
Quantum Fields and Strings
At large N, an important sector of the ABJM field theory defined on a stack of N M2-branes can be described holographically by the D=4 N=8 SO(8)-gauged supergravity of de Wit and Nicolai. Since its inception, the latter has been tacitly assumed to be unique. Recently, however, a one-parameter family of SO(8) gaugings of N=8 supergravity has been discovered, the de Wit-Nicolai theory being just a member in this class. I will explain how this overlooked family of SO(8)-gauged supergravities is deeply related to electric/magnetic duality breaking in four dimensions. I will then discuss some predictions that can be made about the family of dual large-N field theories that these supergravities define, focusing on the structure of superconformal phases and the RG flows between them. I will finally argue that when the gauging is chosen to be related, but different, to the SO(8) one, the D=4 N=8 family arises as consistent truncation of massive IIA on the six-sphere, with the Romans mass identified as the electric/magnetic duality-breaking parameter.
Stripes and pairing in t-J and Hubbard models

Steven White
University of California, Irvine
September 11, 2014

PIRSA:14090074
Condensed Matter
This has been a leading question in condensed matter physics since the discovery of the cuprate superconductors. In this talk I will review some of the DMRG and tensor network results for the ground states of these models. A key question I'll address is the issue of stripes: are the ground states striped? Do stripes compete with or induce d-wave superconductivity? Another question I'll address is: how well does 2D DMRG do in comparison with iPEPS and quantum Monte Carlo. I will also show recent results for a standard 3-band Hubbard model for the cuprates. The asymmetry between hole and electron doped systems which is seen in the cuprates arises naturally from this model.
Force-Free Electrodynamics around Extreme Kerr Black Holes

Maria J. Rodriguez
Utah State University
September 11, 2014

PIRSA:14090065
Strong Gravity
Plasma-filled magnetospheres can extract energy from a spinning black hole and provide the power source for a variety of observed astrophysical phenomena. These magnetospheres are described by the highly nonlinear equations of force-free electrodynamics, or FFE. Typically these equations can only be solved numerically. In this talk I will explain how to analytically obtain several infinite families of exact solutions of the full nonlinear FFE equations very near the horizon of a maximally spinning black hole, where the energy extraction takes place.
An invariant of topologically ordered states under local unitary transformations

Jeongwan Haah
Massachusetts Institute of Technology (MIT) - Department of Physics
September 10, 2014

PIRSA:14090030
Quantum Information
For an anyon model in two spatial dimensions described by a modular tensor category, the topological S-matrix encodes the mutual braiding statistics, the quantum dimensions, and the fusion rules of anyons. It is nontrivial whether one can compute the topological S-matrix from a single ground state wave function. In this talk, I will show that, for a class of Hamiltonians, it is possible to define the S-matrix regardless of the degeneracy of the ground state. The definition manifests invariance of the S-matrix under local unitary transformations (quantum circuits). The defined S-matrix depends only on the ground state, in the sense that it can be computed by any Hamiltonian in the class of which the state is a ground state. This property, together with the local unitary invariance implies that any quantum circuit that connects two ground states of distinct topological S-matrices must have depth that is at least linear in the diameter of the system. A higher dimensional analog is straightforward. [arXiv:1407.2926]
Short-Range Entangled Phases and Topology

Anton Kapustin
California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy

September 10, 2014

PIRSA:14090002

Recently a new and rather unexpected connection between condensed matter physics and algebraic topology has been noted. Namely, it appears that phases of matter with an energy gap, no long-range entanglement, and fixed symmetry can be classified using cobordism theory. I will exhibit several examples of this connection and describe a possible explanation.
Many-Body Localization in translation invariant systems?

Francois Huveneers
University of Paris-Saclay

September 09, 2014

PIRSA:14090027

Roughly speaking, Many-Body Localization (MBL) refers to the state of a material that fails to thermalize. Though MBL has mostly been studied in quenched disordered systems, several authors have recently proposed that this phase could be realized in clean (translation invariant) systems too. In this talk, I will discuss this idea and ask to which extent an MBL phase can indeed be expected in systems without quenched disorder. Hopefully, the discussion shed also some light on the localization-delocalization transition for more generic many-body systems. From joint work with W. De Roeck (Leuven), M. Mueller (Trieste), M. Schiulaz (Trieste).
Firewalls- A GR perspective

Bill Unruh
University of British Columbia
September 04, 2014

PIRSA:14090066
Quantum Gravity
This talk will examine the Firewall argument and a number of possible approaches to it, with a variety of simple examples to try to clarify various aspects of the arguments.
Monogamy of entanglement and improved mean-field ansatz for spin lattices

Ralf Schuetzhold
Helmholtz-Zentrum Dresden-Rossendorf
September 02, 2014

PIRSA:14090069
Condensed Matter
We consider rather general spin-1/2 lattices with large coordination numbers Z.
Based on the monogamy of entanglement and other properties of the concurrence C,
we derive rigorous bounds for the entanglement between neighboring spins,
which show that C decreases for large Z. In addition, the concurrence C measures the deviation from mean-field behavior and can only vanish if the mean-field ansatz yields an exact ground state of the Hamiltonian. Motivated by these findings, we propose an improved mean-field ansatz by adding entanglement
Asymmetric Dark Matter Bound States

Mark Wise
California Institute of Technology (Caltech)

September 02, 2014

PIRSA:14090068

One of the simplest low energy effective theories with Asymmetric Dark Matter contains a gauge singlet Dirac Fermion for the dark matter and a gauge singlet scalar as the mediator that the dark matter decays into. In this model I discuss the spectrum of bound states (two body and multi-body) and the cosmological production/dissociation of dark matter two body bound states.
Black hole evaporation without firewalls

James Bardeen
September 02, 2014

PIRSA:14090001
Cosmology
There need not be any conflict between unitarity, locality, and regularity of the horizon in black hole evaporation. I discuss a scenario in which the initial collapse that forms the black hole results in a small non-singular core inside an inner event horizon. This core grows as the result of quantum back-reaction associated with the increasing entanglement entropy of Hawking radiation quanta and their partners trapped inside the core. By the Page time the inner and outer apparent horizons either merge into a degenerate horizon, shutting off the Hawking radiation and leaving a massive remnant, or they disappear completely, allowing the trapped quantum information to escape. The scenario is justified by appeals to the Bousso covariant entropy bound and the ER=EPR conjecture. The talk is largely based on arxiv.org/1406.4098.
Coloron-assisted Leptoquarks at the LHC

Joshua Berger
Cornell University
August 29, 2014

PIRSA:14080042
Particle Physics
Recent searches for a first-generation leptoquark by the CMS collaboration have shown around 2.5 sigma deviations from Standard Model predictions in both the eejj and e nu jj channels. Furthermore, the eejj invariant mass distribution has another 2.8 sigma excess from the CMS right-handed W plus heavy neutrino search. We point out that additional leptoquark production from a heavy coloron decay can provide a good explanation for all three excesses. The coloron has a mass around 2.1 TeV and the leptoquark mass can vary from 550 GeV to 650 GeV. A key prediction of this model is an edge in the total m_T distribution of e nu jj events at around 2.1 TeV.
The Gravity Dual of Supersymmetric Gauge Theories on a Squashed Five-Sphere

Martin Fluder
University of Oxford

August 26, 2014

PIRSA:14080003

We construct the gravity duals of large N supersymmetric gauge theories on a squashed five-sphere. They are constructed in Euclidean Romans F(4) gauged supergravity in six-dimensions. We find a one- as well as a two-parameter family of solutions and evaluate the renormalised on-shell and fundamental string action for these solutions to find precise agreement with gauge theory.

Title	Speaker(s)	Date	Talk Type	Info link
Maximal supergravity, holography and the Romans mass	Oscar Varela	2014-09-12	Scientific Series	View details
Stripes and pairing in t-J and Hubbard models	Steven White	2014-09-11	Scientific Series	View details
Force-Free Electrodynamics around Extreme Kerr Black Holes	Maria J. Rodriguez	2014-09-11	Scientific Series	View details
An invariant of topologically ordered states under local unitary transformations	Jeongwan Haah	2014-09-10	Scientific Series	View details
Short-Range Entangled Phases and Topology	Anton Kapustin	2014-09-10	Scientific Series	View details
Many-Body Localization in translation invariant systems?	Francois Huveneers	2014-09-09	Scientific Series	View details
Firewalls- A GR perspective	Bill Unruh	2014-09-04	Scientific Series	View details
Monogamy of entanglement and improved mean-field ansatz for spin lattices	Ralf Schuetzhold	2014-09-02	Scientific Series	View details
Asymmetric Dark Matter Bound States	Mark Wise	2014-09-02	Scientific Series	View details
Black hole evaporation without firewalls	James Bardeen	2014-09-02	Scientific Series	View details
Coloron-assisted Leptoquarks at the LHC	Joshua Berger	2014-08-29	Scientific Series	View details
The Gravity Dual of Supersymmetric Gauge Theories on a Squashed Five-Sphere	Martin Fluder	2014-08-26	Scientific Series	View details

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