Scientific Series

Displaying 3061 - 3072 of 5012

New strong interactions and the t t-bar asymmetry

Joachim Brod
University of Cincinnati
May 13, 2014

PIRSA:14050092
Particle Physics
Random models of inflation

Andrew Liddle
University of Lisbon
May 13, 2014

PIRSA:14050007
Cosmology
The quest for self-correcting quantum memory

Olivier Landon-Cardinal
California Institute of Technology
May 12, 2014

PIRSA:14050028
Quantum Information
Curvature in Noncommutative Geometry

masoud khalkhali
Western University
May 09, 2014

PIRSA:14050064
Mathematical physics
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases

Jennifer Cano
University of California System
May 09, 2014

PIRSA:14050011
Condensed Matter
On the role of the extra kinetic term coupling ƛ in classical Hořava-Lifshitz gravity

Luis Pires
Radboud Universiteit Nijmegen
May 08, 2014

PIRSA:14050061
Quantum Gravity
Black holes without Lorentz symmetry

Thomas Sotiriou
University of Nottingham
May 08, 2014

PIRSA:14050002
Strong Gravity
Scattering of emerging excitations in Matrix Product States

Jutho Haegeman
Ghent University
May 06, 2014

PIRSA:14050010
Condensed Matter
Anomalies of discrete symmetries and Symmetry Protected Topological Phases

Anton Kapustin
California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy
May 06, 2014

PIRSA:14050035
Quantum Fields and Strings
Noncommutative geometry and the symmetries of the standard model

Fedele Lizzi
University of Naples Federico II
May 06, 2014

PIRSA:14050031
Particle Physics

Cosmology
The Case for an Alternative Cosmology

Jayant Narlikar
IUCAA - The Inter-University Centre for Astronomy and Astrophysics
May 06, 2014

PIRSA:14050034
Cosmology
John Paul Robinson: Art, Science and Myth

May 02, 2014

PIRSA:14050062

New strong interactions and the t t-bar asymmetry

Joachim Brod
University of Cincinnati
May 13, 2014

PIRSA:14050092
Particle Physics
The CDF and D0 experiments at Tevatron measure a top-quark forward-backward
asymmetry significantly larger than the standard-model prediction.
We construct a model that involves new strong interactions at the electroweak scale
and can explain the measured asymmetry. Our model possesses a flavor symmetry
which allows to evade flavor and collider constraints, while it still permits flavor-violating
couplings of order 1 which are needed to generate the asymmetry via light t-channel vectors.
Random models of inflation

Andrew Liddle
University of Lisbon
May 13, 2014

PIRSA:14050007
Cosmology
Rather than writing down specific functional forms, one can generate inflation models via stochastic processes in order to explore generic properties of inflation models. I describe our explorations of the phenomenology of randomly-generated multi-field inflation models, both for canonical fields and for a braneworld-motivated scenario. Implications of some recent observational results, including BICEP2, will be discussed.
The quest for self-correcting quantum memory

Olivier Landon-Cardinal
California Institute of Technology
May 12, 2014

PIRSA:14050028
Quantum Information
A self-correcting quantum memory is a physical system whose quantum state can be preserved over a long period of time without the need for any external intervention. The most promising candidates are topological quantum systems which would protect information encoded in their degenerate groundspace while interacting with a thermal environment. Many models have been suggested but several approaches have been shown to fail due to no-go results of increasingly general scope. In a nutshell, 2D topological models and many 3D topological models have point-like excitations which propagate freely and change the groundstate at any non-zero temperature. A recent suggestion is to introduce effective long-range interactions between those point-like excitations. In this presentation, I will first explain the desiderata for self-correction, review the recent advances and no-go results, and describe the current endeavours to define a self-correcting system in 2D and 3D. Time permitting, I will briefly present our recent work on the thermal instability of models which aim to introduce effective long-range interactions between point-like excitations (joint work with Beni Yoshida, John Preskill and David Poulin).
Curvature in Noncommutative Geometry

masoud khalkhali
Western University
May 09, 2014

PIRSA:14050064
Mathematical physics
After the seminal work of Connes and Tretkoff on the Gauss-Bonnet theorem for the noncommutative 2-torus and its extension by Fathizadeh and myself, there have been significant developments in understanding the local differential geometry of these noncommutative spaces equipped with curved metrics. In this talk, I will review a series of joint works with Farzad Fathizadeh in which we compute the scalar curvature for curved noncommutative tori and prove the analogue of Weyl's law and Connes' trace theorem. Our final formula for the curvature matches precisely with the one computed independently by A. Connes and H. Moscovici. I will then report on our recent work on the computation of scalar curvature for noncommutative 4-tori (which involves intricacies due to violation of the Kähler condition). We show that metrics with constant curvature are extrema of the analogue of the Einstein–Hilbert action. A purely noncommutative feature in these works is the appearance of the modular automorphism from Tomita–Takesaki theory of KMS states in the final formulas for the curvature.
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases

Jennifer Cano
University of California System
May 09, 2014

PIRSA:14050011
Condensed Matter
The same bulk two-dimensional topological phase can have multiple distinct, fully-chiral edge phases. We show that this can occur in the integer quantum Hall states at fillings 8 and 12 with experimentally-testable consequences. We also show examples for Abelian fractional quantum Hall states, the simplest examples being at filling fractions 8/7, 12/11, 8/15, 16/5. For all examples, we propose experiments that can distinguish distinct edge phases. Our results are summarized by the observation that edge phases correspond to lattices while bulk phases correspond to genera of lattices. Since there are typically multiple lattices in a genus, there are usually many stable fully chiral edge phases corresponding to the same bulk. We show that fermionic systems can have edge phases with only bosonic low-energy excitations and discuss a fermionic generalization of the relation between bulk topological spins and the central charge. The latter follows from our demonstration that every fermionic topological phase can be represented as a bosonic topological phase, together with some number of filled Landau levels. Our analysis also leads to a simple demonstration that all Abelian topological phases can be represented by a Chern-Simons theory parameterized by a K-matrix.
On the role of the extra kinetic term coupling ƛ in classical Hořava-Lifshitz gravity

Luis Pires
Radboud Universiteit Nijmegen
May 08, 2014

PIRSA:14050061
Quantum Gravity
We study the classical constraint algebra of Hořava-Lifshitz gravity, where due to the breaking of 4d diffeomorphism symmetry, there is a new dimensionless coupling absent in GR and whose role is not yet clear. Starting from two apparently contradictory results, we show how the role of the extra coupling differs between the projectable and non-projectable versions of the theory. In particular, we see how in the latter, it gives rise to a non-trivial constraint algebra, akin to the conditions seen in the CMC gauge of GR.
Black holes without Lorentz symmetry

Thomas Sotiriou
University of Nottingham
May 08, 2014

PIRSA:14050002
Strong Gravity
Our current definition of what a black hole is relies heavily on the assumption that there exists a finite maximum speed of propagation for any signal. Indeed, one is tempted to think that the notion of a black hole has no place in a world with infinitely fast signal propagation. I will use concrete examples from Lorentz-violating gravity theories to demonstrate that this naive expectation is not necessarily true.
Scattering of emerging excitations in Matrix Product States

Jutho Haegeman
Ghent University
May 06, 2014

PIRSA:14050010
Condensed Matter
We review the formalism of matrix product states and one of its recent generalisations which allows to variationally determine the dispersion relation of elementary excitations in generic one-dimensional quantum spin chains. These elementary excitations dominate the low energy effective behaviour of the system. We discuss recent work where we show how we can also describe the effective interaction between these excitations – as mediated by the strongly correlated ground state – and how we can extract the corresponding S matrix. With these two ingredients, we can already build a highly non-trivial low-energy description of any microscopic Hamiltonian by assuming that higher order scattering processes are negligible. This allows to extract accurate information about the behaviour of the system under perturbations or at finite temperature, as we illustrate using the spin 1 Heisenberg model.
Anomalies of discrete symmetries and Symmetry Protected Topological Phases

Anton Kapustin
California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy
May 06, 2014

PIRSA:14050035
Quantum Fields and Strings
There is a close connection between Symmetry Protected Topological Phases and anomalies: a surface of an SPT phase typically has a global symmetry with a nonvanishing 't Hooft anomaly which is canceled by the anomaly inflow from the bulk. This observation together with the known results about the classification of SPT phases suggest that anomalies are much more ubiquitous than thought previously and do not require chiral fermions We elucidate the physical mechanism of anomalies and give examples of bosonic theories with 't Hooft anomalies in various dimensions.
Noncommutative geometry and the symmetries of the standard model

Fedele Lizzi
University of Naples Federico II
May 06, 2014

PIRSA:14050031
Particle Physics

Cosmology
I will describe Connes approach to the standard model based on spectral noncommutative geometry with particular emphasis on the symmetries. The model poses constraints which are satisfied by the standard model group, and does not leave much room for other possibilities. There is however a possibility for a larger symmetry (the ``grand algebra'') which may also be instrumental to obtain the correct mass of the Higgs.
The Case for an Alternative Cosmology

Jayant Narlikar
IUCAA - The Inter-University Centre for Astronomy and Astrophysics
May 06, 2014

PIRSA:14050034
Cosmology
This talk will describe the Quasi-Steady State Cosmology proposed in 1993 by Fred Hoyle, Geoffrey Burbidge and Jayant Narlikar. Starting with the motivation for this exercise, a formal field theoretic framework inspired by Mach’s principle is shown to lead to this model. The model is a generalization of the classical steady state model in the sense that it is driven by a scalar field which causes creation in explosive form. Such ‘minicreation events’ lead to a universe with a long term de Sitter expansion superposed with oscillations of shorter time scales. It is shown that this cosmology explains all the observed cosmological features and that there exist potential tests to distinguish between this cosmology and the standard big bang cosmology.
John Paul Robinson: Art, Science and Myth

May 02, 2014

PIRSA:14050062

Canadian glass artist and Renaissance man, John Paul Robinson, explores the mythic potential of science. Explaining that, “This is the idea that scientific discovery is changing our mythology by changing our understanding of the world and our place in it.” Backed with a firm understanding of the science he references, his sculptures poetically interpret such theoretical phenomena as wave particles, string mathematics and black holes. Most people, especially scientists see mythology and science as mutually exclusive and many believe that a scientific understanding of the world will eventually eliminate the need for myth. This idea is based on a misunderstanding as to what myth really is and it’s relationship to science. Myth is not superstition, fairy tail or lies nor is it truth, history or fact. Myth is Art. Myth is a picture, a story, a map; we use to navigate the world. Not the external material world but the world we all create and hold in our minds. In every human mind is a mythic picture of the world that provides the stage for all we experience. This picture not only helps us navigate our world but also performs the critical function of informing our sense of place and belonging within that world. Science cannot replace myth but it can inform it for mythology deals not with the mysteries generated by our ignorance of how the world works but by our understanding of how the world works. The mathematics of string theory is a powerful tool to describe the world but even physicists have to close their eyes and picture in their minds the world their equations are describing. The equation is pure logic and reason, but the picture of tiny strings playing the music that creates the universe is pure mythology. Award-winning glass artist and instructor John Paul Robinson was educated at the Georgian College of Arts and Technology in Barrie, Ontario, and the Ontario College of Art, where he subsequently taught for a number of years. His work has been exhibited in solo shows throughout Canada and the United States, in cities such as Montreal, Toronto and Chicago. Robinson’s works are held in the collections of The Museum of Civilization in Ottawa, Ontario, the Museum of American Glass in Millville, New Jersey and the Musée des Beaux-arts de Montréal, Québec. He has also created the Amber Archive, an annual participatory art project to communicate our existence and creative endeavours (by artists, designers and scientists) to beings millions of years in the future.

Title	Speaker(s)	Date	Talk Type	Info link
New strong interactions and the t t-bar asymmetry	Joachim Brod	2014-05-13	Scientific Series	View details
Random models of inflation	Andrew Liddle	2014-05-13	Scientific Series	View details
The quest for self-correcting quantum memory	Olivier Landon-Cardinal	2014-05-12	Scientific Series	View details
Curvature in Noncommutative Geometry	masoud khalkhali	2014-05-09	Scientific Series	View details
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases	Jennifer Cano	2014-05-09	Scientific Series	View details
On the role of the extra kinetic term coupling ƛ in classical Hořava-Lifshitz gravity	Luis Pires	2014-05-08	Scientific Series	View details
Black holes without Lorentz symmetry	Thomas Sotiriou	2014-05-08	Scientific Series	View details
Scattering of emerging excitations in Matrix Product States	Jutho Haegeman	2014-05-06	Scientific Series	View details
Anomalies of discrete symmetries and Symmetry Protected Topological Phases	Anton Kapustin	2014-05-06	Scientific Series	View details
Noncommutative geometry and the symmetries of the standard model	Fedele Lizzi	2014-05-06	Scientific Series	View details
The Case for an Alternative Cosmology	Jayant Narlikar	2014-05-06	Scientific Series	View details
John Paul Robinson: Art, Science and Myth		2014-05-02	Scientific Series	View details

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