Scientific Series

Displaying 3481 - 3492 of 5007

Parameterizing dark sector perturbations

Jonathan Pearson Durham University
January 15, 2013

PIRSA:13010019
Astrophysics
Exotic topological order from quantum fractal code

Beni Yoshida Perimeter Institute for Theoretical Physics
January 14, 2013

PIRSA:13010101
Quantum Physics
New transport properties of holographic superfluids

Daniel Fernandez University of Iceland
January 10, 2013

PIRSA:13010004
General Relativity & Quantum Cosmology
Field-induced thermal transport in BEC antiferromagnets

Alexander Chernyshev University of California, Irvine
January 08, 2013

PIRSA:13010002
Condensed Matter
Worldsheet form factors in AdS/CFT

Tristan McLoughlin Trinity College Dublin
January 08, 2013

PIRSA:13010022
High Energy Physics
Fifth forces and new particles from dark energy

Amol Upadhye University of Wisconsin–Madison
January 08, 2013

PIRSA:13010023
Astrophysics
All one-loop amplitudes in N=6 Chern-Simons matter theories

Congkao Wen Queen Mary University of London
December 18, 2012

PIRSA:12120005
High Energy Physics
Fermionic toric code model and a new class of topological phases in interacting fermion system

Zheng-Cheng Gu Chinese University of Hong Kong
December 14, 2012

PIRSA:12120037
Condensed Matter
Accidental Supersymmetry and the Renormalization of Co-dimension 2 Branes

Matthew Williams PROTO Manufacturing (Canada)
December 14, 2012

PIRSA:12120039
High Energy Physics
Black holes: To be or not be, that is the question

Luis Garay Complutense University of Madrid
December 13, 2012

PIRSA:12120032
General Relativity & Quantum Cosmology
Adventures with Monte Carlo Simulations of the Self-Avoiding Walk

Esaias Janse van Rensburg York University

December 12, 2012

PIRSA:12120025
Quantum Chaos, Information Gain and Quantum Tomography.

Vaibhav Madhok Wilfrid Laurier University
December 11, 2012

PIRSA:12120036
Quantum Physics

Parameterizing dark sector perturbations

Jonathan Pearson Durham University
January 15, 2013

PIRSA:13010019
Astrophysics
When recent observational evidence and the GR+FRW+CDM model are combined we obtain the result that the Universe is accelerating, where the acceleration is due to some not-yet-understood "dark sector". There has been a considerable number of theoretical models constructed in an attempt to provide an "understanding" of the dark sector: dark energy and modified gravity theories. The proliferation of modified gravity and dark energy models has brought to light the need to construct a "generic" way to parameterize the dark sector. We will discuss our new way of approaching this problem, looking at linearised perturbations. Our approach is inspired by that taken in particle physics, where the most general modifications to the standard model are written down for a given field content that is compatible with some assumed symmetry (which we take to be isotropy of the background spatial sections). Our emphasis is on constructing a theoretically motivated toolkit which can be used to extract meaningful information about the dark sector (such as its field content). We find, for example, that the observational impact of very broad classes of theories can be encoded by a very small (less than 5) number of parameters. It is these parameters which we hope to measure with observational data.
Exotic topological order from quantum fractal code

Beni Yoshida Perimeter Institute for Theoretical Physics
January 14, 2013

PIRSA:13010101
Quantum Physics
We present a family of three-dimensional local quantum codes with pairs of fractal logical operators. It has two polynomials over finite fields as input parameters which generate fractal shapes of anti-commuting logical operators, and possesses exotic topological order with quantum glassiness which is beyond descriptions of conventional topological field theory. A necessary and sufficient condition for being free from string-like logical operators is obtained under which the model works as marginally self-correcting quantum memory. We also provide theoretical tools to analyze physical and coding properties of translation symmetric stabilizer Hamiltonians.
New transport properties of holographic superfluids

Daniel Fernandez University of Iceland
January 10, 2013

PIRSA:13010004
General Relativity & Quantum Cosmology
In the context of holography applied to condensed matter theory, I will present an analysis of transport properties of p-wave superfluids by means of a gravity dual. Fluctuations modes in the SU(2) Einstein-Yang-Mills theory are considered, and phenomenological implications are derived. Due to the spatial anisotropy of the system, a non-universal shear viscosity is obtained, along with a new coefficient associated to normal stress differences. I will also discuss how the transport phenomena in this model is related to the thermoelectric, flexoelectric and piezoelectric effects (mixing of electric current, heat flux and mechanical stress), which have been observed in some superconductors and crystal liquids.
Field-induced thermal transport in BEC antiferromagnets

Alexander Chernyshev University of California, Irvine
January 08, 2013

PIRSA:13010002
Condensed Matter
Recent experiments in BEC quantum magnets exhibit a dramatic evolution of the thermal conductivity of these materials in magnetic field. By considering various relaxation mechanisms of bosonic excitations in the vicinity of the BEC quantum-critical point at finite temperature we provide a detailed explanation of several unusual features of the data. We identify the leading impurity-scattering interaction and demonstrate that its renormalization due to quantum fluctuations of the paramagnetic state compensates the related mass renormalization effect. This explains the enigmatic absence of the asymmetry between the two critical points in the low-T thermal conductivity data, while such an asymmetry is prominent in many other physical quantities. The observed characteristic "migration'' of the peak in thermal conductivity away from the transition points as a function of temperature is explained as due to a competition between an increase in the number of heat carriers and an enhancement of their mutual scattering. An important role of the three-boson scattering processes within the ordered phase of these systems is also discussed. Other qualitative and quantitative features of the experiment are clarified and the future directions are sketched.
Worldsheet form factors in AdS/CFT

Tristan McLoughlin Trinity College Dublin
January 08, 2013

PIRSA:13010022
High Energy Physics
The study of the worldsheet S-matrix for AdS_5×S^5 strings was a key step in the complete determination of the non-pertubrative planar spectrum of anomalous dimensions for N=4 super-Yang-Mills. To go beyond the spectral problem it is important to consider higher-point worldsheet correlation functions and, as is standard in many integrable models, one approach is the study of form factors. We will discuss a set of consistency conditions appropriate to form factors in the light-cone gauge fixed AdS_5×S^5 string theory. We further discuss the form factors in the weakly coupled dual description, verifying that the relevant conditions naturally hold for the one-loop Heisenberg spin-chain.
Fifth forces and new particles from dark energy

Amol Upadhye University of Wisconsin–Madison
January 08, 2013

PIRSA:13010023
Astrophysics
Dark energy coupled to Standard Model fermions and gauge bosons gives rise to fifth forces and new particles, which are readily accessible to experiments from laboratory to cosmological scales. I will discuss chameleon and symmetron models, whose fifth forces are screened locally through large effective masses and symmetry-restoring phase transitions, respectively. Fifth force experiments such as the Eot-Wash torsion balance will test chameleons with small quantum corrections and gravitation-strength fifth forces, as well as symmetrons with coupling energies just beyond the Standard Model scale. A dark energy coupling to electromagnetism would imply that photons passing through a magnetic field will oscillate into particles of dark energy, a phenomenon studied by afterglow experiments such as CHASE. After constraining dark energy using laboratory experiments, I proceed to astrophysical probes. Particles of a photon-coupled dark energy could be produced in the Sun and detected in magnetic helioscopes such as CAST, while fifth forces may alter the dynamics of variable stars and the growth of large-scale structure.
All one-loop amplitudes in N=6 Chern-Simons matter theories

Congkao Wen Queen Mary University of London
December 18, 2012

PIRSA:12120005
High Energy Physics
In this talk we will present results on all one-loop scattering amplitudes in N=6 Chern-Simons matter theories. Especially we will discuss connection between certain triple-cut diagrams and tree-level recursive diagrams, and a general formula capturing the multi-particle factorization of arbitrary one-loop amplitudes in the theories is obtained from this connection. Furthermore a recursion relation for the supercoefficients of one-loop amplitudes will be derived, which leads the solution for all one-loop amplitudes.
Fermionic toric code model and a new class of topological phases in interacting fermion system

Zheng-Cheng Gu Chinese University of Hong Kong
December 14, 2012

PIRSA:12120037
Condensed Matter
Accidental Supersymmetry and the Renormalization of Co-dimension 2 Branes

Matthew Williams PROTO Manufacturing (Canada)
December 14, 2012

PIRSA:12120039
High Energy Physics
In this talk, I'll give a brief summary of how one-loop bulk eﬀects renormalize both bulk and brane eﬀective interactions for geometries sourced by codimension-two branes. I'll then discuss what these results imply for a six-dimensional supergravity model which aims to capture the features that make extra-dimensional physics attractive for understanding naturalness issues in particle physics. I'll also emphasize the role that brane back-reaction plays in yielding unexpected results, and present a one-loop contribution to the 4D vacuum energy whose size is set by the KK scale.
Black holes: To be or not be, that is the question

Luis Garay Complutense University of Madrid
December 13, 2012

PIRSA:12120032
General Relativity & Quantum Cosmology
I will review some problems of the black hole paradigm and explore other
possibilities for the final state of stellar collapse other than an evaporating
black hole. In particular I will use the so-called transplanckian problem as a
guide in this search for a compelling scenario for the evaporation of
ultracompact objects.
Adventures with Monte Carlo Simulations of the Self-Avoiding Walk

Esaias Janse van Rensburg York University

December 12, 2012

PIRSA:12120025

The Rosenbluth Method is a classical kinetic growth Monte Carlo algorithm for growing a self-avoiding walk by appending steps to its endpoint. This algorithm can be generalised by the implementation of more general elementary moves (for example, BFACF elementary moves) to realise kinetic growth algorithms for lattice polygons. This generalises the counting principle that underlies the Rosenbluth method and the result is a widely applicable class of algorithms which may be used for microcanonical sampling in discrete models. In addition to self-avoiding walks, several applications of kinetic growth and canonical Monte Carlo algorithms will be presented, including the sampling of trivial words in abstract groups, as well as knotted lattice polygons and discrete lattice spin systems such as the Potts model. This is work was done in collaboration with Andrew Rechnitzer of the Mathematics Department at the University of British Columbia.
Quantum Chaos, Information Gain and Quantum Tomography.

Vaibhav Madhok Wilfrid Laurier University
December 11, 2012

PIRSA:12120036
Quantum Physics
Quantum chaos is the study of quantum systems whose classical description is chaotic. How does chaos manifest itself in the quantum world? In recent years, attempts have been made to address this question from the perspective of quantum information theory. It is in this spirit that we study the connection between quantum chaos and information gain in the time series of a measurement record used for quantum tomography. The record is obtained as a sequence of expectation values of a Hermitian operator evolving under repeated application of the Floquet operator of the quantum kicked top on a large ensemble of identical systems. We find an increase in information gain and hence higher fidelities in the process when the Floquet maps employed increase in chaoticity. We make predictions for the information gain using random matrix theory in the fully chaotic regime and show a remarkable agreement between the two.

Title	Speaker(s)	Date	Talk Type	Info link
Parameterizing dark sector perturbations	Jonathan Pearson	2013-01-15	Scientific Series	View details
Exotic topological order from quantum fractal code	Beni Yoshida	2013-01-14	Scientific Series	View details
New transport properties of holographic superfluids	Daniel Fernandez	2013-01-10	Scientific Series	View details
Field-induced thermal transport in BEC antiferromagnets	Alexander Chernyshev	2013-01-08	Scientific Series	View details
Worldsheet form factors in AdS/CFT	Tristan McLoughlin	2013-01-08	Scientific Series	View details
Fifth forces and new particles from dark energy	Amol Upadhye	2013-01-08	Scientific Series	View details
All one-loop amplitudes in N=6 Chern-Simons matter theories	Congkao Wen	2012-12-18	Scientific Series	View details
Fermionic toric code model and a new class of topological phases in interacting fermion system	Zheng-Cheng Gu	2012-12-14	Scientific Series	View details
Accidental Supersymmetry and the Renormalization of Co-dimension 2 Branes	Matthew Williams	2012-12-14	Scientific Series	View details
Black holes: To be or not be, that is the question	Luis Garay	2012-12-13	Scientific Series	View details
Adventures with Monte Carlo Simulations of the Self-Avoiding Walk	Esaias Janse van Rensburg	2012-12-12	Scientific Series	View details
Quantum Chaos, Information Gain and Quantum Tomography.	Vaibhav Madhok	2012-12-11	Scientific Series	View details

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Format results

Parameterizing dark sector perturbations

Exotic topological order from quantum fractal code

New transport properties of holographic superfluids

Field-induced thermal transport in BEC antiferromagnets

Worldsheet form factors in AdS/CFT

Fifth forces and new particles from dark energy

All one-loop amplitudes in N=6 Chern-Simons matter theories

Fermionic toric code model and a new class of topological phases in interacting fermion system

Accidental Supersymmetry and the Renormalization of Co-dimension 2 Branes

Black holes: To be or not be, that is the question

Adventures with Monte Carlo Simulations of the Self-Avoiding Walk

Quantum Chaos, Information Gain and Quantum Tomography.

Parameterizing dark sector perturbations

Exotic topological order from quantum fractal code

New transport properties of holographic superfluids

Field-induced thermal transport in BEC antiferromagnets

Worldsheet form factors in AdS/CFT

Fifth forces and new particles from dark energy

All one-loop amplitudes in N=6 Chern-Simons matter theories

Fermionic toric code model and a new class of topological phases in interacting fermion system

Accidental Supersymmetry and the Renormalization of Co-dimension 2 Branes

Black holes: To be or not be, that is the question

Adventures with Monte Carlo Simulations of the Self-Avoiding Walk

Quantum Chaos, Information Gain and Quantum Tomography.