Scientific Series

Displaying 3145 - 3156 of 5090

Physical Hilbert space for the affine group formulation of 4D, gravity of Lorentzian signature.

Eyo Ita US Naval Academy and Cambridge University (DAMTP)
July 31, 2014

PIRSA:14070033
General Relativity & Quantum Cosmology
Asymmetric Hawking Radiation : Baryogenesis from Hawking Radiation

Anson Hook University of Maryland, College Park
July 29, 2014

PIRSA:14070019
High Energy Physics
Space-Time Circuit-to-Hamiltonian construction and Its Applications

Barbara Terhal Delft University of Technology
July 23, 2014

PIRSA:14070031
Quantum Physics
Supersymmetric AdS5 solutions in M-theory and Class S SCFT's

Ibrahima Bah University of Southern California (USC)
July 22, 2014

PIRSA:14070032
High Energy Physics
Inferring causal structure: a quantum advantage

Katja Ried Universität Innsbruck
July 17, 2014

PIRSA:14070021
Quantum Physics
Exploring N=1 theories of class S through Higgsing, dualizing and twisting

Jaewon Song University of California, San Diego
July 15, 2014

PIRSA:14070024
High Energy Physics
Improving Mass Measurements Using Many-Body Phase Space

Can Kilic The University of Texas at Austin
July 15, 2014

PIRSA:14070023
High Energy Physics
Cosmological Coincidence Problem
July 15, 2014

PIRSA:14070030
Astrophysics
Strong majorization entropic uncentainty relations

Karol Zyczkowski Jagiellonian University
July 14, 2014

PIRSA:14070017
Quantum Physics
TBA
July 08, 2014

PIRSA:14070018
Condensed Matter
Numerical investigations of singularities in general relativity

David Garfinkle Oakland University
June 26, 2014

PIRSA:14060052
Astrophysics
On Quantum Tunnelling

Neil Turok University of Edinburgh
June 25, 2014

PIRSA:14060051
Astrophysics

Physical Hilbert space for the affine group formulation of 4D, gravity of Lorentzian signature.

Eyo Ita US Naval Academy and Cambridge University (DAMTP)
July 31, 2014

PIRSA:14070033
General Relativity & Quantum Cosmology
The authors have revealed a fundamental structure which has been hidden within the Wheeler-DeWitt (WDW) constraint of four dimensional General Relativity (GR) of Lorentzian signature in the Ashtekar self-dual variables. The WDW equation can be written as the commutator of two geometric entities, namely the imaginary part of the Chern-Simons functional Q and the local volume element V(x) of 3-space. Upon quantization with cosmological constant, the WDW equation takes on the form of the Lie algebra of the affine group of transformations of the straight line, with Q and V(x) playing the role of the generators for the Lie algebra. The generators are Hermitian, which addresses the issue of the implementation of the reality conditions of GR at the quantum level. Additionally, the irreducible unitary representations (IUR) implement the positivity of the spectrum of the volume operator V(x) at the quantum level This development has led to the existence of elements of the physical Hilbert space for four dimensional gravity of Lorentzian signature, the full theory, in the form of irreducible, unitary representations of the affine group of transformations of the straight line. The affine Lie algebraic structure of the WDW equation remains intact even in the presence of nongravitational fields. This feature has led to the extension of the affine group formulation to elements of the physical Hilbert space for gravity coupled to the full Standard Model of particle physics, quantized on equal footing. Work on the physical interpretation of the states with respect to gauge-diffeomorphism invariant observables, and spacetime geometries solving the Einstein equations is in progress. The journal reference for these results are as follows: - The first result has been published in CQG 30 (2013) 065013 - The second result has just been published in Annals of Physics Journal Vol.343, pages 153-163, April 2014
Asymmetric Hawking Radiation : Baryogenesis from Hawking Radiation

Anson Hook University of Maryland, College Park
July 29, 2014

PIRSA:14070019
High Energy Physics
We show that in the presence of a chemical potential, black hole evaporation generates baryon number. If the inflaton or Ricci scalar is derivatively coupled to the B-L current, the expansion of the universe acts as a chemical potential and splits the energy levels of particles and their anti-particles. The asymmetric Hawking radiation of primordial black holes can thus be used to generate a B-L asymmetry. If dark matter is produced by the same mechanism, the coincidence between the mass density of visible and dark matter can be naturally explained.
Space-Time Circuit-to-Hamiltonian construction and Its Applications

Barbara Terhal Delft University of Technology
July 23, 2014

PIRSA:14070031
Quantum Physics
The circuit-to-Hamiltonian construction translates a dynamics (a quantum circuit and its output) into statics (the groundstate of a circuit Hamiltonian) by explicitly defining a quantum register for a clock. The standard Feynman-Kitaev construction uses one global clock for all qubits while we consider a different construction in which a clock is assigned to each point in space where a qubit of the quantum circuit resides. We show how one can apply this construction to one-dimensional quantum circuits for which the circuit Hamiltonian realizes the dynamics of a vibrating string. We discuss how the construction can be used (1) in quantum complexity theory to obtain new and stronger results in QMA and (2) how one can realize, based on this construction, universal quantum adiabatic computation and a universal quantum walk using a 2D interacting particle Hamiltonian. See http://arxiv.org/abs/1311.6101
Supersymmetric AdS5 solutions in M-theory and Class S SCFT's

Ibrahima Bah University of Southern California (USC)
July 22, 2014

PIRSA:14070032
High Energy Physics
We provide a framework for describing gravity duals of four-dimensional N=1 superconformal field theories obtained by compactifying a stack of M5-branes on a Riemann surface. The gravity solutions are completely specified by two scalar potentials whose pole structures on the Riemann surface correspond to the spectrum of punctures that labels different theories. We discuss how to identify these puncture in gravity.
Inferring causal structure: a quantum advantage

Katja Ried Universität Innsbruck
July 17, 2014

PIRSA:14070021
Quantum Physics
A fundamental question in trying to understand the world -- be it classical or quantum -- is why things happen. We seek a causal account of events, and merely noting correlations between them does not provide a satisfactory answer. Classical statistics provides a better alternative: the framework of causal models proved itself a powerful tool for studying causal relations in a range of disciplines. We aim to adapt this formalism to allow for quantum variables and in the process discover a new perspective on how causality is different in the quantum world. Causal inference is a central task in the context of causal models: given observed statistics over a set of variables, one aims to infer how they are causally related. Yet in the seemingly simple case of just two classical variables, this is impossible (unless one makes additional assumptions). I will show how the analogous task for quantum variables can be solved. This quantum advantage is reminiscent of the advantages that quantum mechanics offers in computing and communication, and may lead to similarly rich insights. Our scheme is corroborated by data obtained in collaboration with Kevin Resch's experimental group. Time permitting, I will also address other applications of the quantum causal models. arXiv:1406.5036
Exploring N=1 theories of class S through Higgsing, dualizing and twisting

Jaewon Song University of California, San Diego
July 15, 2014

PIRSA:14070024
High Energy Physics
We study a class of 4d N=1 SCFTs obtained from partial compactifications of 6d N=(2, 0) theory on a Riemann surface with punctures. We identify theories corresponding to curves with general type of punctures through nilpotent Higgsing and Seiberg dualities. The `quiver tails' of N=1 class S theories turn out to differ significantly from N=2 counterpart and have interesting properties. Various dual descriptions for such a theory can be found by using colored pair-of-pants decompositions. Especially, we find N=1 analog of Argyres-Seiberg duality for the SQCD with various gauge groups. We compute anomaly coefficients and superconformal indices to verify our proposal.
Improving Mass Measurements Using Many-Body Phase Space

Can Kilic The University of Texas at Austin
July 15, 2014

PIRSA:14070023
High Energy Physics
After the 7 and 8 TeV LHC runs, we have no conclusive evidence of physics beyond the Standard Model, leading us to suspect that even if new physics is discovered during run II, the number of signal events may be limited, making it crucial to optimize measurements for the case of low statistics. I will argue that phase space correlations between subsequent on-shell decays in a cascade contain additional information compared to commonly used kinematic variables, and this can be used to significantly improve the precision and accuracy of mass measurements. The improvement is connected to the properties of the volume element of many-body phase space, and is particularly relevant to the case of low signal statistics.
Cosmological Coincidence Problem
July 15, 2014

PIRSA:14070030
Astrophysics
I will try to explain how cosmological coincidence of the two values, the matter energy density and the dark energy density, at the present epoch based on a single scalar field model whith a quartic potential, non-mimimally interacting with gravity. Dark energy in this model originates from the potential energy of the scalar field, which is sourced by the appearance of non-relativistic matter at the time z~ 10^10. No fine tuning of parameter are neccessary.
Strong majorization entropic uncentainty relations

Karol Zyczkowski Jagiellonian University
July 14, 2014

PIRSA:14070017
Quantum Physics
We analyze entropic uncertainty relations in a finite dimensional Hilbert space and derive several strong bounds for the sum of two entropies obtained in projective measurements with respect to any two orthogonal bases. We improve the recent bounds by Coles and Piani, which are known to be stronger than the well known result of Maassen and Uffink. Furthermore, we find a novel bound based on majorization techniques, which also happens to be stronger than the recent results involving largest singular values of submatrices of the unitary matrix connecting both bases. The first set of new bounds give better results for unitary matrices close to the Fourier matrix, while the second one provides a significant improvement in the opposite sectors. Some results derived admit generalization to arbitrary mixed states, so that corresponding bounds are increased by the von Neumann entropy of the measured state. The majorization approach is finally extended to the case of several measurements.
TBA
July 08, 2014

PIRSA:14070018
Condensed Matter
Numerical investigations of singularities in general relativity

David Garfinkle Oakland University
June 26, 2014

PIRSA:14060052
Astrophysics
The singularity theorems of general relativity tell us that spacetime singularities form in gravitational collapse, but tell us very little about the precise nature of these singularities. More information can be found using analytic approximations and numerical simulations. It is conjectured that inside black holes are two types of singularities: one that is spacelike, local, and oscillatory, and the other that is null and weak. This talk will review what numerical simulations of singularities have been done and the extent to which the above conjecture has been verified by the simulations.
On Quantum Tunnelling

Neil Turok University of Edinburgh
June 25, 2014

PIRSA:14060051
Astrophysics
One of the most basic but intriguing properties of quantum systems is their ability to `tunnel' between configurations which are classically disconnected. That is, processes which are classically impossible, are quantum allowed. In this talk I will outline a new, first-principles approach combining the semiclassical approximation with the concepts of post-selection and weak measurement. Its main virtue is to provide a real-time description within which sharp answers can be given to questions such as 'how long did the tunneling take' and 'where was the particle while it was tunneling?' Potential applications span a vast range, from laboratory tests to understanding black hole evaporation, the stability of the electroweak Higgs vacuum and the future of our universe, and the validity (or otherwise) of the "inflationary multiverse" scenario.

Title	Speaker(s)	Date	Talk Type	Info link
Physical Hilbert space for the affine group formulation of 4D, gravity of Lorentzian signature.	Eyo Ita	2014-07-31	Scientific Series	View details
Asymmetric Hawking Radiation : Baryogenesis from Hawking Radiation	Anson Hook	2014-07-29	Scientific Series	View details
Space-Time Circuit-to-Hamiltonian construction and Its Applications	Barbara Terhal	2014-07-23	Scientific Series	View details
Supersymmetric AdS5 solutions in M-theory and Class S SCFT's	Ibrahima Bah	2014-07-22	Scientific Series	View details
Inferring causal structure: a quantum advantage	Katja Ried	2014-07-17	Scientific Series	View details
Exploring N=1 theories of class S through Higgsing, dualizing and twisting	Jaewon Song	2014-07-15	Scientific Series	View details
Improving Mass Measurements Using Many-Body Phase Space	Can Kilic	2014-07-15	Scientific Series	View details
Cosmological Coincidence Problem		2014-07-15	Scientific Series	View details
Strong majorization entropic uncentainty relations	Karol Zyczkowski	2014-07-14	Scientific Series	View details
TBA		2014-07-08	Scientific Series	View details
Numerical investigations of singularities in general relativity	David Garfinkle	2014-06-26	Scientific Series	View details
On Quantum Tunnelling	Neil Turok	2014-06-25	Scientific Series	View details

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Physical Hilbert space for the affine group formulation of 4D, gravity of Lorentzian signature.

Asymmetric Hawking Radiation : Baryogenesis from Hawking Radiation

Space-Time Circuit-to-Hamiltonian construction and Its Applications

Supersymmetric AdS5 solutions in M-theory and Class S SCFT's

Inferring causal structure: a quantum advantage

Exploring N=1 theories of class S through Higgsing, dualizing and twisting

Improving Mass Measurements Using Many-Body Phase Space

Cosmological Coincidence Problem

Strong majorization entropic uncentainty relations

TBA

Numerical investigations of singularities in general relativity

On Quantum Tunnelling

Physical Hilbert space for the affine group formulation of 4D, gravity of Lorentzian signature.

Asymmetric Hawking Radiation : Baryogenesis from Hawking Radiation

Space-Time Circuit-to-Hamiltonian construction and Its Applications

Supersymmetric AdS5 solutions in M-theory and Class S SCFT's

Inferring causal structure: a quantum advantage

Exploring N=1 theories of class S through Higgsing, dualizing and twisting

Improving Mass Measurements Using Many-Body Phase Space

Cosmological Coincidence Problem

Strong majorization entropic uncentainty relations

TBA

Numerical investigations of singularities in general relativity

On Quantum Tunnelling