Scientific Series

Displaying 3133 - 3144 of 5085

TBA

Senthil Todadri Massachusetts Institute of Technology (MIT) - Department of Physics
August 19, 2014

PIRSA:14080036
Condensed Matter
Towards construction of a Wightman QFT in four dimensions

Raimar Wulkenhaar University of Münster

August 19, 2014

PIRSA:14080037
CMB anomalies from primordial gravitational waves

Yi Wang Hong Kong University of Science and Technology
August 13, 2014

PIRSA:14080019
Astrophysics
Reconstructing quantum states from local data

Isaac Kim University of California, Davis
August 12, 2014

PIRSA:14080007
Condensed Matter
Algebraic Geometry in Cosmology

Matilde Marcolli University of Toronto
August 07, 2014

PIRSA:14080002
Astrophysics
Criterion for non-Fermi Liquid behavior in a metal with broken symmetry

Ashvin Vishwanath Harvard University
August 06, 2014

PIRSA:14080004
Condensed Matter
Probing the Physics of Active Galaxies Using Multi-wavelength Data

Prajval Shastri Indian Institute of Astrophysics
August 05, 2014

PIRSA:14080000
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
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

TBA

Senthil Todadri Massachusetts Institute of Technology (MIT) - Department of Physics
August 19, 2014

PIRSA:14080036
Condensed Matter
Towards construction of a Wightman QFT in four dimensions

Raimar Wulkenhaar University of Münster

August 19, 2014

PIRSA:14080037

We prove that the $\lambda\phi^4_4$ quantum field theory on noncommutative Moyal space is, in the limit of infinite noncommutativity, exactly solvable in terms of the solution of a non-linear integral equation. The proof involves matrix model techniques which might be relevant for 2D quantum gravity and its generalisation to coloured tensor models of rank $\geq 3$. Surprisingly, our limit describes Schwinger functions of a Euclidean quantum field theory on standard $\mathbb{R}^4$ which satisfy the easy Osterwalder-Schrader axioms boundedness, covariance and symmetry. We prove that the decisive reflection positivity axiom is, for the 2-point function, equivalent to the question whether or not the solution of the integral equation is a Stieltjes function. The numerical solution of the integral equation leaves no doubt that this is true for coupling constants $\lambda\in[-0.39,0]$.
CMB anomalies from primordial gravitational waves

Yi Wang Hong Kong University of Science and Technology
August 13, 2014

PIRSA:14080019
Astrophysics
We relate CMB anomalies and the recent observational evidence of primordial gravitational
waves. Two aspects are investigated:

(a) Several anomalies are spotted on the low ell temperature map of the WMAP and Planck
experiments. However, those anomalies disappear at high ell. We propose that those low ell
temperature anomalies may come from nearly scale invariant anomalies of the tensor sector.
Those anomalies on the temperature map naturally decay towards small scales, characterized
by the tensor-to-temperature radiation transfer function.

(b) The anomalies introduced by the gravitational waves discovery. Strong tension is noticed
between the BICEP2 and Planck data. We study in detail how blue tilt of the tensor spectrum
reconciles the tension between those datasets.
Reconstructing quantum states from local data

Isaac Kim University of California, Davis
August 12, 2014

PIRSA:14080007
Condensed Matter
We consider the problem of reconstructing global quantum states from local data. Because the reconstruction problem has many solutions in general, we consider the reconstructed state of maximum global entropy consistent with the local data. We show that unique ground states of local Hamiltonians are exactly reconstructed as the maximal entropy state. More generally, we show that if the state in question is a ground state of a local Hamiltonian with a degenerate space of locally indistinguishable ground states, then the maximal entropy state is close to the ground state projector. We also show that local reconstruction is possible for thermal states of local Hamiltonians. Finally, we discuss a procedure to certify that the reconstructed state is close to the true global state. We call the entropy of our reconstructed maximum entropy state the "reconstruction entropy", and we discuss its relation to emergent geometry in the context of holographic duality. This is a joint work with Brian Swingle.
Algebraic Geometry in Cosmology

Matilde Marcolli University of Toronto
August 07, 2014

PIRSA:14080002
Astrophysics
The talk is based on joint work with Yuri Manin (arXiv:1402.2158). Using algebro-geometric blowups it is possible to construct a family of models of gluing of aeons across a Big-Bang type singularity, which includes the case of Penrose's conformally cyclic cosmology, as well as inflationary multiverse models generalizing the "eternal symmetree", and BKLL mixmaster type cosmologies. Using the mixmaster dynamics, formulated in terms of elliptic curves and modular curves, we speculate on the geometry of cosmological time near the gluing of aeons. We show also that this type of model allows for phenomena of noncommutativity of spacetime coordinates near the Big-Bang and the crossing of aeons.
Criterion for non-Fermi Liquid behavior in a metal with broken symmetry

Ashvin Vishwanath Harvard University
August 06, 2014

PIRSA:14080004
Condensed Matter
Probing the Physics of Active Galaxies Using Multi-wavelength Data

Prajval Shastri Indian Institute of Astrophysics
August 05, 2014

PIRSA:14080000
Astrophysics
Accreting supermassive black holes in the centres of galaxies (i.e. Active Galactic Nuclei - AGN) are now known to play a prominent role in the growth of galaxies through cosmic time. The fundamental parameters to explain the whole range of observed properties of these accreting systems, however, is still elusive. We will present some results from multi-wavelength investigations of the nature of accreting supermassive black holes, including those that produce low kinetic power jets as well as high kinetic power, relativistic jets.
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

Title	Speaker(s)	Date	Talk Type	Info link
TBA	Senthil Todadri	2014-08-19	Scientific Series	View details
Towards construction of a Wightman QFT in four dimensions	Raimar Wulkenhaar	2014-08-19	Scientific Series	View details
CMB anomalies from primordial gravitational waves	Yi Wang	2014-08-13	Scientific Series	View details
Reconstructing quantum states from local data	Isaac Kim	2014-08-12	Scientific Series	View details
Algebraic Geometry in Cosmology	Matilde Marcolli	2014-08-07	Scientific Series	View details
Criterion for non-Fermi Liquid behavior in a metal with broken symmetry	Ashvin Vishwanath	2014-08-06	Scientific Series	View details
Probing the Physics of Active Galaxies Using Multi-wavelength Data	Prajval Shastri	2014-08-05	Scientific Series	View details
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

Supported by

Format results

TBA

Towards construction of a Wightman QFT in four dimensions

CMB anomalies from primordial gravitational waves

Reconstructing quantum states from local data

Algebraic Geometry in Cosmology

Criterion for non-Fermi Liquid behavior in a metal with broken symmetry

Probing the Physics of Active Galaxies Using Multi-wavelength Data

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

TBA

Towards construction of a Wightman QFT in four dimensions

CMB anomalies from primordial gravitational waves

Reconstructing quantum states from local data

Algebraic Geometry in Cosmology

Criterion for non-Fermi Liquid behavior in a metal with broken symmetry

Probing the Physics of Active Galaxies Using Multi-wavelength Data

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