Scientific Series

Displaying 2953 - 2964 of 5014

How Quantum are the Cosmological Correlations?

Eugene Lim
King's College London
November 04, 2014

PIRSA:14110003
Cosmology
Experiments Big and Small

Savas Dimopoulos
Perimeter Institute for Theoretical Physics

October 31, 2014

PIRSA:14100116
Higgs Physics with the ATLAS experiment

Pierre Savard
University of Toronto
October 31, 2014

PIRSA:14100120
Particle Physics
Complex Loop Quantum Cosmology

Jibril Ben Achour
École Normale Supérieure de Lyon (ENS Lyon)
October 30, 2014

PIRSA:14100047
Quantum Gravity
Smooth Wilson loops from the continuum limit of null polygons

Jonathan Toledo
BMO Financial Group
October 30, 2014

PIRSA:14100118
Quantum Fields and Strings
Decoherence tests without quantum theory

Corsin Pfister
October 28, 2014

PIRSA:14100121
Quantum Foundations
Entanglement entropy of Wilson loops: Holography and matrix models

Simon Gentle
University of California, Los Angeles
October 28, 2014

PIRSA:14100006
Quantum Fields and Strings
Discovering the QCD Axion with Black Holes and Gravitational Waves

Masha Baryakhtar
University of Washington
October 28, 2014

PIRSA:14100049
Particle Physics
Beyond slow-roll - Daan Meerburg
October 28, 2014

PIRSA:14100119
Cosmology
Numerical Study of a Bosonic Topological Insulator in Three Dimensions

Scott Geraedts
California Institute of Technology
October 21, 2014

PIRSA:14100113
Condensed Matter
Disturbance in weak measurements and the difference between quantum and classical weak values

Asger Ipsen
October 21, 2014

PIRSA:14100114
Quantum Foundations
Three-Point Function in N=4 SYM and Spin Vertex

Yunfeng Jiang
October 21, 2014

PIRSA:14100079
Quantum Fields and Strings

How Quantum are the Cosmological Correlations?

Eugene Lim
King's College London
November 04, 2014

PIRSA:14110003
Cosmology
Experiments Big and Small

Savas Dimopoulos
Perimeter Institute for Theoretical Physics

October 31, 2014

PIRSA:14100116

I will talk about the implications of the current LHC results and the Higgs discovery on the principle of Naturalness, that has been guiding particle physics for the last forty years. Then I will discuss the role that low energy experiments can play for the future of particle physics.
Higgs Physics with the ATLAS experiment

Pierre Savard
University of Toronto
October 31, 2014

PIRSA:14100120
Particle Physics
An overview of the latest Higgs physics results from the ATLAS collaboration will be presented. Next year, the Large Hadron collider will restart at a higher collision energy after a 2-year shutdown. The Higgs physics programme for this next data taking period will be discussed.
Complex Loop Quantum Cosmology

Jibril Ben Achour
École Normale Supérieure de Lyon (ENS Lyon)
October 30, 2014

PIRSA:14100047
Quantum Gravity
We study in the context of loop quantum cosmology the effect of the analytic continuation that sends the Barbero-Immirzi parameter to a purely imaginary value. We show that this construction leads once again to a bouncing scenario, in which however the contracting and expanding phases on each side of the bounce are not symmetrical. Moreover, the minimal volume reached by the universe and the critical matter density become naturally independent of the Barbero-Immirzi parameter. This analytic continuation was first proposed in the context of black hole entropy calculation, and constitutes a proposal for defining a theory of self-dual quantum gravity in terms of the complex Ashtekar connection and for solving the so-called reality conditions. We expect that the systematic investigation of this analytic continuation in various setups will eventually lead to new insights on the status of the quantum states of complex Ashtekar gravity.
Smooth Wilson loops from the continuum limit of null polygons

Jonathan Toledo
BMO Financial Group
October 30, 2014

PIRSA:14100118
Quantum Fields and Strings
We present integral equations for the area of minimal surfaces in AdS_3 ending on generic smooth boundary contours. The equations are derived from the continuum limit of the AMSV result for null polygonal boundary contours. Remarkably these continuum equations admit exact solutions in some special cases. In particular we describe a novel exact solution which interpolates between the circle and 4-cusp solutions.
Decoherence tests without quantum theory

Corsin Pfister
October 28, 2014

PIRSA:14100121
Quantum Foundations
In quantum theory, people have thought for some while about the problem of how to estimate the decoherence of a quantum channel from classical data gained in measurements. Applications of these developments include security criteria for quantum key distribution and tests of decoherence models. In this talk, I will present some ideas for how to interpret the same classical data to make statements about decoherence in cases where nature is not necessarily described by quantum theory. This is work in progress in collaboration with many people.
Entanglement entropy of Wilson loops: Holography and matrix models

Simon Gentle
University of California, Los Angeles
October 28, 2014

PIRSA:14100006
Quantum Fields and Strings
A half-BPS circular Wilson loop in maximally supersymmetric SU(N) Yang-Mills theory in an arbitrary representation is described by a Gaussian matrix model with a particular insertion. The additional entanglement entropy of a spherical region in the presence of such a loop was recently computed by Lewkowycz and Maldacena using exact matrix model results. In this talk I will utilise the supergravity solutions that are dual to such Wilson loops in large representations to calculate this entropy holographically. Employing the results of Gomis, Matsuura, Okuda and Trancanelli to express this holographic entanglement entropy in a matrix model language, I will demonstrate complete agreement with the formula derived by Lewkowycz and Maldacena.
Discovering the QCD Axion with Black Holes and Gravitational Waves

Masha Baryakhtar
University of Washington
October 28, 2014

PIRSA:14100049
Particle Physics
In the next few years, Advanced LIGO will be the first experiment to detect gravitational waves. Through superradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with decay constant around or above the GUT scale. When an axion's Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole, forming a "gravitational atom". Due to superradiance, the number of axions occupying the bound levels grows exponentially, extracting energy and angular momentum from the black hole. I will discuss the promising gravitational wave signals from axions transitioning between levels of the gravitational atom and axions annihilating to gravitons. Events for axions in the range 10^−13 to 10^−10 eV can be visible at aLIGO. The signals produced are long-lasting, monochromatic, and can be distinguished from ordinary astrophysical sources. These signatures are also promising for lighter axions at future, lower-frequency, GW observatories. I will also present our updated exclusion on the QCD axion mass range of 6*10^−13 eV < ma < 1.5*10^−11 eV imposed by black hole spin measurements.
Beyond slow-roll - Daan Meerburg
October 28, 2014

PIRSA:14100119
Cosmology
We live in exciting times for cosmologists. There is a plethora of cosmological experiments that allow us to reconstruct the earliest moments in the Universe and test our ideas on how the Universe came into existence. Current data appear to favor an inflationary model that produces adiabatic, scale free, Gaussian fluctuations with an amplitude of 10^-5 in units of mK. WIthin the realm of cosmological models, it appears that such conditions are easily accomplished if we have a single light field slowly rolling down its potential. In this talk, I will investigate the possibility to what extend our current observations would allow for a deviation from slow-roll: several class of models predicts that the fluctuation spectra will contain superimposed features on top of their slow-roll solution. I will discuss these models and explain a novel way of extract these features from the data, both in the power spectrum as well as in the bispectrum. I will give the latest constraints from current cosmological surveys. In light of the possible detection of primordial gravitational waves, I will show that there exists evidence (3 sigma) that the data prefer a long wavelength feature driven by axion monodromy, a model that naturally predicts large tensor modes. From this I will derive a constraint on the axion decay constant. I will conclude with a discussion on how observations of higher order statistics and large scale structure could further constrain these models.
Numerical Study of a Bosonic Topological Insulator in Three Dimensions

Scott Geraedts
California Institute of Technology
October 21, 2014

PIRSA:14100113
Condensed Matter
We construct a model which realizes a (3+1)-dimensional symmetry-protected topological phase of bosons with U(1) charge conservation and time reversal symmetry, envisioned by A. Vishwanath and T. Senthil [PRX 4 011016]. Our model works by introducing an additional spin degree of freedom, and binding its hedgehogs to a species of charged bosons. We study the model using Monte Carlo and determine its bulk phase diagram; the phase where the bound states of hedgehogs and charges condense is the topological phase, and we demonstrate this by observing a Witten effect. We also study the surface phase diagram on a (2+1)-dimensional boundary between the topological and trivial insulators. We find a number of exotic phases on the surface, including exotic superfluids, a phase with a Hall conductivity quantized to half the value possible in 2D, and a phase with intrinsic topological order. We also find a new bulk phase with intrinsic topological order.
Disturbance in weak measurements and the difference between quantum and classical weak values

Asger Ipsen
October 21, 2014

PIRSA:14100114
Quantum Foundations
The role of measurement induced disturbance in weak measurements is of central importance for the interpretation of the weak value. Uncontrolled disturbance can interfere with the postselection process and make the weak value dependent on the details of the measurement process. Here we develop the concept of a generalized weak measurement for classical and quantum mechanics. The two cases appear remarkably similar, but we point out some important differences. A priori it is not clear what the correct notion of disturbance should be in the context of weak measurements. We consider three different notions and get three different results: (1) For a `strong' definition of disturbance, we find that weak measurements are disturbing. (2) For a weaker definition we find that a general class of weak measurements are non-disturbing, but that one gets weak values which depend on the measurement process. (3) Finally, with respect to an operational definition of the `degree of disturbance', we find that the AAV weak measurements are the least disturbing, but that the disturbance is still non-zero.
Three-Point Function in N=4 SYM and Spin Vertex

Yunfeng Jiang
October 21, 2014

PIRSA:14100079
Quantum Fields and Strings
In this talk I will explain how to compute three-point functions of N=4 SYM theory in the planar limit for tree level and one-loop in perturbation theory. First I will recall how to formulate the problem of computing the three-point function of operators with determined R-charges in the language of integrable spin chains. In the su(2) sector, the tree-level three point function can be obtained in terms of determinants, whose large R-charge limit can be taken explicitly. Then I will report a systematic method to compute the su(2) three point function at higher loops. In particular, we are able to take the semi-classical limit, and we can compare our result with the calculation from string theory. In the Frolov-Tseytlin limit we find a perfect match at one-loop. Finally I will present a new formalism of computing three-point functions called the spin vertex formalism, which is the weak coupling counter-part of the string vertex in the string field theory. I will describe how to construct the spin vertex and discuss its important properties.

Title	Speaker(s)	Date	Talk Type	Info link
How Quantum are the Cosmological Correlations?	Eugene Lim	2014-11-04	Scientific Series	View details
Experiments Big and Small	Savas Dimopoulos	2014-10-31	Scientific Series	View details
Higgs Physics with the ATLAS experiment	Pierre Savard	2014-10-31	Scientific Series	View details
Complex Loop Quantum Cosmology	Jibril Ben Achour	2014-10-30	Scientific Series	View details
Smooth Wilson loops from the continuum limit of null polygons	Jonathan Toledo	2014-10-30	Scientific Series	View details
Decoherence tests without quantum theory	Corsin Pfister	2014-10-28	Scientific Series	View details
Entanglement entropy of Wilson loops: Holography and matrix models	Simon Gentle	2014-10-28	Scientific Series	View details
Discovering the QCD Axion with Black Holes and Gravitational Waves	Masha Baryakhtar	2014-10-28	Scientific Series	View details
Beyond slow-roll - Daan Meerburg		2014-10-28	Scientific Series	View details
Numerical Study of a Bosonic Topological Insulator in Three Dimensions	Scott Geraedts	2014-10-21	Scientific Series	View details
Disturbance in weak measurements and the difference between quantum and classical weak values	Asger Ipsen	2014-10-21	Scientific Series	View details
Three-Point Function in N=4 SYM and Spin Vertex	Yunfeng Jiang	2014-10-21	Scientific Series	View details

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