Talks

8953 - 8964 of 16769 Results

PHYS 781 - Lecture 13

Niayesh Afshordi University of Waterloo

October 31, 2014

PIRSA:14100065
Complex Loop Quantum Cosmology

Jibril Ben Achour Ludwig-Maximilians-Universität München (LMU)

October 30, 2014

PIRSA:14100047

Quantum Gravity
PHYS 781 - Lecture 12

Niayesh Afshordi University of Waterloo

October 30, 2014

PIRSA:14100060
Smooth Wilson loops from the continuum limit of null polygons

Jonathan Toledo BMO Financial Group

October 30, 2014

PIRSA:14100118

Quantum Fields and Strings
Entanglement Entropy and the Area Law - Lecture 4

Rafael Sorkin Perimeter Institute for Theoretical Physics

October 28, 2014

PIRSA:14100072
Decoherence tests without quantum theory

Corsin Pfister

October 28, 2014

PIRSA:14100121

Quantum Foundations
PHYS 781 - Lecture 11

Niayesh Afshordi University of Waterloo

October 28, 2014

PIRSA:14100055
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
14/15 PSI - Conformal Field Theory - Lecture 14

Freddy Cachazo Perimeter Institute for Theoretical Physics

October 24, 2014

PIRSA:14100026
PHYS 781 - Lecture 10

Niayesh Afshordi University of Waterloo

October 24, 2014

PIRSA:14100064

PHYS 781 - Lecture 13

Niayesh Afshordi University of Waterloo

October 31, 2014

PIRSA:14100065
Complex Loop Quantum Cosmology

Jibril Ben Achour Ludwig-Maximilians-Universität München (LMU)

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.
PHYS 781 - Lecture 12

Niayesh Afshordi University of Waterloo

October 30, 2014

PIRSA:14100060
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.
Entanglement Entropy and the Area Law - Lecture 4

Rafael Sorkin Perimeter Institute for Theoretical Physics

October 28, 2014

PIRSA:14100072
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.
PHYS 781 - Lecture 11

Niayesh Afshordi University of Waterloo

October 28, 2014

PIRSA:14100055
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.
14/15 PSI - Conformal Field Theory - Lecture 14

Freddy Cachazo Perimeter Institute for Theoretical Physics

October 24, 2014

PIRSA:14100026
PHYS 781 - Lecture 10

Niayesh Afshordi University of Waterloo

October 24, 2014

PIRSA:14100064

Title	Date	Collection	Type	Info
PHYS 781 - Lecture 13	2014‑10‑31	PHYS 781 - Fundamentals of Astrophysics	Course	View details
Complex Loop Quantum Cosmology	2014‑10‑30	Quantum Gravity	Scientific Series	View details
PHYS 781 - Lecture 12	2014‑10‑30	PHYS 781 - Fundamentals of Astrophysics	Course	View details
Smooth Wilson loops from the continuum limit of null polygons	2014‑10‑30	Quantum Fields and Strings	Scientific Series	View details
Entanglement Entropy and the Area Law - Lecture 4	2014‑10‑28	Entanglement Entropy and the Area Law	Course	View details
Decoherence tests without quantum theory	2014‑10‑28	Quantum Foundations	Scientific Series	View details
PHYS 781 - Lecture 11	2014‑10‑28	PHYS 781 - Fundamentals of Astrophysics	Course	View details
Entanglement entropy of Wilson loops: Holography and matrix models	2014‑10‑28	Quantum Fields and Strings	Scientific Series	View details
Discovering the QCD Axion with Black Holes and Gravitational Waves	2014‑10‑28	Particle Physics	Scientific Series	View details
Beyond slow-roll - Daan Meerburg	2014‑10‑28	Cosmology and Gravitation	Scientific Series	View details
14/15 PSI - Conformal Field Theory - Lecture 14	2014‑10‑24	14/15 PSI - Conformal Field Theory	Course	View details
PHYS 781 - Lecture 10	2014‑10‑24	PHYS 781 - Fundamentals of Astrophysics	Course	View details

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