Scientific Series

Displaying 3073 - 3084 of 5012

Physics, Logic and Mathematics of Time

Louis Kauffman
University of Illinois at Chicago
May 02, 2014

PIRSA:14050032
Quantum Foundations
Group Field Theory in dimension 4 - ε

Sylvain Carrozza
University of Burgundy
May 01, 2014

PIRSA:14050001
Quantum Gravity
Geometric inequalities for black holes

Sergio Dain
Universidad Nacional de Cordoba
May 01, 2014

PIRSA:14050030
Strong Gravity
Quantum thermalization and many-body Anderson localization

David Huse
Princeton University
April 30, 2014

PIRSA:14040066
Quantum Foundations
Probing renormalization group flows using entanglement entropy

Mark Mezei
Massachusetts Institute of Technology (MIT)
April 30, 2014

PIRSA:14040144
Quantum Fields and Strings
Helical edge resistance introduced by charge disorder

Leonid Glazman
Yale University
April 29, 2014

PIRSA:14040082
Condensed Matter
Localizing Braneworlds in Infinite Spaces

Kellogg Stelle
Imperial College London
April 29, 2014

PIRSA:14040064
Quantum Fields and Strings
Galileon Maps: Inequivalent Coset Constructions for Spacetime Symmetries

Gabirele Trevisan
SISSA International School for Advanced Studies
April 29, 2014

PIRSA:14040132
Cosmology
3d N = 4 Gauge Theories, Mirror Symmetry and Hilbert series

Noppadol Mekareeya
Imperial College London
April 28, 2014

PIRSA:14040143
Quantum Fields and Strings
TBA

Eun-Gook Moon
Korea Advanced Institute of Science and Technology (KAIST)

April 25, 2014

PIRSA:14040142
The characteristic structure of the Weyl curvature tensor and its utilization

Fan Zhang
Beijing Normal University
April 24, 2014

PIRSA:14040139
Strong Gravity
Conformal Standard Model

Krzysztof Meissner
University of Warsaw

April 23, 2014

PIRSA:14040061

Physics, Logic and Mathematics of Time

Louis Kauffman
University of Illinois at Chicago
May 02, 2014

PIRSA:14050032
Quantum Foundations
Consider discrete physics with a minimal time step taken to be
tau. A time series of positions q,q',q'', ... has two classical
observables: position (q) and velocity (q'-q)/tau. They do not commute,
for observing position does not force the clock to tick, but observing
velocity does force the clock to tick. Thus if VQ denotes first observe
position, then observe velocity and QV denotes first observe velocity,
then observe position, we have
VQ: (q'-q)q/tau
QV: q'(q'-q)/tau
(since after one tick the position has moved from q to q').
Thus [Q,V]= QV - VQ = (q'-q)^2/tau. If we consider the equation
[Q,V] = k (a constant), then k = (q'-q))^2/tau and this is recognizably
the diffusion constant that arises in a process of Brownian motion.
Thus, starting with the simplest assumptions for discrete physics, we are
lead to recognizable physics. We take this point of view and follow it
in both physical and mathematical directions. A first mathematical
direction is to see how i, the square root of negative unity, is related
to the simplest time series: ..., -1,+1,-1,+1,... and making the
above analysis of time series more algebraic leads to the following
interpetation for i. Let e=[-1,+1] and e'=[+1,-1] denote, as ordered
pairs, two phase-shifted versions of the alternating series above.
Define an operator b such that eb = be' and b^2 = 1. Regard b as a time
shifting operator. The operator b shifts the alternating series by one
half its period. Regard e' = -e and ee' = [-1.-1] = -1 (combining term by
term). Then let i = eb. We have ii = (eb)(eb) = ebeb = ee'bb = -1. Thus ii = -1
through the definition of i as eb, a temporally sensitive entity that
shifts it phase in the course of interacting with (a copy of) itself.
By going to i as a discrete dynamical system, we can come back to the
general features of discrete dynamical systems and look in a new way at
the role of i in quantum mechanics. Note that the i we have constructed is
already part of a simple Clifford algebra generated by e and b with
ee = bb = 1 and eb + be = 0. We will discuss other mathematical physical
structures such as the Schrodinger equation, the Dirac equation and the
relationship of a simple logical operator (generalizing negation) with
Majorana Fermions.
Group Field Theory in dimension 4 - ε

Sylvain Carrozza
University of Burgundy
May 01, 2014

PIRSA:14050001
Quantum Gravity
Rank 3 tensorial group fields theories with gauge invariance condition appear to be renormalizable on dimension 3 groups such as SU(2), but also on dimension 4 groups. Building on an analogy with ordinary scalar field theories, I will generalize such models to group dimension 4 - ε, and discuss what this might teach us about the physically relevant SU(2) case.
Geometric inequalities for black holes

Sergio Dain
Universidad Nacional de Cordoba
May 01, 2014

PIRSA:14050030
Strong Gravity
A geometric inequality in General Relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole (angular momentum, charge, mass and horizon area) satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities, which are valid in the dynamical and strong field regime, play an important role in the characterization of the gravitational collapse. They are closed related with the cosmic censorship conjecture. Also, variants of these inequalities are valid for ordinary bodies. In this talk I will review recent results in this subject.
Quantum thermalization and many-body Anderson localization

David Huse
Princeton University
April 30, 2014

PIRSA:14040066
Quantum Foundations
Progress in physics and quantum information science motivates much recent study of the behavior of strongly-interacting many-body quantum systems fully isolated from their environment, and thus undergoing unitary time evolution. What does it mean for such a system to go to thermal equilibrium? I will explain the Eigenstate Thermalization Hypothesis (ETH), which posits that each individual exact eigenstate of the system's Hamiltonian is at thermal equilibrium, and which appears to be true for most (but not all) quantum many-body systems. Prominent among the systems that do not obey this hypothesis are quantum systems that are many-body Anderson localized and thus do not constitute a reservoir that can thermalize itself. When the ETH is true, one can do standard statistical mechanics using the `single-eigenstate ensembles', which are the limit of the microcanonical ensemble where the `energy window' contains only a single many-body quantum state. These eigenstate ensembles are more powerful than the traditional statistical mechanical ensembles, in that they can also "see" the quantum phase transition in to the localized phase, as well as a rich new world of phases and phase transitions within the localized phase.
Probing renormalization group flows using entanglement entropy

Mark Mezei
Massachusetts Institute of Technology (MIT)
April 30, 2014

PIRSA:14040144
Quantum Fields and Strings
The entanglement entropy of the vacuum of a quantum field theory contains information about physics at all scales and is UV sensitive. A simple refinement of entanglement entropy gets rid of its UV divergence, and allows us to extract entanglement per scale. In two and three spacetime dimensions this quantity can be used as a proxy for the number of degrees of freedom, as it decreases under RG flow. We investigate its behavior around fixed points, and reveal its interesting analytic structure in the space of couplings.
Helical edge resistance introduced by charge disorder

Leonid Glazman
Yale University
April 29, 2014

PIRSA:14040082
Condensed Matter
Electron puddles created by doping of a 2D topological insulator may violate the ideal helical edge conductance. Because of a long electron dwelling time, even a single puddle may lead to a significant inelastic backscattering. We find the resulting correction to the perfect edge conductance. Generalizing to multiple puddles, we assess the dependence of the helical edge resistance on temperature and on the doping level. Puddles with odd electron number carry a spin and lead to a logarithmically-weak temperature dependence of the resistivity of a long edge. The developed theory provides a framework for analyzing the results of the past and ongoing electron transport experiments with 2D topological insulators
Localizing Braneworlds in Infinite Spaces

Kellogg Stelle
Imperial College London
April 29, 2014

PIRSA:14040064
Quantum Fields and Strings
There have been a number of attempts to achieve a localization of gravity on a braneworld hypersurface embedded in an infinite spacetime, but these have all fallen short of what might be desired, for various reasons. There have even been no-go theorems claimed for constructions made using just accepted elements of string or M theory. The talk will present a proposed resolution of this problem based upon a hyperbolic solution of type IIA theory with a superposed NS-5 brane. Gravity is bound to the brane surface owing to the existence of a single normalizable bound state of the transverse space Laplacian.
Galileon Maps: Inequivalent Coset Constructions for Spacetime Symmetries

Gabirele Trevisan
SISSA International School for Advanced Studies
April 29, 2014

PIRSA:14040132
Cosmology
Non-linear realizations of spacetime symmetries can be obtained by a generalization of the coset construction valid for internal ones. The physical equivalence of different representations for spacetime symmetries is not obvious, since their relation involves not only a redefinition of the fields but also a field-dependent change of coordinates. A simple and relevant spacetime symmetry is obtained by the contraction of the 4D conformal group that leads to the Galileon group. In this talk I will analyze two non-linear realizations of this group, focusing in particular on the propagation of signals around non-trivial backgrounds.
3d N = 4 Gauge Theories, Mirror Symmetry and Hilbert series

Noppadol Mekareeya
Imperial College London
April 28, 2014

PIRSA:14040143
Quantum Fields and Strings
This talk focuses on vacuum moduli spaces of N=4 supersymmetric field theories in three dimensions. A particular branch of the moduli space, known as the Coulomb branch, receives quantum corrections. We present an exact result, known as the Hilbert series, that enumerates the operators in the chiral ring of such a quantum Coulomb branch. This exact result can be applied to a large class of 3d supersymmetric field theories, with and without known Lagrangian descriptions. As an application, we present a method to compute partition functions of instantons on C^2 for any simple group, including exceptional and non-simply-laced ones.
TBA

Eun-Gook Moon
Korea Advanced Institute of Science and Technology (KAIST)

April 25, 2014

PIRSA:14040142
The characteristic structure of the Weyl curvature tensor and its utilization

Fan Zhang
Beijing Normal University
April 24, 2014

PIRSA:14040139
Strong Gravity
The talk will summarize some results relating to clarifying the physical significance of the characteristic structure of the Weyl curvature tensor, and proposals for its utilization. I will begin by showing how null force-free or vacuum electrodynamic solutions experience reduced scattering by propagating along the principal null directions (GPNDs) of the spacetime, as if they were the flatter directions of the curvature tensor. Building on this observation, I will use complexified sectional curvatures to develop an analogy between the Weyl tensor and the second fundamental form of an immersed surface, and argue that, despite their name, the GPNDs are more akin to the asymptotic directions rather than the principal directions. I will also identify the ``true'' principal directions and curvatures, which has so far been under-utilized. I will then move on to propose usage for these quantities in topics related to the peeling theorem, the large scale geometry of the spacetime, the transition from the merger phase of binary black hole merger into the quasinormal mode ringdown phase, and perturbation of generic background spacetimes.
Conformal Standard Model

Krzysztof Meissner
University of Warsaw

April 23, 2014

PIRSA:14040061

I will describe a proposal of an enlargement of the Standard Model based on a softly broken conformal symmetry. It contains the usual particles of the SM with right-chiral neutrinos and predicts two new particles: a scalar mixing with the usual Higgs and a naturally weakly coupled axion. I will argue that the Planck scale should be treated as a real physical scale and discuss the hierarchy problem and renormalization from this point of view. I will show that the model does not need any intermediate scales and can be viable up to the Planck scale (in distiction to the Standard Model). I will present experimental predictions of the model.

Title	Speaker(s)	Date	Talk Type	Info link
Physics, Logic and Mathematics of Time	Louis Kauffman	2014-05-02	Scientific Series	View details
Group Field Theory in dimension 4 - ε	Sylvain Carrozza	2014-05-01	Scientific Series	View details
Geometric inequalities for black holes	Sergio Dain	2014-05-01	Scientific Series	View details
Quantum thermalization and many-body Anderson localization	David Huse	2014-04-30	Scientific Series	View details
Probing renormalization group flows using entanglement entropy	Mark Mezei	2014-04-30	Scientific Series	View details
Helical edge resistance introduced by charge disorder	Leonid Glazman	2014-04-29	Scientific Series	View details
Localizing Braneworlds in Infinite Spaces	Kellogg Stelle	2014-04-29	Scientific Series	View details
Galileon Maps: Inequivalent Coset Constructions for Spacetime Symmetries	Gabirele Trevisan	2014-04-29	Scientific Series	View details
3d N = 4 Gauge Theories, Mirror Symmetry and Hilbert series	Noppadol Mekareeya	2014-04-28	Scientific Series	View details
TBA	Eun-Gook Moon	2014-04-25	Scientific Series	View details
The characteristic structure of the Weyl curvature tensor and its utilization	Fan Zhang	2014-04-24	Scientific Series	View details
Conformal Standard Model	Krzysztof Meissner	2014-04-23	Scientific Series	View details

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