Scientific Series

Displaying 3241 - 3252 of 5012

Aspects of Modified Gravity

Jeremy Sakstein
University of Pennsylvania
October 31, 2013

PIRSA:13100132
Cosmology
Asymptotically Optimal Topological Quantum Compiling

Vadym Kliuchnikov
University of Waterloo
October 30, 2013

PIRSA:13100129
Quantum Information
Gravity and the Search for New Physics with Cosmology

Kris Sigurdson
University of British Columbia
October 30, 2013

PIRSA:13100098
Particle Physics
Silicene - a Wonder Electron Carpet

Baskaran Ganapathy
Institute of Mathematical Sciences
October 29, 2013

PIRSA:13100128
Condensed Matter
The Geometry of Supersymmetric Partition Functions

Guido Festuccia
Institute for Advanced Study (IAS) - School of Mathematics
October 29, 2013

PIRSA:13100130
Quantum Fields and Strings
Minimal Distances and the RG Flow
October 29, 2013

PIRSA:13100069
Particle Physics
Mapping Mass Across The Sky: CMB Lensing Measurements Past and Future

Blake Sherwin
Princeton University
October 29, 2013

PIRSA:13100075
Cosmology
Asymptotically safe matrix models

Tim Koslowski
Technical University of Applied Sciences Würzburg-Schweinfurt
October 24, 2013

PIRSA:13100067
Quantum Gravity
The Stokes groupoids

Marco Gualtieri
University of Toronto

October 23, 2013

PIRSA:13100110
Wilsonian and large N approaches to non-Fermi liquids

Shamit Kachru
Stanford University
October 22, 2013

PIRSA:13100109
Condensed Matter
Conformal symmetry and cosmology

Austin Joyce
University of Chicago
October 22, 2013

PIRSA:13100070
Cosmology
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle

Richard Hill
University of Kentucky
October 18, 2013

PIRSA:13100107
Particle Physics

Aspects of Modified Gravity

Jeremy Sakstein
University of Pennsylvania
October 31, 2013

PIRSA:13100132
Cosmology
In this talk I will give an introduction to some of my research into modified gravity over the last three years. I will begin by describing my implementation of chameleon models into supersymmetry and discuss some of the new features and cosmology that arise in this formalism. I will then change direction and talk about my work using astrophysical effects as novel probes of modified gravity theories and present some new results on modified gravity stellar oscillation theory. I will end by discussing work in progress and the possible future constraints that could be placed.
Asymptotically Optimal Topological Quantum Compiling

Vadym Kliuchnikov
University of Waterloo
October 30, 2013

PIRSA:13100129
Quantum Information
In a topological quantum computer, universality is achieved by braiding and quantum information is natively protected from small local errors. We address the problem of compiling single-qubit quantum operations into braid representations for non-abelian quasiparticles described by the Fibonacci anyon model. We develop a probabilistically polynomial algorithm that outputs a braid pattern to approximate a given single-qubit unitary to a desired precision. We also classify the single-qubit unitaries that can be implemented exactly by a Fibonacci anyon braid pattern and present an efficient algorithm to produce their braid patterns. Our techniques produce braid patterns that meet the uniform asymptotic lower bound on the compiled circuit depth and thus are depth-optimal asymptotically. Our compiled circuits are significantly shorter than those output by prior state-of-the-art methods, resulting in improvements in depth by factors ranging from 20 to 1000 for precisions ranging between 10^{−10} and 10^{−30}.
Gravity and the Search for New Physics with Cosmology

Kris Sigurdson
University of British Columbia
October 30, 2013

PIRSA:13100098
Particle Physics
Despite its feeble in strength, gravity plays a pivotal role in shaping our Universe and the things in it. Ever since Newton formulated his universal law of gravitation the recognition that all things gravitate has been nearly sacrosanct. Repeatedly, apparent gravitational anomalies have either foretold the existence of new physics or a misunderstanding of gravity itself, from the existence of nuclear forces to Einstein's general relativity. Eighty years ago gravity betrayed the existence of dark matter, and fifteen years ago gravity demanded dark energy from reluctant cosmologists. I will discuss how gravity enables modern cosmology to explore the echoes of the invisible universe, even if it is impossible or difficult to directly see the invisible universe. In particular, I will show how gravity enables us to put surprisingly severe constraints on the coupling of dark matter to new light particles and search for secret interactions between Fermi's elusive neutrinos. The physics and cosmic history of the invisible universe are writ large across the cosmos itself, and gravity is our tried and trusted messenger.
Silicene - a Wonder Electron Carpet

Baskaran Ganapathy
Institute of Mathematical Sciences
October 29, 2013

PIRSA:13100128
Condensed Matter
Graphene is a 2 dimensional net of strongly bonded carbon atoms. This magic carpet has taken us to new heights in the last decade. Silicene and Germanene are analogue nets, made of silicon and germanium atoms respectively, but with a relatively weaker chemical bond. I will argue that these carpets perform some new tricks by not being a carbon copy of graphene. We have suggested [1] that silicene and germanene are Mott insulators and potential abode for room temperature superconductivity, quantum spin liquids and more
The Geometry of Supersymmetric Partition Functions

Guido Festuccia
Institute for Advanced Study (IAS) - School of Mathematics
October 29, 2013

PIRSA:13100130
Quantum Fields and Strings
Three-dimensional N=2 theories with a U(1)_R symmetry, can be placed on a compact three manifold M preserving some supersymmetry if and only if M admits a transversely holomorphic foliation (THF). I will show that the partition function of the resulting theory is independent of the metric and depends holomorphically on the moduli of the THF. When applied to supersymmetric field theories on manifolds diffeomorphic to S^3 and S^2 x S^1, this result explains many of the properties observed in explicit determinations of their partition functions.
Minimal Distances and the RG Flow
October 29, 2013

PIRSA:13100069
Particle Physics
We will discuss the renormalization group flow between different classes of CFTs in four dimensions and study possible lower bounds on the "distances" between these theories.
Mapping Mass Across The Sky: CMB Lensing Measurements Past and Future

Blake Sherwin
Princeton University
October 29, 2013

PIRSA:13100075
Cosmology
Measurements of gravitational lensing in the Cosmic Microwave Background (CMB) directly probe the projected distribution of dark matter out to high redshifts. The CMB lensing maps thus encode a wealth of information about both fundamental physics (e.g., dark energy and neutrino properties) and high-redshift astrophysics. I will illustrate this by first reviewing measurements of CMB lensing with the Atacama Cosmology Telescope, discussing both CMB lensing auto-correlations and cross-correlations with quasars, galaxies and optical lensing. I will then discuss ongoing and upcoming measurements of CMB polarization lensing with the POLARBEAR and ACTPol experiments and explain the great scientific potential of such polarization lensing studies in the very near future.
Asymptotically safe matrix models

Tim Koslowski
Technical University of Applied Sciences Würzburg-Schweinfurt
October 24, 2013

PIRSA:13100067
Quantum Gravity
The functional renormalization group is a tool in the systematic search for Euclidean QFTs that works with very little input: All one needs to specify is a field content, symmetries and a notion of locality. The functional renormalization group then allows one to scan this theory space for bare actions for which the path integral can be performed nonperturbatively. These actions appear as fixed points (and relevant deformations) of the renormalization group flow (so-called asymptotic safety). Such a systematic search has so far not been performed for the tensor model approach to quantum gravity. We investigate matrix models for 2-dimensional gravity and the Grosse-Wulkenhaar model, which is a simple tensor model for a 4D noncommutative scalar field theory, as a first step. I will report on work, done in collaboration with Astrid Eichhorn and Alessandro Sfondrini, where we confirmed asymptotic safety purely through functional RG methods. Based on the lessons learned from these models I will summarize how the usual continuum RG approach has to be generalized for the investigation of tensor models and conclude with a recipe for the investigation of general tensor models.
The Stokes groupoids

Marco Gualtieri
University of Toronto

October 23, 2013

PIRSA:13100110

Ordinary differential equations become much less ordinary when they are allowed to have singularities. Solving them naively in formal power series, one often obtains divergent series, just as in the perturbation series for physical observables in quantum field theory. The asymptotic interpretation of this divergent series exhibits the famous Stokes phenomenon, an essential ingredient in any full description of the solutions to the system. I will explain a new viewpoint on singular ODE which illuminates the geometric meaning of the phenomena described above, and which can be applied to the problem of resummation of formal power series. This viewpoint uses a very basic but underused tool in differential geometry: Lie groupoids. A Lie groupoid is as natural and essential an object as a Lie group; I shall explain how to build examples of them and how to use them to solve singular differential equations.
Wilsonian and large N approaches to non-Fermi liquids

Shamit Kachru
Stanford University
October 22, 2013

PIRSA:13100109
Condensed Matter
We use Wilsonian RG and large N techniques to study the quantum field theory of a critical boson interacting with a Fermi surface, and compare/contrast the results with those coming from holography.
Conformal symmetry and cosmology

Austin Joyce
University of Chicago
October 22, 2013

PIRSA:13100070
Cosmology
We will explore the role that conformal symmetries may play in cosmology. First, we will discuss the symmetries underlying the statistics of the primordial perturbations which seeded the temperature anisotropies of the Cosmic Microwave Background. I will show how symmetry considerations lead us to three broad classes of theories to explain these perturbations: single-field inflation, multi-field inflation, and the conformal mechanism. We will discuss the symmetries in each case and derive their model-independent consequences. Finally, we will examine the possibility of violating the null energy condition with a well-behaved quantum field theory.
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle

Richard Hill
University of Kentucky
October 18, 2013

PIRSA:13100107
Particle Physics
Heavy particle expansions, familiar from heavy quark physics, have found important applications in the analysis of dark matter candidates and their interactions with the Standard Model. From a different direction, precision spectroscopy of muonic hydrogen has challenged QED and required more precise knowledge of proton structure. These problems have forced a closer examination of the construction of general heavy particle lagrangians at high orders in the 1/M expansion, and in the absence of known ultraviolet completions. Key aspects of this formalism, including the emergence of Lorentz invariance from "nonrelativistic" lagrangians, are reviewed, and several applications are presented. A status report on the proton radius puzzle is given.

Title	Speaker(s)	Date	Talk Type	Info link
Aspects of Modified Gravity	Jeremy Sakstein	2013-10-31	Scientific Series	View details
Asymptotically Optimal Topological Quantum Compiling	Vadym Kliuchnikov	2013-10-30	Scientific Series	View details
Gravity and the Search for New Physics with Cosmology	Kris Sigurdson	2013-10-30	Scientific Series	View details
Silicene - a Wonder Electron Carpet	Baskaran Ganapathy	2013-10-29	Scientific Series	View details
The Geometry of Supersymmetric Partition Functions	Guido Festuccia	2013-10-29	Scientific Series	View details
Minimal Distances and the RG Flow		2013-10-29	Scientific Series	View details
Mapping Mass Across The Sky: CMB Lensing Measurements Past and Future	Blake Sherwin	2013-10-29	Scientific Series	View details
Asymptotically safe matrix models	Tim Koslowski	2013-10-24	Scientific Series	View details
The Stokes groupoids	Marco Gualtieri	2013-10-23	Scientific Series	View details
Wilsonian and large N approaches to non-Fermi liquids	Shamit Kachru	2013-10-22	Scientific Series	View details
Conformal symmetry and cosmology	Austin Joyce	2013-10-22	Scientific Series	View details
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle	Richard Hill	2013-10-18	Scientific Series	View details

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