This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.
A
quantum spin liquid is a solid whose atoms have magnetic moments but, because
of quantum fluctuations, these moments fluctuate like a liquid even at zero
temperature. Two dimensional spin liquids have been suggested as a way to
produce high temperature superconductivity, and to build quantum computers. Just as helium is the only element which is a liquid at zero temperature,
2D spin liquids have been extremely difficult to find, despite decades of
effort, raising the question, do realistic spin liquids even exist?
The recent discovery
of the Higgs boson is a fundamental advance in particle physics. This talk
gives a theorist's perspective of the significance of this discovery. The Higgs
boson was proposed in the 1960s, but it is best understood in the context of
the quest to understand the weak interactions, which began with Fermi's theory
of weak interactions almost 80 years ago. This has led to three very different
paradigms for the structure of fundamental interactions at the TeV scale:
This talk will begin by discussing one by one the various
reasons why cosmologists today consider the big bang inflationary cosmology to
be the leading, if not proven, theory of the universe and
then explaining
why each of these reasons is flawed. This leads
naturally to the question: what is the alternative? Understanding the flaws helps point the way.
Non-perturbative effects are responsible for the
essential dynamical features of the four-dimensional gauge theories such as
QCD. The N=2 supersymmetric four-dimensional theories are an interesting
class of models in which non-perturbative computations can be carried out with
arbitrary precision using localization of the path integrals. I will explain
the new exact non-perturbative results and the relation to classical and
quantum integrable systems for a large class of N=2 supersymmetric QCD.
As black holes accrete surrounding gas, they often
produce relativistic, collimated outflows, or jets. Jets are expected to form
in the black hole vicinity making them powerful probes of strong-field gravity.
However, how jet properties are connected to black hole and accretion flow
properties has been unclear. Recent progress in computer simulations of black
hole accretion enables studies of jet formation in unprecedented detail. For
the first time, 3D general relativistic magnetohydrodynamic numerical
Matrix
models, random maps and Liouville field
theory are prime tools which connect
random
geometry and quantum gravity in two dimensions. The
tensor track is a new program to extend this
connection to higher dimensions through
the
corresponding notions of tensor models, colored
triangulations and tensor group field theories.
In the last few years there has been a burst of
progress in the field of massive gravity. The construction of consistent
theories in which the graviton has a small mass has in turn led to the
development a new family of compelling, consistent low-energy modifications of
General Relativity. These theories improve our understanding of the
interplay between gravity and particle physics and provide new approaches to
solving the cosmological constant problem. In this talk I will review
While the luminosity and mass distributions of quasars
has evolved dramatically with cosmic time, the physical properties of quasars
of a given luminosity are remarkably independent of redshift. I will describe recent results on the spectra
of luminous quasars, the dark matter halos in which they sit, and the
intergalactic medium of their host galaxies, that are essentially
indistinguishable from moderate redshifts to z>6.
Advanced LIGO (aLIGO) and Advanced Virgo (AdV) are kilometer-scale
gravitational wave (GW) detectors that are expected to yield the first
direct observations of gravitational waves. I will describe the
currently projected schedule, sensitivity, and sky
localization accuracy for the GW detector network in the next decade.
I
will discuss some basic notions in the theory of phonology (sound systems
in language). The sounds of a language are generally assumed to be
composed of smaller constituents, called features. The features that
make up a sound cannot be directly obtained from its pronunciation, but
rather must be inferred from the system of contrasts that are at play
in a particular language. How to determine which features are contrastive
presents a logical and empirical puzzle that may be interesting