642 Works

Modular invariance and holographic CFTs

Modular invariance plays an important role in AdS3/CFT2 holography. I discuss the structure of non-holomorphic CFT partition functions, namely in what sense the light spectrum determines the heavy spectrum and how to construct example partition functions using Poincare series. This yields necessary conditions on the spectrum of holographic CFTs. Finally I will discuss permutation orbifolds as examples of such theories.

Discussion 2

How much information is there in large scale structure?

Large scale structure contains vastly more Fourier modes than the CMB, and is therefore a promising arena for studying the early universe.  One obstacle to using these modes is the non-linearity of structure formation. The amount of weakly coupled information available is therefore very sensitive to scale at which non-linear effects become important and simulations become necessary.  Using effective field theory techniques, I will present evidence that the perturbative description of dark matter is much...

Evolving Laws: Chapter 8 - Kalypso Nicolaidis opening statement

How should one create a dialogue between the natural and social sciences?;
Social theory already presents a scenario of evolving laws;
Meta-laws in social theory;

Impact cratering and the evolution of planetary surfaces in the solar system – The Chicxulub impact

Impacts of asteroid and comets constitute major geologic processes shaping the surfaces and evolution of planetary bodies. Impacts produce deep transient cavities, with excavation to deep crustal levels, fragmentation, and removal of large rock volumes. Formation of complex craters involves high pressures and temperatures resulting in intense deformation, fracturing and melting. Here, we analyze the crater-forming impacts and their effects on the Earth´s climate, environment and life-support systems, in relation to the Cretaceous/Paleogene (K/Pg) boundary....

Quantum Materials Discovery: The Synthesis of Geometrically Frustrated Magnets

In the last few decades, there has been a marked rise in the diversity of compounds studied with frustrated networks of spins. This was clearly not the case in the early days of this field, where only a handful of “model” systems were being studied (ie. in two dimensions, the triangular or kagome lattices, and in three dimensions, the pyrochlore lattice).  Solid state chemists have played a major role in not only the identification of new geometrically...

Fractionalized Topological Insulators in Frustrated Magnets

Spin liquid phases in frustrated magnets may arise in a variety of forms. Here we discuss the possibility of topological insulators of spinons or the fractionalized excitations in spin liquids. These phases should be characterized by "both" of the two popular and different definitions of topological orders, namely the long-range entanglement and the symmetry-protected topological order. We show an explicit construction of such a state in frustrated magnets on the pyrochlore lattice and discuss novel...

Far Infrared Study of Magnetic Field Induced Normal States of La1.94Sr0.06CuO4

We report on the ab-plane optical properties of the magnetic field inducednormal state of underdoped La1.94Sr0.06CuO4  (Tc=5.5 K), the first such study. We apply strong magnetic fields (4 T and 16 T) along the c-axis. We find that a 4 T field is strong enough to destroy the superconducting condensate.  However at higher fields we observed a gap-like depression in the optical conductivity at low frequency along with parallel growth of a broad absorption peak...

Effective Spin-1/2 Hamiltonians Determined for Er2Ti2O7 & Yb2Ti2O7 Through Inelastic Neutron Scattering

We used time-of-flight inelastic neutron scattering to measure the excitation spectra from field-polarized states of exotic frustrated magnets. A knowledge of these spin-wave excitations in various directions in reciprocal space allows a robust determination of exchange parameters in suitable model Hamiltonians.  We have taken this approach with two pyrochlores, Er2Ti2O7 and Yb2Ti2O7, whose magnetic properties have until this point been somewhat puzzling.  The model we use is an effective spin-1/2 exchange Hamiltonian that incorporates the full...

Perturbative String Theory

Octonionic Symmetry

Emergence of Supergroups from Junctions of M-branes

We study the boundary conditions in the topologically twisted Chern-Simons matter theories with the Lie 3-algebraic structure. We find that the supersymmetric boundary conditions and the gauge invariant boundary conditions can be unified as the complexified gauge invariant boundary conditions which lead to the supergroup WZW models. We examine the BPS indices of the supergroup WZW models which may describe certain junctions of M2-branes and M5-branes by identifying the vacuum configurations of the brane system...

Array Site Reports 3

Array Site Reports cont.

Aspects of 6d (1,0) theories and their toroidal reduction to 4d - Michele Del Zotto

I am going to discuss applications of String/M/F theory dualities to argue about the toroidal compactification to four dimensions of 6d (1,0) theories.

Entangling with Topological Quantum Matter

Topological phases of matter serve as one of the most striking examples of the richness and novelty of quantum systems with many degrees of freedom.  In contrast to conventional matter, they are characterized by both non-local properties and non-classical notions such as entanglement.  I will discuss two broad categories of topological phases, distinguished by whether or not they possess fractionalized “anyon” excitations that are neither bosons nor fermions.  I will demonstrate that entanglement not only...

Analytic Bootstrap Bounds

Three-dimensional mirror symmetry: a mathematical perspective

Modified gravity, degravitation and equivalence principle


Detection of vacuum entanglement in an ion trap

Quantum information methods have been recently used for studying the properties of ground state entanglement in several many body and field theory systems. We will discuss a thought experiment wherein entanglement can be extracted from the vacuum of a relativistic field theory into a pair of arbitrarily spatially separated atoms. In order to simulate the detection process, we will consider the ground state of a linear chain of cooled trapped ions, and discuss a scheme...

Closed string tachyon dynamics

Given the difficulty of studying time-dependent processes in string theory, closed string tachyon condensation problems are often modelled by the process of renormalization group flow on the world-sheet. But what is the quantitative relation between these two processes? In this talk I will give a partial answer to this question, and discuss what it teaches us about closed string tachyon dynamics.


Coalgebras, Models and Logics for Quantum Systems

Coalgebras are a flexible tool commonly used in computer science to model abstract devices and systems. Coalgebraic models also come with a natural notion of logics for the systems being modelled. In this talk we will introduce coalgebras and aim to illustrate their usefulness for modelling physical systems. Extending earlier work of Abramsky, we will show how a weakening of the usual morphisms for coalgebras provides the flexibility to model quantum systems in an easy to motivate manner. We...

Introduction to Anomalies in Quantum Field Theory

Registration Year

  • 2022

Resource Types

  • Audiovisual


  • Perimeter Institute