Ian Affleck (University of British Columbia): Condensed Matter Physics/Field Theory
Title: 2 Dimensional Non-linear Sigma Models with Topological Terms and Quantum Spin Chains (2 talks)
The 2016 Nobel Prize was awarded to Duncan Haldane in part for his “Haldane conjecture”. Based on mapping quantum spin chains of spin magnitude s into the O(3) non-linear sigma model with topological angle theta =2 pi s, he argued that the models are gapless (massless) for half-integer s, corresponding to theta =pi but are gapped (massive) for integer s corresponding to theta =0. This was a surprising conclusion, not only for quantum spin chains but also for non-linear sigma models. In my first talk, I will review this field theory mapping and its implications for quantum spin chains. In my second talk I will present a very recent extension to SU(3) chains and a corresponding non-linear sigma model with SU(3) symmetry which has topological terms.
Jose Aguayo (University of Concepcion, Chile): Nonarchimedean Functional Analysis
Title: The p-adic numbers as alternative model for theoretical physics
On a quantum scale the smallest unit is the Planck scale, which is a discrete measure. But there are several speculations that say that the phenomenon can be completely disordered, and one of the most important mathematical laws, the Archimedean axiom, might be violated. Since the fields of p-adic numbers are disordered as well as non-Archimedean it seems appropriate to exploit such fields in this sense. We will start showing how the p-adic numbers field and its extension, including the complex p-adic numbers, have been used in physical-mathematical theory. The rest of the talk will be dedicated to show the field of the p-adic numbers Q_p, its metrical and topological aspects and its algebraic closure, C_p.
Keshav Dasgupta (McGill University): String Theory
Title: Can we solve strongly coupled supersymmetric gauge theories using gravity duals? (first talk)
In this talk we will elaborate how to use gravity duals to study strongly coupled gauge theories with N = 2 and N = 1 supersymmetries. These supersymmetric theories will in general not be scale invariant theories.
Title: How hard is it to get a de Sitter solution in string theory? (second talk)
In this talk I'll discuss how to get a de Sitter solution in string theory. I will discuss the no go theorems associated to getting a positive cosmological solution from string theory, and elaborate on what possible implication it may have for the KKLT type solutions.
Fabian Grusdt (Harvard): Condensed Matter Physics/Quantum Optics
Title: Unraveling many-body physics with quantum impurities
Studying mobile quantum impurities provides a unique perspective on strongly correlated many-body systems. On the one hand, impurities can be used as experimentally accessible coherent probes. For example, this allows to measure exotic non-local observables in systems with topological order. Specifically we demonstrate for Abelian fractional quantum Hall states how the many-body Chern number can be obtained which specifies the effective field theory describing the state. On the other hand, mobile impurities can be an essential part of the many-body system itself. This is the case for example in the most intriguing part of the phase diagram of cuprates, where mobile holes moving in an anti-ferromagnetic environment can be considered as impurities. When their density is high enough, high-temperature superconductivity can be realized. We argue that studying individual holes in this system may provide a promising starting point for the formulation of a unifying effective field theory of cuprates.
Scott Watson (Syracuse University): Cosmology
Title: Naturalness in Cosmology (first talk)
I will provide an overview of effective field theory techniques in cosmology with an emphasis on inflation and dark energy.
Title: Reheating in the Effective Field Theory of Inflation (second talk)
The Effective Field Theory (EFT) of inflation utilizes the importance of symmetries to provide a systematic way in which to classify inflationary models and establish their observational predictions. The required symmetries, along with existing observational constraints (particularly the lack of primordial non-gaussianity at CMB scales), place rigid restrictions on the allowed operators of the EFT. In this talk I discuss what (if any) such restrictions imply for reheating after inflation. Reheating is far less studied than inflation itself and I also discuss how new EFT techniques may be useful in performing a systematic study of inflationary reheating.