Tue, 30 Jan 2024
12:30
L4

Towards the large-charge sector of the critical O(N) model with an interface defect

Vito Pellizzani
(Bern)
Further Information

In conformal field theories, special classes of operators, such as defects and local operators carrying large quantum numbers, have received a lot of attention in recent years. In this talk, I will present some work in progress regarding the extraction of CFT data in the critical O(N) model with a codimension-one flat defect (interface), paying special attention to the case where local operators in large traceless symmetric representations of O(N) (the so-called 'large-charge operators' in this context) are inserted in the bulk. The talk will include a discussion of certain general features of codimension-one defect CFTs, a small review of the large-charge bootstrap, as well as an overview of the current understanding of the phase diagram of the boundary/interface critical O(N) model.

Mon, 18 May 2020
12:45
Virtual

Compensating strong coupling with large charge -- ZOOM SEMINAR

Susanne Reffert
(Bern)
Abstract

Over the last few years, it has become clear that working in sectors of large global charge leads to significant simplifications when studying strongly coupled CFTs. It allows us in particular to calculate the CFT data as an expansion in inverse powers of the large charge.
In this talk, I will introduce the large-charge expansion via the simple example of the O(2) model and will then apply it to a number of other systems which display a richer structure, such as non-Abelian global symmetry groups.
 

Thu, 06 Dec 2012

17:00 - 18:00
L3

An application of proof theory to lattice-ordered groups

George Metcalfe
(Bern)
Abstract

(Joint work with Nikolaos Galatos.) Proof-theoretic methods provide useful tools for tackling problems for many classes of algebras. In particular, Gentzen systems admitting cut-elimination may be used to establish decidability, complexity, amalgamation, admissibility, and generation results for classes of residuated lattices corresponding to substructural logics. However, for classes of algebras bearing a family resemblance to groups, such methods have so far met only with limited success. The main aim of this talk will be to explain how proof-theoretic methods can be used to obtain new syntactic proofs of two core theorems for the class of lattice-ordered groups: namely, Holland's result that this class is generated as a variety by the lattice-ordered group of order-preserving automorphisms of the real numbers, and the decidability of the word problem for free lattice-ordered groups.

Fri, 27 Jan 2012
09:00
L3

Admissibility and Unification through Natural Duality >

Leonardo Cabrer
(Bern)
Abstract

Dualities of various types have been used by different authors to 
describe free and projective objects in a large
  number of classes of algebras. Particularly, natural dualities provide a 
general tool to describe free objects. In
  this talk we present two interesting applications of this fact. 
  We first provide a combinatorial classification of unification problems 
by their unification type for the
varieties of Bounded Distributive Lattices, Kleene algebras, De Morgan 
algebras. Finally we provide axiomatizations forsingle
and multiple conclusion admissible rules for the varieties of Kleene 
algebras, De Morgan algebras, Stone algebras.

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