This series consists of talks in the area of Quantum Fields and Strings.
In gauge theories, there is an inherent tension between locality and gauge invariance. This is precisely expressed by the failure to factorize the physical Hilbert space into local tensor products.
Abstract TBA
The two-point functions <O^n(x) Obar^n(y)> for generator O of Coulomb branch chiral rings in D=4 N=2 SCFT will be determined universally to all orders in 1/n by the theory's a-anomaly.
The calculation will be done using the method of large-charge expansion presented in [1706.05743]; the absence of F-terms in the (R-charge)^(-1) expansion of the effective action ensures this universality.
I will also comment on the non-universal and non-perturbative corrections to the two-point functions whose leading piece was numerically shown to go as O(exp(-sqrt(n))).
In this talk I will review the results of recent work in collaboration with Cecilia De Fazio, Benjamin Doyon and István M. Szécsényi. We studied the entanglement of excited states consisting of a finite number of particle excitations. More precisely, we studied the difference between the entanglement entropy of such states and that of the ground state in a simple bi-partition of a quantum system, where both the size of the system and of the bi-partition are infinite, but their ratio is finite.
In the context of the AdS(4)/BCFT(3) correspondence, we study the holographic entanglement entropy for spatial regions having arbitrary shape. An analytic expression for the subleading term with respect to the area law is discussed. When the bulk spacetime is a part of AdS(4),
this formula becomes the Willmore functional with a proper boundary term evaluated on the minimal surface viewed as a submanifold of the three dimensional flat Euclidean space with a boundary.
I will argue that in the context of string theory, the Big Bang singularity of standard and inflationary cosmology is automatically resolved. To see this at the level of an effective field theory, ideas from "Double Field Theory" are useful.
I describe recent progress in classifying 5d N=1 field theories with interacting UV superconformal fixed points (i.e. 5d SCFTs). In the first part of the talk, I review a newly proposed catalog of candidate (simple) gauge theories which captures theories missed by prior field theoretic classification efforts. In the second part of the talk, I discuss a classification program for rank 1 and 2 5d SCFTs in terms of Calabi-Yau 3-folds, along with prospects for its extension to arbitrary rank.
I will present a brief introduction to non-Lorentzian geometries, an important example of such geometries being Newton-Cartan geometry and its torsionful generalization, which is the natural geometry to which non-relativistic field theories couple to. The talk will subsequently review how such geometries have in recent years appeared in gravity, string theory and holography. In particular, torsional Newton-Cartan geometry has been shown to appear as the boundary geometry for Lifshitz spacetimes.
Generically, a small amount of matter introduced to anti-de Sitter spacetime leads to formation of a black hole; however, the high degree of symmetry of AdS means that some initial distributions of matter (possibly also technically generic) oscillate indefinitely.
Polyakov’s bootstrap programme aims at solving conformal field theories using
unitarity and conformal symmetry. Its implementation in two dimensions has been
highly successful and numerical studies, in particular of the 3-dimensional Ising
model, have clearly demonstrated the potential for higher dimensional theories.
Analytical results in higher dimensions, however, require significant insight
into the conformal group and its representations. Surprisingly little is actually