Talks will talk place on Thursdays at 2:00pm in the 5th floor SCGP common room, unless stated otherwise in the announcement.
Schedule:
| Date | Name | Title | Abstract |
| Sept 04 2025 | Alexander Frenkel | Confusions about Matrices and Black Holes and Emergent Gravity | I will selfishly co-opt this journal club to talk about a list of questions (and confusions) that interest me regarding emergent geometry from matrix quantum mechanics, that I am hoping to work on in the near future or simply have someone tell me the answer to. I will start with a pedagogical review/introduction, then the range of topics will roughly include (some subset of): the role of non-singlet excitations in black hole entropy and eigenvalue distributions for models with multiple matrices, ER = EPR and transitions in topology of the emergent space, the emergence of the black hole interior, and how to set up and study quantum singularities. |
| Sept 11 2025 | Arkya Chatterjee | Non-invertible self-duality symmetries in qudit models | The self-duality of the 1+1d quantum Ising model under gauging its Z_2 symmetry underlies the non-invertible Kramers-Wannier symmetry of its critical point. This has a natural generalization to self-dual Hopf algebras, which will be the main subject of this talk. Along the way, we will discuss how Hopf qudits realize all 1+1d anomaly-free finite generalized symmetries in lattice models with tensor product Hilbert spaces. Allowing the symmetry algebra on the lattice to mix with translation symmetry further leads us to a large family of anomalous non-invertible symmetries. We will contextualize this discussion with the Kac-Paljutkin algebra H_8, writing down some simple Hamiltonians that enjoy the associated self-duality symmetry. |
| Sept 18 2025 | Vasilii Iugov | Yang-Mills flows and magic angles in Twisted Bilayer Graphene | I will discuss the Yang–Mills flow on the space of connections on a two-torus and its application to the problem of magic angles. In the chiral limit, the TBG Hamiltonian reduces to a two-dimensional chiral Dirac operator coupled to an SU(2) gauge field parametrized by the twist angle. In this framework, magic angles correspond to unstable SU(2) connections. I will compute the codimension of the subspace of unstable connections and show that, once rotational symmetry of TBG is taken into account, it matches the codimension of the set of magic angles. The talk is based on 2504.19097, joint with Nikita Nekrasov. |
| Sept 25 2025 | |||
| Oct 2 2025 | Alessio Miscioscia | PT, Lee–Yang model and all that | Taking the Lee–Yang edge singularity as a prototypical example of a non-unitary conformal field theory, I will review recent progress on non-unitary RG flows in two dimensions, with particular emphasis on the role of PT symmetry. I will present the generalization of the Lee-Yang model to its multicritical versions and, as a consequence, I will describe how the Zamolodchikov’s flows extend to the non-unitary case. All these predictions can be explicitly tested through Hamiltonian truncation methods (see 2211.01123, 2304.08522). |
| Oct 16 2025 | Jake McNamara | New Non-BPS Objects in String Theory | The Swampland Cobordism Conjecture predicts the existence of many new, stable, non-BPS branes and defects in well-known string theories. After reviewing the logic behind the Cobordism Conjecture, I will give a survey of what is currently known about these new objects. I will then focus on two particular objects: the domain wall between Type IIA and IIB, and the reflection 7-branes of either Type II theory. Though much is not known about these objects, I will describe recent progress in characterizing their kinematics and the relationship between them. |
| Oct 23 2025 | Sebastian Harris | Holographic Interfaces in Symmetric Product Orbifolds | Symmetric product orbifolds provide a controlled environment for exploring generic features of gauge theory and holography. The tractability of these 2d CFTs relies on the complete characterisation of their gauge structure through holomorphic covering maps. This talk introduces a novel class of generalised covering maps that define a universal family of conformal interfaces between symmetric product orbifolds. The holographic nature of these interfaces is established by constructing an ensemble whose spectrum of local excitations matches the known spectrum of open strings on AdS2 branes in the tensionless limit of pure NSNS string theory on AdS3xS3xT4. Because both sides of the correspondence are fully solvable, this matching can be carried out exactly, offering strong evidence for the duality. As further evidence, correlators of the holographic ensemble of interfaces are shown to structurally match string perturbation theory to all orders in the string coupling. |
| Oct 27 | Adrian Lopez | Categorical ‘t Hooft expansion and chiral algebras | In https://arxiv.org/abs/2411.00760, we show how holographic dual B-model backgrounds can be systematically derived from the ‘t Hooft expansion of specific families of chiral algebras. The resulting holographic dual backgrounds are typically non-commutative and appear to be novel. In this talk I’ll review certain aspects of our construction. In particular, we’ll review how we construct a category of D-branes for the dual String Theory, starting from the planar limit of the chiral algebra. Given its generality, I’ll emphasize the potential utility of the construction in the study of weak coupling holography for general theories with a large N limit. |
| Oct 31 at 1:40 in room 102 | Maria Nocchi | A double-copy picture of strings in AdS | The Kawai–Lewellen–Tye (KLT) relations are a striking example of how string theory can reveal hidden structures and connect a web of, in principle, very different theories. Originally, they state that (tree-level) closed-string amplitudes can be expressed as quadratic combinations of open-string amplitudes. In the field theory limit, this gives rise to the celebrated double-copy between gluons and gravitons. In this talk, we will explore how much of this elegant structure persists when we move from flat space to AdS. As a first step, I will propose the fundamental building blocks of tree-level open- and closed-string amplitudes in AdS and show how they are related via an AdS version of the KLT relations. This structure not only significantly simplifies explicit calculations but also points to deeper algebraic and geometric structures that remain to be uncovered. |
| Nov 6 2025 | |||
| Nov 13 2025 | |||
| Nov 20 2025 | Keith Glennon | E11 Symmetries in M Theory | We review the argument that E11 is a symmetry of m-theory at low energies. We will suggest the possibility of an E11 symmetry based on dimensionally reduced coset symmetries of 11D SUGRA. We will argue that a certain induced representation of the semi-direct product of the very extended algebra E8+++ = E11, with its vector representation, results in the equations of motion of the bosonic sector of m-theory at low energies, predicting additional effects beyond the supergravity approximation. We will then review recent developments illustrating K27 as the 26D closed bosonic string analogue of E11, and future questions. |
| Nov 27 2025 | |||
| Dec 5 2025 | Shehab Fadda | ||
| Nov 12 2025 | Xuchen Cao | ||
| Nov 19 2025 |