[Speaker] Prof. Eckart Meiburg, Distinguished Professor, University of California at Santa-Barbara

Speaker: Prof. Mahendra Verma, Dept of Physics & Kotak School of Sustainability, Indian Institute of Technology Kanpur, India

Seminar by Dr. Luca Gennaioli, University of Warwick

Enric Solé-Farré (Beijing Institute of Mathematical Sciences and Applications): October 26, 4pm-5pm, lecture room L5D23.

Title: Spin(7) Bubbles and Flops under Cohomogeneity-One Assumptions

Abstract: In this talk, I will discuss geometric transitions and gauge theory on complete noncompact Spin(7) spaces with Aloff–Wallach principal orbits. Cohomogeneity-one symmetry reduces both the torsion-free Spin(7) equations and the invariant gauge theory equations to dynamical systems, providing a setting in which metric degenerations and curvature concentration can be visualised and studied explicitly.
On the gauge-theoretic side, I will describe the construction and moduli problem of invariant Spin(7)-instantons, including a compactification model incorporating both metric and gauge-theoretic bubbles. On the metric side, we will describe three families of asymptotically locally conical metrics, and describe bubble-like behaviour as in the gauge theoretic side. In particular, we will outline how two of the metrics are related by a Spin(7)-flop in the orbifold category, following the expectations of the physicists Cvetic--Gibbons--Lu--Pope and earlier results of Lehmann.
Based on joint work with Hanci Chi.

Guest Seminar hosted by CDQT.
Speaker: Dr.Thore Posske(University of Hamburg)
Title: Synthesizing quantum matter with magnetic and nonmagnetic adatoms on superconductors — the topological secrets of hybridizing Machida-Shibata states
 

Dr. Caroline L. Monteil, Senior Researcher at Aix-Marseille University, CEA, CNRS, Biosciences and Biotechnologies Institute of Aix-Marseille, Saint-Paul-lez-Durance, France

Michael Lathwood (OIST): October 19, 4pm-5pm, lecture room L5D23.

Title: Counting Tensor Invariants with Defect TQFT 

Abstract: A tensor transforming under a unitary-orthogonal symmetry group carries finitely many invariant observables of each degree. Counting these so-called tensor invariants is an important problem in the theory of tensor models, and it reduces to counting tuples of permutations modulo a conjugation action.

In this talk, I will explain how this counting can be interpreted as the partition function of an untwisted Dijkgraaf-Witten topological quantum field theory with defects. The permutations groups appearing in the tensor invariant counting problem are exactly the defect data of a stratified manifold, and the tensor invariant is then the groupoid cardinality of the associated gauge groupoid. I conclude with physics applications coming from this perspective of tensor invariants.

This talk is based on forthcoming joint work with Remi Cocou Avhou, Noan Botcazou-Brasse, and Reiko Toriumi. 

[Seminar] "Direct measurement of coupling distance by Flash & Freeze-fracture replica labeling" by Prof. Ryuichi Shigemoto, Institute of Science and Technology Austria (ISTA)

November 27, 2026  11:00-12:00 @L5D23

Title: From dislocation dynamics to Hamilton-Jacobi equations: homogenization and the Orowan mechanism

Speaker: Dr. Panrui Ni (Waseda University)

Seminar by Prof. Spatafora