- 01June 1, 2021
- 01June 1, 2021
Title: From Ramanujan to Rokhlin, via quantum groups
Abstract: In this talk, intended for a broad audience, I will describe recent work on new q-series invariants of 3-manifolds labeled by Spin-C structures. While the original motivation for studying these invariants is rooted in topology, they exhibit a number of unexpected properties and connections to other areas of mathematics, e.g. turn out to be characters of logarithmic vertex algebras.
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- 02June 2, 2021
CMSA Quantum Matter in Mathematics and Physics: Ultra Unification: Quantum Fields Beyond the Standard ModelStrong, electromagnetic, and weak forces were unified in the Standard Model (SM) with spontaneous gauge symmetry breaking. These forces were further conjectured to be unified in a simple Lie group gauge interaction in the Grand Unification (GUT). Here I propose a theory beyond the SM and GUT by adding new gapped Topological Phase Sectors consistent with the nonperturbative global anomaly cancellation and cobordism constraints (especially from the baryon minus lepton number B – L, the electroweak hypercharge Y, and the mixed gauge-gravitational anomaly). Gapped Topological Phase Sectors are constructed via symmetry extension, whose low energy contains unitary Lorentz invariant topological quantum field theories (TQFTs): either 3+1d non-invertible TQFT (long-range entangled gapped phase), or 4+1d invertible or non-invertible TQFT (short-range or long-range entangled gapped phase). Alternatively, there could also be right-handed neutrinos, or gapless unparticle conformal field theories, or their combinations to altogether cancel the anomaly. We propose that a new high-energy physics frontier beyond the conventional 0d particle physics relies on the new Topological Force and Topological Matter including gapped extended objects (gapped 1d line and 2d surface operators or defects, etc., whose open ends carry deconfined fractionalized particle or anyonic string excitations). I will also fill in the dictionary between math, QFT, and condensed matter terminology, and elaborate on the global anomalies of Z2, Z4, Z16 classes useful for beyond SM. Work is based on arXiv:2012.15860, arXiv:2008.06499, arXiv:2006.16996, arXiv:1910.14668.
- 03June 3, 2021
CMSA Quantum Matter in Mathematics and Physics: Higher Dimensional Topological Order, Higher Category and A Classification in 3+1DTopological orders are gapped quantum liquid states without any symmetry. Most of their properties can be captured by investigating topological defects and excitations of various dimensions. Topological defects in n dimensions naturally form a (weak) n-category. In particular, anomalous topological order (boundary theory) is described by fusion n-category and anomaly-free topological order (bulk) is described by non-degenerate braided fusion n-category. Holographic principle works for topological orders: boundary always has a unique bulk. Another important property in 3+1D or higher is that point-like excitations must have trivial statistics; they must carry representations of a certain group. Such a “gauge group” is hidden in every higher dimensional topological order. In 3+1D, condensing point-like excitations leads to a canonical boundary which in turn determines the bulk topological order. By studying this boundary, a rather simple classification is obtained: 3+1D topological orders are classified by the above “gauge group” together with some cocycle twists. These ideas would also play an important role in dimensions higher than 3+1D and in the study of higher categories, topological quantum field theories and other related subjects.
- 03June 3, 2021
CMSA Interdisciplinary Science Seminar: Navigating Seas of Change – the Role and Significance of Cross-Disciplinary Research
As atmospheric CO2 levels continue to rise and global and coastal ocean become warmer and more eutrophic as a result of human activities, we need better ways to detect and understand how marine ecosystems are responding to these changes. Until recently, most biological oceanographers relied on shipboard measurements that were limited in their coverage and inadequate to investigate changes at large spatial and temporal scales. With the advent of satellites, autonomous platforms and numerical methods, biological oceanographers are turning to empirical and semi-analytical algorithms to scale limited shipboard measurements from local scales to regional, basin and global scales. While progress has been interdisciplinary research involving collaborations between biological, physical and methodical scientists could help us make rapid advances and mitigate impacts on the livelihoods of coastal communities which are at greatest risk. This presentation will cover a case study from the Arabian Sea in the Indian Ocean and describe the promise and potential of inter-disciplinary research in advancing climate change and ecosystem research for societal benefit.