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UID:10003672-1738594800-1738598400@cmsa.fas.harvard.edu
SUMMARY:Topological to Gravitational Leptogenesis\, via Ultra Unification 
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \nSpeaker: Juven Wang (LIMS\, Royal Institution) \nTitle: Topological to Gravitational Leptogenesis\, via Ultra Unification \nAbstract: We propose a new mechanism for leptogenesis\, named Topological Leptogenesis\, in which dark matter consists of topological order\, so gapped anyon excitations decay to generate the Standard Model lepton asymmetry. Topological Leptogenesis is in contrast with the Majorana Leptogenesis and Gravitational Leptogenesis. In the standard Majorana Leptogenesis\, the baryon asymmetry of the present universe is attributed to the leptogenesis from the sterile right-handed neutrino with heavy Majorana fermion mass decaying into the Standard Model leptons in the very early universe\, while the electroweak sphaleron causes baryogenesis at a later time. Gravitational leptogenesis can be regarded as an intermediate step between Majorana particle leptogenesis and topological non-particle leptogenesis. Topological Leptogenesis is derived out of Ultra Unification constructed from a mod 16 nonperturbative global anomaly cancellation that adds a symmetry-extended anomalous gapped topological quantum field theory (TQFT) to the Standard Model. Thus (1) the Beyond-the-Standard-Model (BSM) Dark Matter partly consists of Topological Order with low energy TQFT\, while there are anyon string excitations above the energy gap. (2) The 5th force is a Topological Discrete Gauge Force of (B-L) that mediates between the Standard Model particles\, the BSM Topological Order\, and gapped anyon string non-particle excitations. \nBased on https://arxiv.org/abs/2501.00607\, https://arxiv.org/abs/2012.15860\, https://arxiv.org/abs/2302.14862 and https://arxiv.org/abs/2411.05786.
URL:https://cmsa.fas.harvard.edu/event/qft_2325/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Field Theory and Physical Mathematics
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QFT-and-Physical-Mathematics-2.3.25.png
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UID:10003434-1738600200-1738603800@cmsa.fas.harvard.edu
SUMMARY:Rational approximation and the AAA algorithm
DESCRIPTION:Colloquium \nSpeaker: Nick Trefethen\, Harvard University \nTitle: Rational approximation and the AAA algorithm \nApproximation by rational functions used to be mainly a theoretical subject\, but with the introduction of the AAA algorithm in 2018\, it became computationally practical and indeed easy. The implications for what we can do numerically are enormous. This talk will outline the algorithm and demonstrate its application to a collection of problems. We can also use it to demonstrate the potential theory that underlies the theory of rational approximation\, a topic that goes back to Joseph Walsh here at Harvard a century ago.
URL:https://cmsa.fas.harvard.edu/event/colloquium-2325/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-2.3.2025.png
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