# Exact chiral symmetries of Hamiltonian lattice fermions in 3+1d

- Institution: CERN
- Department: TH String Theory Seminar
- Speaker: Ryan Thorngren
- Year: 2025
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3022445)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

We will discuss methods of circumventing the fermion doubling problem in 3+1d Hamiltonian lattice models. In particular, we will construct a 3+1d model with a single Weyl fermion and an exact UV symmetry which implies the conservation of chiral charge in the IR. We will do the same for the SU(2) symmetry of a single Weyl doublet, finding a connection between an object in integrability known as the Onsager algebra, and Witten's SU(2) anomaly. Time permitting, we will also discuss 2+1d models with the parity anomaly.

This talk is based on https://arxiv.org/abs/2503.07708 with Lei Gioia (Caltech)

(online talk) .

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## Lectures

1. [Exact chiral symmetries of Hamiltonian lattice fermions in 3+1d](https://invisiblenetwork.ai/learn/cern/3022445/147b273db31a), 1 h 14 min (CERN's player)