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Deconfined Quantum Multicriticality

Speaker
Ryan Thorngren
Date
Mon March 9th 2026, 2:00 - 3:30pm
Affiliation
UCLA
Event Sponsor
Leinweber Institute for Theoretical Physics at Stanford
Location
Varian 355

I will discuss the multicritical point in the Fradkin-Shenker model, also known as the toric code in an in-plane field. This multicritical point does not admit any Landau-Ginzburg description, but I will show how to describe it using Nf = 2 QED3. This revives an old proposal for deconfined quantum criticality in the easy-plane Neel-VBS transition, which turned out to be first order. Instead, we will find a deconfined quantum multicritical point, with the 1st order nature of the Neel-VBS transition explaining the famous duality-breaking line in the Fradkin-Shenker model. I will also discuss multicritical versions of the duality with the easy-plane CP1 model, and a U(1) symmetric version of the Fradkin-Shenker model.This talk is based on recent work with Pierluigi Niro and Thomas Dumitrescu - https://arxiv.org/abs/2602.23420