Saïd Business School are delighted to extend an invitation to attend the annual Rewley Lecture.
The lecture will this year be held on the 19th February in the Sheldonian Theatre. We’ll be joined by Biz Stone (pictured), co-founder of Twitter, and Evan Sharp, co-founder of Pinterest to deliver the lecture titled ‘Reconnecting with the Sacred in a Technology-Driven World’.
Symmetry Enhancement, SPT Absorption, and Duality in QED_3
Abstract
Abelian gauge theories in 2+1 dimensions are very interesting QFTs: they are strongly coupled and exhibit non-trivial dynamics. However, they are somewhat more tractable than non-Abelian theories in 3+1 dimensions. In this talk, I will first review the known properties of fermions in 2+1 dimensions and some conjectures about QED_3 with a single Dirac fermion. I will then present the recent proposal from [arXiv:2409.17913] regarding the phase diagram of QED_3 with two fermions. The findings reveal surprising (yet compelling) features: while semiclassical analysis would suggest two trivially gapped phases and a single phase transition, the actual dynamics indicate the presence of two distinct phase transitions separated by a "quantum phase." This intermediate phase exists over a finite range of parameters in the strong coupling regime and is not visible semiclassically. Moreover, these phase transitions are second-order and exhibit symmetry enhancement. The proposal is supported by several non-trivial checks and is consistent with results from numerical bootstrap, lattice simulations, and extrapolations from the large-Nf expansion.