# Regensburg 2019 – wissenschaftliches Programm

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# TT: Fachverband Tiefe Temperaturen

## TT 60: Quantum-Critical Phenomena (joint session TT/DY)

### TT 60.2: Vortrag

### Donnerstag, 4. April 2019, 15:15–15:30, H23

**Studies of Deconfined Quantum Criticality in a Half-filled Laudau Level** — •Zhenjiu Wang^{1}, Matteo Matteo Ippoliti^{2}, Roger S. K Mong^{3}, Michael P Zaletel^{2,4}, and Fakher F Assaad^{1} — ^{1}Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany — ^{2}Department of Physics, Princeton University, Princeton, NJ 08544, USA — ^{3}Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA — ^{4}Department of Physics, University of California, Berkeley, CA 94720, USA

We perform Quantum Monte Carlo studies of deconfined quantum criticality (DQC) based on models of interacting fermions.
As opposed to previous studies, this suggests an emergent SO(5) symmetry at criticality, our model has an exact SO(5) symmetry at the Hamiltonian level. This relies on the fact that our model is defined in the continuum. As opposed to lattice regularization, that would break the SO(5) symmetry, we follow a suggestion by [1], where the ultra-violet cutoff is realized by a magnetic field. Our model corresponds to 4 flavors of fermions with Hilbert space restricted to the zeroth Landau level (ZLL) of 8 component Dirac fermions as realized in Graphene, which maps to a nonlinear sigma model containing only bosonic degrees of freedom is studied, with the competition between the stiffness and an SO(5) Wess-Zumino-Witten topological term. AFQMC studies are free of the negative sign problem due to the existence of two anti-unitary particle-hole transformations that leaves the propagator invariant for each MC configuration.

Ippoliti et al., arXiv:1810.00009 (2018)