We report a new type of multicritical point that arises from competition between the Higgs and confinement transitions in a Z_2 gauge system. The phase diagram of the 3d gauge Higgs model has been obtained by Monte-Carlo simulation on large (up to 60^3) lattices. We find the transition lines continue as 2nd-order until merging into a 1st-order line. These findings pose the question of an effective field theory for a multicritical point involving noncommuting order parameters. A similar phase diagram is predicted for the 2-dimensional quantum toric code model with two external fields, h_z and h_x; this problem can be mapped onto an anisotropic 3D gauge Higgs model.
From Quantum Dimers to the $π$-flux Toric Code via Deconfined Multicriticality
International Centre for Theoretical Sciences, Tata Institute of Fundamental Research（国际理论科学中心，塔塔基础研究所）；Department of Engineering and Physics, Karlstad University（卡尔斯特德大学工程与物理系）；Nordita, KTH Royal Institute of Technology and Stockholm University（诺迪塔，皇家理工学院和斯德哥尔摩大学）
From QED$_3$ to Self-Dual Multicriticality in the Fradkin-Shenker Model
Mani L. Bhaumik Institute for Theoretical Physics, Department of Physics and Astronomy, University of California, Los Angeles（加州大学洛杉矶分校曼尼·L·巴乌米克理论物理研究所）；SISSA（的里雅斯特国际高等研究学院）；INFN, Sezione di Trieste（意大利国家核物理研究所的里雅斯特分部）
Self-dual Higgs transitions: Toric code and beyond
Perimeter Institute for Theoretical Physics（perimeter研究所）；Department of Physics and Astronomy, McMaster University（麦克马斯特大学物理与天文学系）；Department of Physics and Astronomy, University of Waterloo（滑铁卢大学物理与天文学系）
Topological BF Theory construction of twisted dihedral quantum double phases from spontaneous symmetry breaking
University of California, Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Université Paris-Saclay（巴黎萨克雷大学）；CNRS（法国国家科学研究中心）；Laboratoire de Physique des Solides（固体物理实验室）
