Phase transitions in Zn gauge models: Towards quantum simulations of the Schwinger-Weyl QED

Year: 2018

Authors: Ercolessi E., Facchi P., Magnifico G., Pascazio S., Pepe F.V.

Autors Affiliation: Univ Bologna, Dipartimento Fis & Astron, I-40127 Bologna, Italy; INFN, Sez Bologna, I-40127 Bologna, Italy; Univ Bari, Dipartimento Fis, I-70126 Bari, Italy; Univ Bari, MECENAS, I-70126 Bari, Italy; INFN, Sez Bari, I-70126 Bari, Italy; CNR, INO, I-50125 Florence, Italy.

Abstract: We study the ground-state properties of a class of Z(n) lattice gauge theories in 1 + 1 dimensions, in which the gauge fields are coupled to spinless fermionic matter. These models, stemming from discrete representations of the Weyl commutator for the U(1) group, preserve the unitary character of the minimal coupling and have, therefore, the property of formally approximating lattice quantum electrodynamics in one spatial dimension in the large-n limit. The numerical study of such approximated theories is important to determine their effectiveness in reproducing the main features and phenomenology of the target theory, in view of implementations of cold-atom quantum simulators of QED. In this paper, we study the cases n = 2 divided by 8 by means of a DMRG code that exactly implements Gauss’s law. We perform a careful scaling analysis and show that, in absence of a background field, all Z(n) models exhibit a phase transition which falls in the Ising universality class, with spontaneous symmetry breaking of the CP symmetry. We then perform the large-n limit and find that the asymptotic values of the critical parameters approach the ones obtained for the known phase transition of the zero-charge sector of the massive Schwinger model, which occurs at negative mass.

Journal/Review: PHYSICAL REVIEW D

Volume: 98 (7)      Pages from: 74503-1  to: 74503-16

More Information: The authors are grateful to Fabio Ortolani for his help with the DMRG code. E.E., P.F., G.M. and S.P. are partially supported by Istituto Nazionale di Fisica Nucleare (INFN) through the project QUANTUM. F.V.P. is supported by INFN through the project PICS. P.F. is partially supported by the Italian National Group of Mathematical Physics (GNFM-INdAM).
KeyWords: lattice; fermions; spin; gases; systems
DOI: 10.1103/PhysRevD.98.074503

Citations: 63
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