Multivalued fields and monopole operators in topological superconductors

摘要

In this work, we investigate the role of multivalued fields in the formulation of monopole operators and their connection with topological states of matter. In quantum field theory it is known that certain states describe collective modes of the fundamental fields and are created by operators that are often non-local, being defined over lines or higher-dimensional surfaces. For this reason, they may be sensitive to global, topological, properties of the system and depend on nonperturbative data. Such operators are generally known as monopole operators. Sometimes they act as disorder operators because their nonzero expectation values define a disordered vacuum associated with a condensate of the collective modes, also known as defects. In this work we investigate the definition of these operators and their relation to the multivalued properties of the fundamental fields. We study several examples of scalar field theories and generalize the discussion to p-forms, with the main purpose of studying new field configurations that may be related to topological states of matter. We specifically investigate the so-called chiral vortex configurations in topological superconductors. We highlight an important aspect of this formalism, which is the splitting of the fields in their regular and singular parts that identifies an ambiguity that can be explored, much like gauge symmetry, in order to define observables. (C) 2020 Elsevier Inc. All rights reserved.