title: Boundary Effective Action for Quantum Hall States.
abstract: We consider quantum Hall states on a space with boundary, focusing on the aspects of the edge physics which are completely determined by the symmetries of the problem. There are four distinct terms of Chern-Simons type that appear in the low-energy effective action of the state. Two of these protect gapless edge modes. They describe Hall conductance and, with some provisions, thermal Hall conductance. The remaining two, including the Wen-Zee term, which contributes to the Hall viscosity, do not protect gapless edge modes but are instead related to the local boundary response fixed by symmetries. We highlight some basic features of this response. It follows that the coefficient of the Wen-Zee term can change across an interface without closing a gap or breaking a symmetry.
authors.affiliation: Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA.|Kadanoff Center for Theoretical Physics and Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Andrey
authors.initials: A
authors.lastname: Gromov
authors.affiliation: C.N. Yang Institute for Theoretical Physics, SUNY Stony Brook, Stony Brook, New York 11794, USA.
authors.forename: Kristan
authors.initials: K
authors.lastname: Jensen
authors.affiliation: Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA.|Simons Center for Geometry and Physics, Stony Brook University, Stony Brook, New York 11794, USA.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Abanov