Gapless edge states of BF field theory and translation-symmetric Z2 spin liquids

Understand

We study possible gapless edge states of translation-symmetric Z2 spin liquids.

• The gapless edge states emerge from dangling Majorana fermions at the boundary.
• We construct a series of mean-field Hamiltonians of Z2 spin liquids on the square lattice; these models can be obtained by generalization of Wen's exactly solvable plaquette model.
• We also study the details of the edge theory of these Z2 spin liquids and find their effective BF theory descriptions.