Schwinger boson symmetric spin liquids of Shastry-Sutherland model

Motivated by recent experimental and numerical evidences of deconfined quantum critical point and quantum spin-liquid states in spin-$1/2$ Heisenberg model on Shastry-Sutherland lattice, we studied possible symmetric spin liquid states and their proximate ordered states under Schwinger boson formalism. We found a symmetric gapped $Z_2$ spin-liquid state for intermediate model parameter $0.66 < J_1/J_2 < 0.71$ under mean-field approximation. The Schwinger boson mean-field picture is partially supported by exact-diagonalization and self-consistent spin wave theory results.Comment: 25 pages, 19 figure