Spectral moment sum rules for the retarded Green’s function and self-energy of the inhomogeneous Bose-Hubbard model in equilibrium and nonequilibrium

J. K. Freericks,1,* V. Turkowski,2,† H. R. Krishnamurthy,3,4,‡ and M. Knap5 1Department of Physics, Georgetown University, Washington, D.C. 20057, USA 2Physics Department and Nanoscience Technology Center, University of Central Florida, Orlando, Florida 32816, USA 3Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India 4Condensed Matter Theory Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India 5Institute of Theoretical and Computational Physics, Graz University of Technology, 8010 Graz, Austria (Received 19 August 2012; published 24 January 2013)