Dan Freed, Mike Hopkins, Constantin Teleman, Loop groups and twisted K-theory ,I, II (arXiv:0312155, arXiv:0711.1906, arXiv:0511232)
on loop groups and twisted K-theory. The result on K-groups has been lifted to an equivalence of categories in
Daniel S. Freed, Constantin Teleman, Dirac families for loop groups as matrix factorizations, arxiv/1409.6051
Constantin Teleman, The structure of 2D semi-simple field theories (arXiv)
on 2-dimensional TQFT
Edward Frenkel, Constantin Teleman, A. J. Tolland, Gromov-Witten Gauge Theory I (arXiv)
Dan Freed, Mike Hopkins, Jacob Lurie, Constantin Teleman, Topological Quantum Field Theories from Compact Lie Groups
on quantization of Dijkgraaf-Witten theory and Chern-Simons theory;
Andrew Blumberg, Ralph Cohen, Constantin Teleman, Open-closed field theories, string topology, and Hochschild homology (arXiv:0906.5198)
on string topology and TCFT