Prof. Thomas Mehen works primarily on Quantum Chromodynamics (QCD) and the application of effective field theory to problems in hadronic physics. Effective field theories exploit the symmetries of hadrons to make model independent predictions when the dynamics of these hadrons are too hard to solve explicitly. For example, the properties of a hadron containing a very heavy quark are insensitive to the orientation of the heavy quark spin. Prof. Mehen has used this heavy quark spin symmetry to make predictions for the production and decay of heavy mesons and quarkonia at collider experiments. Another example is the chiral symmetry of QCD which is a consequence of the lightness of the up and down quarks. The implications of this symmetry for the force between nucleons is a subject of Prof. Mehen's research. Prof. Mehen has also worked on effective field theory for nonrelativistic particles whose short range interactions are characterized by a large scattering length. This theory has been successfully applied to low energy two- and three-body nuclear processes. Some of Prof. Mehen's work is interdisciplinary. For example, techniques developed for nuclear physics have been used to calculate three-body corrections to the energy density of a Bose-Einstein condensate whose atoms have large scattering lengths. Prof. Mehen has also worked on novel field theories which arise from unusual limits of string theory. Examples include noncommutative field theories and theories of tachyonic modes on non-BPS branes.