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University of Wisconsin–Madison


My research in theoretical high energy physics aims to seek connections between observable particle physics and the domain of fundamental theory.  High energy physics has now entered a new and exciting data-rich era, which began with neutrino oscillation measurements and will reach a new level of excitement with the thorough exploration of the TeV scale at the LHC. The goals of my research are to understand and improve the extent to which the anticipated data from  collider, cosmological, and neutrino detection experiments can probe Planck/string and/or unification scale physics.

My current work focuses on two topics that can be integrated into the broad context of superstring phenomenology:  (i) the theoretical and phenomenological implications of TeV-scale supersymmetry and (ii) the physics of neutrino flavor mixing.

TeV-scale supersymmetry remains, after several decades of study,  one of the best-motivated candidates for new physics that will be probed extensively at the Tevatron and the LHC.  Given the theoretical advantages of TeV-scale supersymmetry, I have worked on a variety of topics in this area, from theories with extended gauge and Higgs sectors to aspects of CP violation and flavor physics to implications from cosmology such as quintessence theories.  My primary research interest is to study the mysterious and vast parameter space associated with the supersymmetry breaking sector of such theories.  I have co-authored a review article for Physics Reports on this topic, which can be found here (comments/feedback can be sent to  My current emphasis is to construct theoretically motivated benchmark models that are complementary to the existing models used for collider studies.

Neutrino oscillation experiments have revealed not only that neutrinos are massive, but also that leptons display a striking flavor mixing pattern that is in sharp contrast to that of the quarks, providing a new facet to the already puzzling and exciting area of flavor physics.   My work in this area includes studies of the impact of Cabibbo-sized effects in the lepton sector as expected within the general paradigm of quark-lepton unification, and the hypothesis that the underlying flavor physics is governed by icosahedral symmetry, a non-Abelian discrete group that provides a rich arena for flavor model building.

My complete list of publications can be found on SPIRES.