A University of Oklahoma graduate student is the first recipient of a national award from the American Physical Society for outstanding dissertation in theoretical particle physics. Andre Lessa attended OU on the Brazil CAPES Fulbright Fellowship from 2008 to 2011.
The APS J.J. and Noriko Sakurai Dissertation Award in Theoretical Particle Physics recognizes exceptional young scientists who have performed original doctoral thesis work of outstanding scientific quality and achievement in the area of theoretical particle physics. Lessa will present results from his thesis at a special awards session of the spring APS meeting in Atlanta, Ga. on April 3.
Lessa performed work on his doctoral thesis under the supervision of Howard Baer, Homer L. Dodge Professor of High Energy Physics. During his time at OU, Lessa published 13 scholarly articles on aspects of particle physics and cosmology in various international journals. He defended his thesis in July 2011 and graduated from OU in August 2011.
Most in the physics community believe "dark matter" or the dominant form of matter that fills the universe is comprised of weakly interacting massive particles or WIMP particles. Searches for WIMPS include the IceCube neutrino telescope located at the South Pole, space spaced antimatter and gamma-ray detections, noble liquid detectors located a mile or more deep underground, and the Large Hadron Collider at CERN.
Lessa's thesis explores dark matter as a mixture of two different particles: the axion, which is predicted by an elegant solution (Peccei-Quinn or PQ symmetry) to a vexing problem in nuclear physics known as the strong CP problem and the lightest particle of supersymmetry (LSP) theories. The dark matter that arises out of just PQ symmetry or just supersymmetry (SUSY) seems beset by problems.
By including both PQ and SUSY in his thesis, a much more intricate picture of dark matter emerges. Lessa calculates production rates for mixed axion/LSP dark matter in the early universe and matches to observed values. He shows that mixed axion/LSP dark matter ameliorates the above mentioned problems and goes on to discuss how to test the theory based on WIMP and axion detection experiments and via SUSY searches at the LHC.
Lessa was selected for this award from a distinguished field of nominees that included students from many Ivy League universities. He is currently a postdoctoral associate at the University of Sao Paolo in Brazil.