Events at Physics |
Events During the Week of May 10th through May 17th, 2009
Monday, May 11th, 2009
- Joint HEP-NPAC Seminar
- Title to be announced
- Time: 4:00 pm
- Place: 4274 Chamberlin
- Speaker: David Hertzog, University of Illinois Urbana-Champaign
- Host: Karsten Heeger
- String Theory Seminar
- Title to be announced
- Time: 4:30 pm
- Place: 5280 Chmaberlin Hall
- Speaker: Koji Hashimoto, RIKEN (tentative)
Tuesday, May 12th, 2009
- No events scheduled
Wednesday, May 13th, 2009
- No events scheduled
Thursday, May 14th, 2009
- R. G. Herb Condensed Matter Seminar
- Fermionic spinons in two and three dimensions
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Zhihao Hao, Johns Hopkins University
- Abstract: The low energy elementary excitations of the Heisenberg model are magnons, bosons with integer spin if the system is bipartite and has long range order in the ground state. It has been long conjectured that spinons, fermions with spin one half, are the effective degrees of freedom for spin 1/2 frustrated antiferromagnets. While existence of spinons is well established in one dimension, they remain elusive in higher dimensional systems. In this talk we are going to demonstrate there are fermionic spinons in kagome lattice and hyper-kagome lattice. The spinons are topological excitations and couples strongly to a compact U(1) gauge field. They can also be electrically charged through either magnetostriction or higher order perturbation effects. The spinons interact with each other through an exchange mediated attraction and form tightly bound bosonic pairs. The lowest energy triplet excitation of the ground state breaks one such pair into two free spinons at the energy cost of 0.06J, which is the mechanism responsible for the spin gap of the kagome and hyperkagome lattice.
- Host: Natalia Perkins
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- (Joint with Phenomenology) A New Approach to Flavor (?)
- Time: 1:45 pm
- Place: 4274 Chamberlin
- Speaker: Keith Dienes, University of Arizona
- Abstract: The origin of flavor is one of the biggest mysteries of the Standard Model. Despite more than a half-century of data, we still have essentially no explanation for family replication in the Standard Model. Many theoretical models can incorporate or accommodate this replication, but very few actually explain/predict/require it. In this talk, I will describe some recent work on a possible new approach towards explaining the origin of family replication in the Standard Model.
- Host: Sky Bauman and Lisa Everett
- Joint NPAC Forum/HEP Seminar
- The Fermilab Neutrino Program
- Time: 4:00 pm
- Place: 4274 Chamberlin
- Speaker: Steve Brice, FNAL
- Abstract: There has been a rapid expansion of our knowledge of the neutrino sector in the last decade. Neutrino oscillations have been clearly measured in multiple settings and the mixings and masses are starting to be constrained. Fermilab has been and will continue to be at the heart of this endeavor. The talk will review the current, near term, and future neutrino program at Fermilab. The MiniBooNE, MicroBooNE, and MINOS experiments have and will serve to clarify the picture of oscillations. SciBooNE and MINERvA are making precision measurements of neutrino induced processes that will aid future oscillation experiments as well as further our understanding of neutrino interactions. Looking into the future NOvA and then LBNE will probe in increasing detail the last unmeasured mixing, clarify the ordering of the neutrino masses, and culminate in a search for CP violation in the neutrino sector.
- Host: Karsten Heeger
Friday, May 15th, 2009
- R. G. Herb Condensed Matter Seminar
- Title to be announced
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Michael Weissman, University of Illinois at Urbana-Champaign
- Host: Robert McDermott