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Theory Center Seminar Series

Subject:Rho and Sigma Mesons From Chiral and Large Nc Dynamics
Speaker: Enrique Ruiz Arriola, University of Granada
Date:Monday, April 18, 2011
Time:10:00 a.m.
Place:CEBAF Center, Room F113
Abstract:The large Nc and chiral expansions have been used to examine the properties and nature of resonances in pi-pi scattering. I review some important aspects of this problem from different viewpoints.

  1. Phys.Lett.B679:449-453,2009
  2. Phys.Rev.D80:045023,2009
  3. Phys.Rev.D81:054009,2010

Subject:Pi-N Scattering and Pion Photoproduction in a Dynamical Coupled-Channels Model
Speaker: Fei Huang, University of Georgia
Date:Monday, April 25, 2011
Time:1:00 p.m. (coffee at 12:45 p.m.)
Place:CEBAF Center, Room L104
Abstract:The dynamical coupled-channels model developed by the Juelich-Georgia group is presented, which presently includes the gamma-N, pi-N, eta-N and Sigma-K stable channels as well as the effective pi-pi-N channels pi-Delta, rho-N and sigma-N. Recent progress on the description of pi-N --> Sigma-K and pion photoproduction within this model is discussed, with the emphasis given on the gauge invariance of the photoproduction amplitudes.

Subject:The Imbalanced Fermi Gas at Unitarity
Speaker: Olga Goulko, Cambridge, UK
Date:Monday, May 2, 2011
Time:1:00 p.m. (coffee at 12:45 p.m.)
Place:CEBAF Center, Room L104
Abstract:Lattice field theory is a useful tool for studying strongly interacting theories in condensed matter physics. A prominent example is the unitary Fermi gas: a two-component system of fermions interacting with divergent scattering length. With Monte Carlo methods this system can be studied from first principles. In the presence of an imbalance (unequal number of particles in the two components) a sign problem arises, which makes conventional algorithms inapplicable. I will show how to apply reweighting techniques to generalize the recently developed worm algorithm to the imbalanced case, and present results for the critical temperature and other thermodynamic observables at the critical point, namely the chemical potential, the energy per particle and the contact density. I will also present some preliminary results for these observables at temperatures beyond the critical point.