University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Thursday, September 18th 2014
12:15 pm:
Speaker: Haruki Watanabe (U. California, Berkeley)
Subject: Nambu-Goldstone bosons in nonrelativistic systems

Spontaneous symmetry breaking is a very universal phenomenon seen in both relativistic and nonrelativistic systems. When it occurs in nonrelativistic situations, such as magnets and cold spinor BECs, there is a variety in the spectrum of gapless excitations even when the symmetry breaking patterns are the same as Lorentz invariant cases. We develop an effective Lagrangian to understand the number and the dispersion of Goldstone bosons in general. The effective Lagrangian is also useful to understand the dynamics of topological defects and skyrmions. We will also talk about interactions between Goldstone bosons and nonrelativistic fermions (electrons in solids with a Fermi surface), which sometimes result in the breakdown of the Fermi-liquid description and overdamping of Goldstone bosons.

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