Broken U(1) symmetry and excitations in Bose liquids
نویسنده
چکیده
We consider the low-energy effective field theory at finite temperature of Bose condensed liquids (e.g., superfluid 4He). A most general model-independent effective Lagrangian is derived directly from the breakdown of the global symmetry U(1). We show that it can yield one form of Landau quantum hydrodynamic Hamiltonian. In order to demonstrate its usefulness, this effective Lagrangian is employed to derive the momentum and temperature dependence of the damping of excitations by means of power counting. The result of it is shown to be model independent, and is obtained in a much simpler way than before. PACS: 67.40.Db, 11.15.Ex, 05.30.Jp
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Broken U(1) gauge symmetry and excitations in Bose liquids
We derive the low-energy effective field theory at finite temperature of Bose condensed liquids (e.g., superfluid 4He) directly from the breakdown of the global gauge symmetry U(1). The theory can immediately yield the Landau quantum hydrodynamics. The Bogoliubov type spectrum of low-energy collective excitations is given in the zeroth order of this theory and the momentum and temperature depen...
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