Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 30: CE: Low-dimensional Systems - Models 1
TT 30.10: Talk
Thursday, March 25, 2010, 12:00–12:15, H20
Adapted continuous unitary transformation to treat systems with quasiparticles of finite lifetime — Tim Fischer, Sebastian Duffe, and •Götz S. Uhrig — Lehrstuhl Theoretische Physik I, TU Dortmund, 44221 Dortmund
Generic physical systems display excitations of finite life time. Famous examples are Landau’s Fermi liquid or rotons in 4He. Diagonalization by unitary transforms usually aims at stable excitation of infinite life time. Here we introduce an improved generator for continuous unitary transformations which is particularly suited to describe systems with unstable quasiparticles of finite life time. The general properties of this generator are derived and discussed. To illustrate this approach we investigate the asymmetric antiferromagnetic spin-1/2 Heisenberg ladder which allows for spontaneous triplon decay. The resonance behavior of the decaying triplon is shown explicitly.