Regensburg 1998 – scientific programme

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TT: Tiefe Temperaturen

TT 20: Korrelierte Elektronen (Theorie) I

TT 20.2: Talk

Thursday, March 26, 1998, 15:00–15:15, H 18

SO(5) Symmetrie in wechselwirkenden Leitern — •Enrico Arrigoni and Werner Hanke — Institut für Theoretische Physik Universität Würzburg, D-97074 Würzburg

We study the occurrence of SO(5) symmetry [1,2] in the low-energy sector of a two-chain (ladder) system [3] by analyzing the flow of the couplings (g-ology) under renormalization group in the weak-interaction limit. In the case of nearest-neighbor hopping, the couplings flow to a SO(5)-invariant manifold at half filling [4]. We extend this analysis by introducing an additional source of explicit SO(5)-breaking symmetry through the inclusion of a next-nearest-neighbor hopping t′. It is shown that SO(5) symmetry is approximately restored by the renormalization-group even in the t′≠0-case provided one accounts for a different single-particle renormalization factor for the quasiparticles on the two bands of the system. We discuss the implications for real two-dimensional systems.

[1] S.C. Zhang, Science 275, 1089 (97)

[2] R. Eder, W. Hanke, and S.C. Zhang, cond-mat/9707233

[3] S.C. Zhang, D. Scalapino and W. Hanke, preprint

[4] L. Balents, M. P. A. Fisher, and H. Lin, preprint