PAIR EXCITATIONS AND VERTEX CORRECTIONS IN FERMI FLUIDS AND THE DYNAMIC STRUCTURE FUNCTION OF TWO-DIMENSIONAL 3He
| Autor: | Matthias Meschke, Martin Panholzer, Helga M. Böhm, Henri Godfrin, Hans J. Lauter, Eckhard Krotscheck |
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| Přispěvatelé: | Institute for Theoretical Physics [Linz], Johannes Kepler Universität Linz (JKU), Ultra-basses températures (UBT), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Institut Laue-Langevin (ILL), ILL |
| Rok vydání: | 2007 |
| Předmět: |
correlated basis functions
Quantum fluid Physics 3He Statistical and Nonlinear Physics Fermion multi-pair excitations Polarization (waves) Condensed Matter Physics Roton 01 natural sciences density response function 010305 fluids & plasmas Fermi fluids Effective mass (solid-state physics) Self-energy Dispersion relation Quantum mechanics 0103 physical sciences [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el] 010306 general physics Quantum Excitation Boson |
| Zdroj: | International Journal of Modern Physics B International Journal of Modern Physics B, World Scientific Publishing, 2007, 21 (13-14), pp.2055-2066. ⟨10.1142/S0217979207043464⟩ |
| ISSN: | 1793-6578 0217-9792 |
| DOI: | 10.1142/s0217979207043464 |
| Popis: | We use the equations–of–motion approach for time–dependent pair correlations in strongly interacting Fermi liquids to develop a theory of the excitation spectrum and the single–particle self energy in such systems. We present here the fully correlated equations and their approximate solutions for 3 He . Our theory has the following properties: It reduces to both, i) the "correlated" random–phase approximation (RPA) for strongly interacting fermions if the two–particle–two–hole correlations are ignored, and, ii) to the correlated Brillouin–Wigner perturbation theory for boson quantum fluids in the appropriate limit. iii) It preserves the two first energy–weighted sum rules, and systematically improves upon higher ones. iv) A familiar problem of the standard RPA is that it predicts a roton energy that lies more than a factor of two higher than what is found in experiments. A popular cure for this is to introduce an effective mass in the Lindhard function. No such ad–hoc assumption is invoked in our work. We demonstrate that the inclusion of correlated pair–excitations improves the dispersion relation significantly. Finally, a novel form of the density response function is derived that arises from vertex corrections in the proper polarization. |
| Databáze: | OpenAIRE |
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