Two-Dimensional 3He: A Crucial System for Understanding Fermion Dynamics
Sprache des Titels:
Englisch
Original Kurzfassung:
Abstract = {{Neutron scattering measurements at the Institut Laue-Langevin off
quasi-two-dimensional 3He have shown, for the first time, a situation
where the collective mode crosses the particle-hole continuum and
reappears, at a momentum transfer of q approximate to 1.55 angstrom(-1)
as a well-defined collective excitation (Godfrin et al. in J. Low Temp.
Phys., 2009, in press).
The effect is well described by the Fermion generalization of
multi-particle fluctuation theory of Jackson, Feenberg, and Campbell
that has been so successful for bosonic quantum fluids. We describe the
theory briefly and state that it can be mapped onto the form of
time-dependent Hartree-Fock theory (TDHF) containing energy dependent
effective interactions; these are obtained from microscopic ground state
theory.
Our theoretical result has far-reaching consequences: a popular paradigm
in discussing the density-density response function of Fermi systems is
the ``random phase approximation{''} (RPA), most frequently applied with
some static interaction and, perhaps, some effective mass. Such a
``phenomenologically modified{''} RPA can be justified only under severe
simplifying approximations and is unable to describe the experimental
situation consistently. As soon as one goes beyond the RPA, intermediate
states which cannot be described in terms of the quantum numbers of a
single (quasi-)particle become essential for capturing the correct
physics. In order to understand the above mentioned experiment, their
appropriate inclusion, as presented in this work, is essential.}}
Sprache der Kurzfassung:
Englisch
Journal:
Journal of Low Temperature Physics
Veröffentlicher:
Springer
Volume:
158
Number:
1-2, Sp. Iss. SI
Seitenreferenz:
194-200
Erscheinungsmonat:
1
Erscheinungsjahr:
2010
ISSN:
1573-7357
Anzahl der Seiten:
7
Notiz zur Publikation:
17th International Conference on Quantum Fluids and Solids, Evanston, IL, AUG 05-11, 2009
Forschungs-