35 research outputs found
The effective theory of the Calogero- Sutherland model and Luttinger systems.
We construct the effective field theory of the Calogero-Sutherland model in
the thermodynamic limit of large number of particles . It is given by a
\winf conformal field theory (with central charge ) that describes {\it
exactly} the spatial density fluctuations arising from the low-energy
excitations about the Fermi surface. Our approach does not rely on the
integrable character of the model, and indicates how to extend previous results
to any order in powers of . Moreover, the same effective theory can also
be used to describe an entire universality class of -dimensional
fermionic systems beyond the Calogero-Sutherland model, that we identify with
the class of {\it chiral Luttinger systems}. We also explain how a systematic
bosonization procedure can be performed using the \winf generators, and
propose this algebraic approach to {\it classify} low-dimensional
non-relativistic fermionic systems, given that all representations of \winf
are known. This approach has the appeal of being mathematically complete and
physically intuitive, encoding the picture suggested by Luttinger's theorem.Comment: 13 pages, plain LaTeX, no figures
The extended conformal theory of the Calogero-Sutherland model
We describe the recently introduced method of Algebraic Bosonization of
(1+1)-dimensional fermionic systems by discussing the specific case of the
Calogero-Sutherland model. A comparison with the Bethe Ansatz results is also
presented.Comment: 12 pages, plain LaTeX, no figures; To appear in the proceedings of
the IV Meeting "Common Trends in Condensed Matter and High Energy Physics",
Chia Laguna, Cagliari, Italy, 3-10 Sep. 199
Symmetry Aspects and Finite-Size Scaling of Quantum Hall Fluids
The exactness and universality observed in the quantum Hall effect suggests
the existence of a symmetry principle underlying Laughlin's theory. We review
the role played by the infinite and conformal algebras as
dynamical symmetries of incompressible quantum fluids and show how they predict
universal finite-size effects in the excitation spectrum.Comment: 15 pages, CERN-TH-6784/93, LateX fil
The extended conformal theory of Luttinger systems
We describe the recently introduced method of algebraic bosonization of the
-dimensional Luttinger systems by discussing in detail the specific case
of the Calogero-Sutherland model, and mentioning the hard-core Bose gas. We
also compare our findings with the exact Bethe Ansatz results.Comment: 9 pages, plain Latex file, ,based on a talk given by S. Sciuto at the
II International Sakharov Conference on Physics, Moscow, Russia, 20-24 May 9
Chiral Partition Functions of Quantum Hall Droplets
Chiral partition functions of conformal field theory describe the edge
excitations of isolated Hall droplets. They are characterized by an index
specifying the quasiparticle sector and transform among themselves by a
finite-dimensional representation of the modular group. The partition functions
are derived and used to describe electron transitions leading to Coulomb
blockade conductance peaks. We find the peak patterns for Abelian hierarchical
states and non-Abelian Read-Rezayi states, and compare them. Experimental
observation of these features can check the qualitative properties of the
conformal field theory description, such as the decomposition of the Hilbert
space into sectors, involving charged and neutral parts, and the fusion rules.Comment: 37 pages, 8 figure
Effective Field Theories for Electrons in Crystalline Structures
We present an effective field theory formulation for a class of condensed
matter systems with crystalline structures for which some of the discrete
symmetries of the underlying crystal survive the long distance limit, up to
mesoscopic scales, and argue that this class includes interesting materials,
such as -doped . The surviving symmetries determine a limited set of
possible effective interactions, that we analyze in detail for the case of
-doped materials. These coincide with the ones proposed in the
literature to describe the spin relaxation times for the -doped
materials, obtained here as a consequence of the choice of effective fields and
their symmetries. The resulting low-energy effective theory is described in
terms of three (six chiral) one-dimensional Luttinger liquid systems and their
corresponding intervalley transitions. We also discuss the Mott transition
within the context of the effective theory.Comment: 24 pages, 3 figure
Topological phase transition in a RNA model in the de Gennes regime
We study a simplified model of the RNA molecule proposed by G. Vernizzi, H.
Orland and A. Zee in the regime of strong concentration of positive ions in
solution. The model considers a flexible chain of equal bases that can pairwise
interact with any other one along the chain, while preserving the property of
saturation of the interactions. In the regime considered, we observe the
emergence of a critical temperature T_c separating two phases that can be
characterized by the topology of the predominant configurations: in the large
temperature regime, the dominant configurations of the molecule have very large
genera (of the order of the size of the molecule), corresponding to a complex
topology, whereas in the opposite regime of low temperatures, the dominant
configurations are simple and have the topology of a sphere. We determine that
this topological phase transition is of first order and provide an analytic
expression for T_c. The regime studied for this model exhibits analogies with
that for the dense polymer systems studied by de GennesComment: 15 pages, 4 figure
Neutral modes edge state dynamics through quantum point contacts
Dynamics of neutral modes for fractional quantum Hall states is investigated
for a quantum point contact geometry in the weak-backscattering regime. The
effective field theory introduced by Fradkin-Lopez for edge states in the Jain
sequence is generalized to the case of propagating neutral modes. The dominant
tunnelling processes are identified also in the presence of non-universal
phenomena induced by interactions. The crossover regime in the backscattering
current between tunnelling of single-quasiparticles and of agglomerates of
p-quasiparticles is analysed. We demonstrate that higher order cumulants of the
backscattering current fluctuations are a unique resource to study
quantitatively the competition between different carrier charges. We find that
propagating neutral modes are a necessary ingredient in order to explain this
crossover phenomena.Comment: 28 pages, 5 figure