143 research outputs found
Topological and Universal Aspects of Bosonized Interacting Fermionic Systems in (2+1)d
General results on the structure of the bosonization of fermionic systems in
d are obtained. In particular, the universal character of the bosonized
topological current is established and applied to generic fermionic current
interactions. The final form of the bosonized action is shown to be given by
the sum of two terms. The first one corresponds to the bosonization of the free
fermionic action and turns out to be cast in the form of a pure Chern-Simons
term, up to a suitable nonlinear field redefinition. We show that the second
term, following from the bosonization of the interactions, can be obtained by
simply replacing the fermionic current by the corresponding bosonized
expression.Comment: 29 pages, RevTe
Non-perturbative approach to backscattering off a dynamical impurity in 1D Fermi systems
We investigate the problem of backscattering off a time-dependent impurity in
a one-dimensional electron gas. By combining the Schwinger-Keldysh method with
an adiabatic approximation in order to deal with the corresponding out of
equilibrium Dirac equation, we compute the total energy density (TED) of the
system. We show how the free fermion TED is distorted by the backscattering
amplitude and the geometry of the impurity.Comment: 5 pages, 2 figures, RevTex4. Appendix and some text added. Results
and conclusions did not change. Version accepted for publication in Phys.
Rev.
On the Electromagnetic Response of Charged Bosons Coupled to a Chern-Simons Gauge Field: A Path Integral Approach
We analyze the electromagnetic response of a system of charged bosons coupled
to a Chern-Simons gauge field. Path integral techniques are used to obtain an
effective action for the particle density of the system dressed with quantum
fluctuations of the CS gauge field. From the action thus obtained we compute
the U(1) current of the theory for an arbitrary electromagnetic external field.
For the particular case of a homogeneous external magnetic field, we show that
the quantization of the transverse conductivity is exact, even in the presence
of an arbitrary impurity distribution. The relevance of edge states in this
context is analyzed. The propagator of density fluctuations is computed, and an
effective action for the matter density in the presence of a vortex excitation
is suggested.Comment: LaTex file, 27 pages, no figure
A gauge invariant and string independent fermion correlator in the Schwinger model
We introduce a gauge invariant and string independent two-point fermion
correlator which is analyzed in the context of the Schwinger model (QED_2). We
also derive an effective infrared worldline action for this correlator, thus
enabling the computation of its infrared behavior. Finally, we briefly discuss
possible perspectives for the string independent correlator in the QED_3
effective models for the normal state of HTc superconductors.Comment: 14 pages, LaTe
Single Superfield Representation for Mixed Retarded and Advanced Correlators in Disordered Systems
We propose a new single superfield representation for mixed retarded and
advanced correlators for noninteracting disordered systems. The method is
tested in the simpler context of Random Matrix theory, by comparing with well
known universal behavior for level spacing correlations. Our method is general
and could be especially interesting to study localization properties encoded in
the mixed correlators of Quantum Hall systems.Comment: 13 pages including two figures, RevTex4. Improved version. Figures
changed. To appear in Journal of Physics
Non-perturbative behavior of the quantum phase transition to a nematic Fermi fluid
We discuss shape (Pomeranchuk) instabilities of the Fermi surface of a
two-dimensional Fermi system using bosonization. We consider in detail the
quantum critical behavior of the transition of a two dimensional Fermi fluid to
a nematic state which breaks spontaneously the rotational invariance of the
Fermi liquid. We show that higher dimensional bosonization reproduces the
quantum critical behavior expected from the Hertz-Millis analysis, and verify
that this theory has dynamic critical exponent . Going beyond this
framework, we study the behavior of the fermion degrees of freedom directly,
and show that at quantum criticality as well as in the the quantum nematic
phase (except along a set of measure zero of symmetry-dictated directions) the
quasi-particles of the normal Fermi liquid are generally wiped out. Instead,
they exhibit short ranged spatial correlations that decay faster than any
power-law, with the law and we
verify explicitely the vanishing of the fermion residue utilizing this
expression. In contrast, the fermion auto-correlation function has the behavior
. In this regime we also find that, at
low frequency, the single-particle fermion density-of-states behaves as
, where is larger
than the free Fermi value, N(0), and is a constant. These results confirm
the non-Fermi liquid nature of both the quantum critical theory and of the
nematic phase.Comment: 20 pages, 2 figures, 1 table; new version with minor changes; new
subsection 3C2 added with an explicit calculation of the quasiparticle
residue at the nematic transition; minor typos corrected, new references;
general beautification of the text and figure
Generalized sine-Gordon/massive Thirring models and soliton/particle correspondences
We consider a real Lagrangian off-critical submodel describing the soliton
sector of the so-called conformal affine Toda model coupled to
matter fields (CATM). The theory is treated as a constrained system in the
context of Faddeev-Jackiw and the symplectic schemes. We exhibit the parent
Lagrangian nature of the model from which generalizations of the sine-Gordon
(GSG) or the massive Thirring (GMT) models are derivable. The dual description
of the model is further emphasized by providing the relationships between
bilinears of GMT spinors and relevant expressions of the GSG fields. In this
way we exhibit the strong/weak coupling phases and the (generalized)
soliton/particle correspondences of the model. The case is also
outlined.Comment: 22 pages, LaTex, some comments and references added, conclusions
unchanged, to appear in J. Math. Phy
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