Exact electronic Green functions in a Luttinger liquid with long-range interactions

We compute the 2-point (equal-time) electronic Green function in a Tomonaga-Luttinger system with long-range electron-electron interactions. We obtain an analytical expression for a "super long-range" potential of the form $V(x)=\frac{e^2d^{-\epsilon}}{|x|^{1-\epsilon}}$. As a consistency check of our computational technique we also consider the particular case of a Coulomb potential. Our result confirms the $\exp-C(logx)^{3/2}$ long-distance behavior first obtained by Schulz.Comment: Latex, 11 pages, no figures. Version to appear in Phys. Rev. B. Added references, corrected sign and factor in equations (19) and (21

On a CFT prediction in the sine-Gordon model

A quantitative prediction of Conformal Field Theory (CFT), which relates the second moment of the energy-density correlator away from criticality to the value of the central charge, is verified in the sine-Gordon model. By exploiting the boson-fermion duality of two-dimensional field theories, this result also allows to show the validity of the prediction in the strong coupling regime of the Thirring model.Comment: 5 pages, no figures, late

Critical behavior of the spin correlation function in Ashkin-Teller and Baxter models with a line defect

We consider the critical spin-spin correlation function of the Ashkin-Teller and Baxter models. By using path-integral techniques in the continuum description of these models in terms of fermion fields, we show that the correlation decays with distance with the same critical exponent as the Ising model. The procedure is straightforwardly extended to take into account the presence of a line defect. Thus we find that in these altered models the critical index of the magnetic correlation on the defect coincides with the one of the defective 2D Ising or Bariev's model.Comment: Expanded explanations. Added references. Accepted for publication in Phys. Rev.

Voltage profile and four terminal resistance of an interacting quantum wire

We investigate the behavior of the four-terminal resistance $R_{4pt}$ in a quantum wire described by a Luttinger liquid in two relevant situations: (i) in the presence of a single impurity within the wire and (ii) under the effect of asymmetries introduced by dirty voltage probes. In the first case, interactions leave a signature in a power law behavior of $R_{4pt}$ as a function of the voltage $V$ and the temperature $T$. In the second case interactions tend to mask the effect of the asymmetries. In both scenarios the occurrence of negative values of $R_{4pt}$ is explained in simple terms.Comment: 5 pages, 3 figures; added references, corrected typos, improved explanation

An alternative formulation of classical electromagnetic duality

By introducing a doublet of electromagnetic four dimensional vectorpotentials, we set up a manifestly Lorentz covariant and SO(2) duality invariantclassical field theory of electric and magnetic charges. In our formulation one does not need to introduce the concept of Dirac string.Instituto de Física La Plat

Quantum pump effect in one-dimensional systems of Dirac fermions

We investigate the behavior of the directed current in one-dimensional systems of Dirac fermions driven by local periodic potentials in the forward as well in backscattering channels. We treat the problem with Keldysh non-equilibrium Green's function formalism. We present the exact solution for the case of an infinite wire and show that in this case the dc current vanishes identically. We also investigate a confined system consistent in an annular arrangement coupled to a particle reservoir. We present a perturbative treatment that allows for the analytical expressions of the dc current in the lowest order of the amplitudes of the potential. We also present results obtained from the exact numerical solution of the problem.Comment: 8 pages, 5 figure

Friedel oscillations in a Luttinger liquid with long-range interactions

We introduce a path-integral approach that allows us to compute charge-density oscillations in a Luttinger liquid with impurities. We obtain an explicit expression for the envelope of Friedel oscillations in the presence of arbitrary electron-electron potentials. As examples, in order to illustrate the procedure, we show how to use our formula for contact and Coulomb potentials.Facultad de Ciencias ExactasInstituto de Física La Plat