A non covariant fermionic determinant and its connection to Luttinger systems

We consider a fermionic determinant associated to a non covariant Quantum Field Theory used to describe a non relativistic system in (1+1) dimensions. By exploiting the freedom that arises when Lorentz invariance is not mandatory, we determine the heat-kernel regulating operator so as to reproduce the correct dispersion relations of the bosonic excitations. We also derive the Hamiltonian of the functionally bosonized model and the corresponding currents. In this way we were able to establish the precise heat-kernel regularization that yields complete agreement between the path-integral and operational approaches to the bosonization of the Tomonaga-Luttinger model.Facultad de Ciencias ExactasInstituto de Física La Plat

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

Backscattering off a dynamical impurity in one-dimensional Fermi systems: a perturbative computation

We investigate the problem of backscattering off a time-dependent and spatially extended barrier in a one-dimensional noninteracting electron gas. By performing a perturbative expansion in the backscattering amplitude, we compute the total energy density of the system. We show how the free fermion spectrum and the conductance of the system are affected by the interplay between dynamical and geometrical properties of the impurity.Instituto de Física La Plat

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

Critical behavior of the spin correlation function in the 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 two-dimensional Ising or Bariev model.Instituto de Física La Plat

Transient and finite-size effects in transport properties of a quantum wire

We study the time-dependent backscattered current produced in a quantum wire when a local barrier is suddenly switched on. Previous investigations are improved by taking into account the finite length of the device. We establish two different regimes in terms of the relationship between the energy scales associated with the voltage and the length of the system. We show how previous results, valid for wires of infinite length, are modified by the finite size of the system. In particular, our study reveals a rich pattern of temporal steps within which the current suffers an initial relaxation followed by temporary revivals. By employing both analytical and numerical methods we describe peculiar features of this structure. From this analysis one concludes that our results render a recently proposed approach to the determination of the Luttinger parameter, K, more realistic.Facultad de Ciencias ExactasInstituto de Física La Plat

Classical Electromagnetic Field Theory in the Presence of Magnetic Sources

Using two new well-defined four-dimensional potential vectors, we formulate the classical Maxwell field theory in a form which has manifest Lorentz covariance and SO(2) duality symmetry in the presence of magnetic sources. We set up a consistent Lagrangian for the theory. Then from the action principle we obtain both Maxwell's equation and the equation of motion of a dyon moving in the electromagnetic field.Instituto de Física La Plat

A non covariant fermionic determinant and its connection to Luttinger systems

We consider a fermionic determinant associated to a non covariant Quantum Field Theory used to describe a non relativistic system in (1+1) dimensions. By exploiting the freedom that arises when Lorentz invariance is not mandatory, we determine the heat-kernel regulating operator so as to reproduce the correct dispersion relations of the bosonic excitations. We also derive the Hamiltonian of the functionally bosonized model and the corresponding currents. In this way we were able to establish the precise heat-kernel regularization that yields complete agreement between the path-integral and operational approaches to the bosonization of the Tomonaga-Luttinger model.Facultad de Ciencias ExactasInstituto de Física La Plat

Equivalent bosonic theory for the massive Thirring model with a non-local interaction

We study, through path-integral methods, an extension of the massive Thirring model in which the interaction between currents is non-local. By examining the mass expansion of the partition function we show that this non-local massive Thirring model is equivalent to a certain non-local extension of the sine-Gordon theory. Thus, we establish a non-local generalization of the well known Coleman's equivalence. We also discuss some possible applications of this result in the context of one-dimensional strongly correlated systems and finite-size quantum field theories.Facultad de Ciencias Exacta

Backscattering off a dynamical impurity in one-dimensional Fermi systems: a perturbative computation

We investigate the problem of backscattering off a time-dependent and spatially extended barrier in a one-dimensional noninteracting electron gas. By performing a perturbative expansion in the backscattering amplitude, we compute the total energy density of the system. We show how the free fermion spectrum and the conductance of the system are affected by the interplay between dynamical and geometrical properties of the impurity.Instituto de Física La Plat