arXiv subjects

Agnieszka Kujawa

Publications and source records attributed to Agnieszka Kujawa.

4 recordsLinked to original sources

arXiv2009

Some Properties of the Spin-Polarized Attractive Hubbard Model

The influence of a Zeeman magnetic field on the superconducting characteristics of the attractive Hubbard model was investigated. The ground state and temperature phase diagrams were obtained for a fixed number of particles. Two critical magnetic fields were found for the first order phase transition from the superconducting to the normal state for $n\neq 1$. For some range of parameters a reentrant transition was found and gapless superconductivity was obtained. The significance of the Hartree term was also analyzed.

cond-mat.str-el↗

arXiv2008

A comparison of the cut-off effects for Twisted Mass, Overlap and Creutz fermions at tree-level of Perturbation Theory

In this paper we investigate the cutoff effects at tree-level of perturbation theory for three different lattice regularizations of fermions -- maximally twisted mass Wilson, overlap and Creutz fermions. We show that all three kinds of fermions exhibit the expected $O(a^2)$ scaling behaviour in the lattice spacing. Moreover, the size of these cutoff effects for the considered quantities i.e. the pseudoscalar correlation function $C_{PS}$, the mass $m_{PS}$ and the decay constant $f_{PS}$ is comparable for all of them.

hep-lat↗

arXiv2008

The BCS-BEC crossover and superconductivity in a lattice fermion model with hard core repulsion

We have considered the BCS-BEC crossover at T=0 in the framework of a lattice fermion model (the extended Hubbard model). We have analyzed the case of on-site hard core repulsion ($U=\infty$) and intersite attraction ($W<0$) in a 3D system with extended s-wave pairing symmetry. The mechanisms of density-driven and attraction-strength-driven crossover have been analyzed. We have obtained the ground state phase diagram. The analyzed quantities are: chemical potential, order parameter, coherence length and fraction of condensed particles.

cond-mat.str-el↗

arXiv2008

On the Phase Diagram of Spin-Polarized Attractive Hubbard Model: Weak Coupling Limit

The superfluid properties of the attractive Hubbard model in a Zeeman magnetic field, and in the weak coupling regime have been investigated. The temperature and magnetic field dependencies of the order parameter have been analyzed. Furthermore, the temperature vs. magnetic field and temperature vs. spin polarization phase diagrams for the 2D and 3D lattices have been obtained. For some parameters a reentrant transition has been found.

cond-mat.str-el↗