The Landau problem and nonclassicality

Exploring the concept of the extended Galilei group [Formula: see text]. Representations for field theories in a symplectic manifold have been derived in association with the method of the Wigner function. The representation is written in the light-cone of a de Sitter space–time in five dimensions. A Hilbert space is constructed, endowed with a symplectic structure, which is used as a representation space for the Lie algebra of [Formula: see text]. This representation gives rise to the spin-0 Schrödinger (Klein–Gordon-like) equation for the wave functions in phase space, such that the dependent variables have the content of position and linear momentum. This is a particular example of a conformal theory, such that the wave functions are associated with the Wigner function through the Moyal product. We construct the Pauli–Schrödinger (Dirac-like) equation in phase space in its explicitly covariant form. In addition, we analyze the gauge symmetry for spin-1/2 particles in phase space and show how implement the minimal coupling in this case. We applied to the problem of an electron in an external field, and we recovered the nonrelativistic Landau levels. Finally, we study the parameter of negativity associated with the nonclassicality of the system.

Symplectic Field Theory of the Galilean Covariant Scalar and Spinor Representations

We explore the concept of the extended Galilei group, a representation for the symplectic quantum mechanics in the manifold G, written in the light-cone of a five-dimensional de Sitter space-time in the phase space. The Hilbert space is constructed endowed with a symplectic structure. We study the unitary operators describing rotations and translations, whose generators satisfy the Lie algebra of G. This representation gives rise to the Schr¨odinger (Klein–Gordon-like) equation for the wave function in the phase space such that the dependent variables have the position and linear momentum contents. The wave functions are associated to the Wigner function through the Moyal product such that the wave functions represent a quasiamplitude of probability. We construct the Pauli–Schr¨odinger (Dirac-like) equation in the phase space in its explicitly covariant form. Finally, we show the equivalence between the five-dimensional formalism of the phase space with the usual formalism, proposing a solution that recovers the non-covariant form of the Pauli–Schr¨odinger equation in the phase space.

A short study of a string on a plane: The energy and the effective mass

We investigate the new special class of the finite string on a plane, after the reduction from the relativistic 4D case. The suggested special form of the phase space allows to define the extended Galilei group as a group of the spacetime symmetry for the considered system. The definition of the energy for the studied non-relativistic string through the Cazimir function of this group is suggested. The concept of the effective mass for the investigated dynamical system is introduced. The appearance of strong correlations between the degrees of freedom even on the classical level is discussed.

DEFORMED GALILEI SYMMETRY

A particular deformation of centrally extended Galilei group is considered. It is shown that the deformation influences the rules of constructing the composed systems while one-particle states remain basically unaffected. In particular, the mass appears to be nonadditive.