Dirac-Weyl equation on a hyperbolic graphene surface under perpendicular magnetic fields

In this paper the Dirac-Weyl equation on a hyperbolic surface of graphene under magnetic fields is considered. In order to solve this equation analytically for some cases, we will deal with vector potentials symmetric under rotations around the z axis. Instead of using tetrads we will get this equation from a more intuitive point of view by restriction from the Dirac-Weyl equation of an ambient space. The eigenvalues and corresponding eigenfunctions for some magnetic fields are found by means of the factorization method. The existence of a zero energy ground level and its degeneracy is also analysed in relation to the Aharonov-Casher theorem valid for at graphene

Classical ladder functions for Rosen-Morse and curved Kepler-Coulomb systems

Producción CientíficaLadder functions in classical mechanics are defined in a similar way as ladder operators in the context of quantum mechanics. In the present paper, we develop a new method for obtaining ladder functions of one dimensional systems by means of a product of two ‘factor functions’. We apply this method to the curved Kepler–Coulomb and Rosen–Morse II systems whose ladder functions were not found yet. The ladder functions here obtained are applied to get the motion of the systems.Ministerio de Economía, Industria y Competitividad (project MTM2014-57129-C2-1-P)Junta de Castilla y León-FEDER (projects BU229P18 / VA057U16 / VA137G18)

Degeneracy in carbon nanotubes under transverse magnetic δ-fields

Física Teórica, Atómica y Óptic

The hyperbolic step potential: Antibound states, SUSY partners and Wigner time delays

Física Teórica, Atómica y Óptic

The anisotropic oscillator on curved spaces: A new exactly solvable model

We present a new exactly solvable (classical and quantum) model that can be interpreted as the generalization to the two-dimensional sphere and to the hyperbolic space of the two-dimensional anisotropic oscillator with any pair of frequencies and . The new curved Hamiltonian depends on the curvature of the underlying space as a deformation/contraction parameter, and the Liouville integrability of relies on its separability in terms of geodesic parallel coordinates, which generalize the Cartesian coordinates of the plane. Moreover, the system is shown to be superintegrable for commensurate frequencies , thus mimicking the behaviour of the flat Euclidean case, which is always recovered in the limit. The additional constant of motion in the commensurate case is, as expected, of higher-order in the momenta and can be explicitly deduced by performing the classical factorization of the Hamiltonian. The known and anisotropic curved oscillators are recovered as particular cases of , meanwhile all the remaining curved oscillators define new superintegrable systems. Furthermore, the quantum Hamiltonian is fully constructed and studied by following a quantum factorization approach. In the case of commensurate frequencies, the Hamiltonian turns out to be quantum superintegrable and leads to a new exactly solvable quantum model. Its corresponding spectrum, that exhibits a maximal degeneracy, is explicitly given as an analytical deformation of the Euclidean eigenvalues in terms of both the curvature and the Planck constant . In fact, such spectrum is obtained as a composition of two one-dimensional (either trigonometric or hyperbolic) Pösch–Teller set of eigenvalues.Física Teórica, Atómica y ÓpticaMinisterio de Economía, Industria y Competitividad (Projects MTM2013-43820-P and MTM2014-57129-C2-1-P)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. BU278U14 and VA057U16

The general Racah algebra as the symmetry algebra of generic systems on pseudo–spheres

We characterize the symmetry algebra of the generic superintegrable system on a pseudo-sphere corresponding to the homogeneous spaceSO(p,q+ 1)/SO(p,q) wherep+q=

Biotransformation of testosterone by Cladosporium sphaerospermum

Incubation of testosterone 1 with Cladosporium sphaerospermum MRC 70266 afforded six metabolites and two of these metabolites, 6?,16?,17?-trihydroxyandrost-4-en-3-one 6 and 6?,12?,17?-trihydroxyandrost-4-en-3-one 7, were determined as new compounds. The fungus mainly hydroxylated testosterone 1 at C-6?, accompanied by some minor hydroxylations at C-7?, C-12?, C-15? and C-16?. A minor oxidation at C-17 and a minor 5?-reduction were also observed