Giardino, S.
2014.
``Axisymmmetric empty space: light propagation, orbits and dark matter''. J. Mod. Phys.. 5(15):1402-1411.
AbstractThis study presents an axisymmetric solution of the Einstein equations for empty space. The geometry is studied by determining its Petrov classification and killing vectors. Light propagation, orbital motion and asymptotic and Newtonian limits are also studied. Additionally, cosmological applications of the geometry are also outlined as an alternative model for the inflationary universe and as a substitute for dark matter and quintessence.
Giardino, S, DeLeo S.
2014.
``Dirac solutions for quaternionic potentials''. J. Math. Phys.. 55(2):022301-10.
AbstractThe Dirac equation is solved for quaternionic potentials, i V0 + j W0 (V0∈ℝ,W0∈ℂ). The study shows two different solutions. The first one contains particle and anti-particle solutions and leads to the diffusion, tunneling, and Klein energy zones. The standard solution is recovered taking the complex limit of this solution. The second solution, which does not have a complex counterpart, can be seen as a V0-antiparticle or |W0|-particle solution.
Giardino, S.
2014.
``The Static String''. Mod. Phys. Lett.. A29(03):1450018.
AbstractIn this paper, the quantum fluctuation of a rigid and static string is reported to be identical to a free quantum particle. Solutions similar to this static string have already been found in the semiclassical quantization of pulsating strings, and our results show that the semiclassical quantization of pulsating strings is, in some cases, a perturbation of static strings. We also interpret the energy of the static string as a lower bound for the pulsating string and speculate about a description of quantum mechanics in terms of semiclassical string theory.
Giardino, S, Teotônio-Sobrinho P.
2013.
``A non-associative quaternion scalar field theory''. Mod. Phys. Lett.. A28(35):1350163., Number 35
AbstractA nonassociative Groenewold–Moyal (GM) plane is constructed using quaternion-valued function algebras. The symmetrized multiparticle states, the scalar product, the annihilation/creation algebra and the formulation in terms of a Hopf algebra are also developed. Nonassociative quantum algebras in terms of position and momentum operators are given as the simplest examples of a framework whose applications may involve string theory and nonlinear quantum field theory.
Giardino, S.
2013.
``Angular invariant quantum mechanics in arbitrary dimension''. Rev. Bras. Ens. Fis.. 35:3307.
AbstractOne dimensional quantum mechanics problems, namely the infinite potential well, the harmonic oscillator, the free particle, the Dirac delta potential, the finite well and the finite barrier are generalized for finite arbitrary dimension in a radially symmetric, or angular invariant, manner. This generalization enables the Schrödinger equation solutions to be visualized for Bessel functions and Whittaker functions, and it also enables connections to multi-dimensional physics theories, like string theory.
Giardino, S.
2013.
``Semi-classical strings in (2+1)-dimensional backgrounds''. ISRN High Energy Phys.. 2013:517858.
AbstractThis study analyzes the geometrical relationship between a classical string and its semiclassical quantum model. From an arbitrary (2+1)-dimensional geometry, a specific ansatz for a classical string is used to generate a semi-classical quantum model. In this framework, examples of quantum oscillations and quantum free particles are presented that uniquely determine a classical string and the space-time geometry where its motion takes place.
Giardino, S, Vicentini G, Isolani PC.
1997.
``Synthesis and characterization of lanthanide picrate complexes with tripiperidinophosphine oxide''. J. Alloys Comp.. 249(1-2):91-93.
AbstractCompounds with the general formula Ln(pic)3·2tpppo (Ln: La-Lu, Y; pic=picrate; tpppo=tripipendinophosphine oxide) were synthesized by reaction of the hydrated picrates with tpppo in absolute ethanol. IR absorption spectra were interpreted in terms of the coordination of tpppo through the oxygen and picrate anions that are bidentate, coordinated to the central ions through the phenoxo group and one oxygen of an ortho-nitro group. Conductance measurements in acetonitrile solutions show that the complexes behave as non-electrolytes. X-ray powder patterns show only one isomorphous series. Phosphorus-31 NMR showed a signal shift to lower field with relation to the free ligand, showing evidence of bonding through the phosphoryl group. The parameters obtained from the absorption spectrum of the Nd compound indicate that the metal-ligand bonds present some covalent character. The emission spectra of the europium and samarium adducts were determined. The spectrum of the europium compound was interpreted in terms of D2d distorted towards C2v symmetry for the Eu(O)8 chromophore.