Non-relativistic classical mechanics for spinning particles

We study the classical dynamics of non-relativistic particles endowed with spin. Non-vanishing Zitterbewegung terms appear in the equation of motion also in the small momentum limit. We derive a generalized work-energy theorem which suggests classical interpretations for tunnel effect and quantum potential

Black hole dynamical evolution in a Lorentz-violating spacetime

We consider the black hole dynamical evolution in the framework of a Lorentz-violating spacetime endowed with a Schwarzchild-like momentum-dependent metric. Large deviations from the Hawking-Bekenstein predictions are obtained, depending on the values of the Lorentz-violating parameter lambda introduced. A non-trivial evolution comes out, following mainly from the existence of a non-vanishing minimum mass: for large Lorentz violations, most of the black hole evaporation takes place in the initial stage, which is then followed by a stationary stage (whose duration depends on the value of lambda) where the mass does not change appreciably. Furthermore, for the final stage of evolution, our model predicts a sweet slow death of the black hole, whose "slowness" again depends on lambda, in contrast with the violent final explosion predicted by the standard theory.Comment: 8 pages, 8 figure

Fundamental times, lengths and physical constants: some unknown contributions by Ettore Majorana

We review the introduction in physics of the concepts of an elementary space length and of a fundamental time scale, analyzing some related unknown contributions by Ettore Majorana. In particular, we discuss the quasi-Coulombian scattering in presence of a finite length scale, as well as the introduction of an intrinsic (universal) time delay in the expressions for the retarded electromagnetic potentials. Finally, we also review a special model considered by Majorana in order to deduce the value of the elementary charge, in such a way anticipating key ideas later introduced in quantum electrodynamics.Comment: 10 page

Deriving Spin within a discrete-time theory

We prove that the classical theory with a discrete time (chronon) is a particular case of a more general theory in which spinning particles are associated with generalized Lagrangians containing time-derivatives of any order (a theory that has been called "Non-Newtonian Mechanics"). As a consequence, we get, for instance, a classical kinematical derivation of Hamiltonian and spin vector for the mentioned chronon theory (e.g., in Caldirola et al.'s formulation).Comment: 10 pages; LaTeX fil

Generalized Ginzburg-Landau models for non-conventional superconductors

We review some recent extensions of the Ginzburg-Landau model able to describe several properties of non-conventional superconductors. In the first extension, s-wave superconductors endowed with two different critical temperatures are considered, their main thermodynamical and magnetic properties being calculated and discussed. Instead in the second extension we describe spin-triplet superconductivity (with a single critical temperature), studying in detail the main predicted physical properties. A thorough discussion of the peculiar predictions of our models and their physical consequences is as well performed.Comment: 16 pages, 2 figure

A new dielectric effect in viscous liquids

An accurate experimental and theoretical study has been performed about a phenomenon, not previously reported in the literature, occurring in highly viscous liquids: the formation of a definite pipe structure induced by the passage of a heavy body, this structure lasting for quite a long time. A very rich phenomenology (including mechanical, optical and structural effects) associated with the formation of the pipe has been observed in different liquids. Actually, the peculiar dynamical evolution of that structure does not appear as a trivial manifestation of standard relaxation or spurious effects. In particular we have revealed different time scales during the evolution of the pipe and a non-monotonous decrease of the persistence time with decreasing viscosity (with the appearance of at least two different maxima). We put forward a microscopic model, consistent with the experimental data, where the pipe behaves as a "dielectric shell" whose time evolution is described through a simple thermodynamical approach, predicting several properties effectively observed.Comment: 14 pages, 6 figures. arXiv admin note: text overlap with arXiv:0812.436

Spin and Madelung fluid

Starting from the Pauli current we obtain the decomposition of the non-relativistic local velocity in two parts: one parallel and the other orthogonal to the momentum. The former is recognized to be the ``classical'' part, that is the velocity of the center-of-mass, and the latter the ``quantum'' one, that is the velocity of the motion in the center-of-mass frame (namely, the internal ``spin motion'' or {\em Zitterbewegung}). Inserting the complete expression of the velocity into the kinetic energy term of the classical non-relativistic (i.e., Newtonian) Lagrangian, we straightforwardly derive the so-called ``quantum potential'' associated to the Madelung fluid. In such a way, the quantum mechanical behaviour of particles appears to be strictly correlated to the existence of spin and Zitterbewegung

Baryon asymmetry in the Universe resulting from Lorentz violation

We analyze the phenomenological consequences of a Lorentz violating energy-momentum dispersion relation in order to give a simple explanation for the baryon asymmetry in the Universe. By assuming very few hypotheses, we propose a straightforward mechanism for generating the observed matter-antimatter asymmetry which entails a Lorentz-breakdown energy scale of the order of the Greisen-Zatsepin-Kuzmin cut-off.Comment: 7 page