arXiv subjects

Sergio Severini

Publications and source records attributed to Sergio Severini.

3 recordsLinked to original sources

arXiv2012

Solenoidality of a Magnetic Induction Field and Conservation of Total Momentum

This scientific essay proposes to discuss the physical aspects of a system consisting of some non-relativistic massive charged particles, that are the sources in motion of an electromagnetic field (e.m.) propagating through the space, filled by a linear, homogeneous, and isotropic material medium. The physical link between the conservation of total momentum and the solenoidality of a magnetic induction field is investigated. After a careful review of all the more widely sustained didactic justifications for the solenoidality of magnetic induction, some properties of the Maxwell e.m. stress tensor are defined according to Minkowski. This study presents a new framework wherein the necessary condition for the free-divergence of magnetic induction in the entire space, here named as solenoidality condition, derives directly from the total momentum conservation of the system, i.e. particles plus field. The theoretical treatise generally leads to results that leave some open questions on the existence, or at least the observability, of the magnetic monopoles. Their observability is theoretically plausible only under suitable assumptions of symmetry that, in the opinion of authors, may be in any case an interesting topic of scientific discussion especially in the field of experimental physics.

physics.class-ph↗

arXiv2008

Which group velocity of light in a dispersive medium?

The interaction between a light pulse, traveling in air, and a generic linear, non-absorbing and dispersive structure is analyzed. It is shown that energy conservation imposes a constraint between the group velocities of the transmitted and reflected light pulses. It follows that the two fields propagate with group velocities depending on the dispersive properties of the environment (air) and on the transmission properties of the optical structure, and are one faster and the other slower than the incident field. In other words, the group velocity of a light pulse in a dispersive medium is reminiscent of previous interactions. One example is discussed in detail.

physics.optics↗

arXiv2005

Lorentz Beams

A new kind of tridimensional scalar optical beams is introduced. These beams are called Lorentz beams because the form of their transverse pattern in the source plane is the product of two independent Lorentz functions. Closed-form expression of free-space propagation under paraxial limit is derived and pseudo non-diffracting features pointed out. Moreover, as the slowly varying part of these fields fulfils the scalar paraxial wave equation, it follows that there exist also Lorentz-Gauss beams, i.e. beams obtained by multipying the original Lorentz beam to a Gaussian apodization function. Although the existence of Lorentz-Gauss beams can be shown by using two different and independent ways obtained recently from Kiselev [Opt. Spectr. 96, 4 (2004)] and Gutierrez-Vega et al. [JOSA A 22, 289-298, (2005)], here we have followed a third different approach, which makes use of Lie's group theory, and which possesses the merit to put into evidence the symmetries present in paraxial Optics.

physics.optics↗