Mecanismo de aceleração de Fermi modificado por termos de violação da simetria de Lorentz

Abstract

The Standard Model Extension (SME) is an extension of Standard Model (SM) which includes Lorentz and CPT symmetries violating terms in all of its sectors. Motivated by possibility of new effects on known physical systems in literature, this work performs an investigation about possible effects produced by these violation terms in Fermi acceleration mechanism of cosmic rays since understanding the acceleration mechanisms of cosmic rays constitutes an object of many researches in Astrophysics. In order to develop this theme, firstly it is studied the main features about cosmic rays, such as detection, energy spectrum analysis, Hillas criterion, galactic and extragalactic origin of cosmic rays, propagation and interactions with cosmic microwave background radiation (GKZ limit). Afterwards, it is

discussed about cosmic rays acceleration mechanisms, approaching the top-down and bottom- up scenarios. It is shown how Hillas criterion establishes limitations on possible astrophysical

sites where particles can be accelerated and obtain energy. Hereafter it is explained the basic idea of cosmic rays acceleration due to electromagnetic fields and this section gives two examples of this acceleration mechanism (sunspots and pulsars). Afterward it is derived the famous result of Fermi mechanism and how it was improved by implementing a different scenario constituted by shock fronts. In the last chapters, it is discussed about Lorentz symmetry violation in SME and then this work investigates how the term ̄cμ⌫

⌫@μ deforms the dispersion relations in fermion sector and the possible effects this term can yield in Fermi acceleration mechanism.