Física de momentos de dipolo elétrico e magnético limitando acoplamentos não mínimos que violam a simetria de Lorentz

Abstract

In this work we investigate electric dipole moments (EDMs) and magnetic dipole moments (MDMs) in scenarios with Lorentz symmetry violation (LV). We begin by generally describing the standard model and the EDMs and MDMs in the usual case, as well as the Schiff’s theorem, which poses difficulties in their detection. After this, we explore the effects of nonminimal couplings, arising from the tensor (kF )μ⌫↵# of the CPT-even electrodynamics of the standard model extension (SME), in the Dirac equation on the EDMs and MDMs, besides pondering the generated terms’ detectability. The sidereal analysis of the LV terms is also performed. Next, we repeat this investigation over a class of nonminimal couplings that generate EDM and MDM via a tensor Tμ⌫, with no symmetry in its indices at first. The possible couplings are put forward in hermitian forms and proposals for detection are made. Following this, we considered a modified Coulomb potential and calculated its effect on the Schiff moment: a residual interaction term that circumvents the shielding (predicted by the Schiff’s theorem) due to the atomic nucleus’ finite size. We concluded that the residual term absorbs the modified Coulomb potential’s anisotropies, which are due to the Lorentz symmetry violation in the SME’s CPT-even electrodynamics. In the next chapter, we considered another source of EDM: P- and T-odd couplings between electrons and nucleons (protons and neutrons). After outlining how to obtain the EDM contribution from a coupling in the usual case, we listed general classes of couplings with LV tensors of rank-1 to rank-2. Once these were listed, classified according to their behavior under C, P and T, and applyied the nonrelativistic limit for the nucleons, their EDMcontributions were calculated and their magnitudes limited according to recent experimental data. Whenever applicable, the sidereal analysis was performed on terms with spatial indices in the LV tensors.