Paola Arias

CPT / Lorentz invariance violation and neutrino oscillation

We analyze the consequences of violation of Lorentz and CPT invariance in the massless neutrino sector by deforming the canonical anti-commutation relations for the fields. We show that, for particular choices of the deformation, oscillation between massless neutrino species takes place when only Lorentz invariance is violated. On the other hand, if both Lorentz and CPT invariances are violated, we show that there is no oscillation between massless neutrino species. Comparing with the existing experimental data on neutrino oscillations, we obtain bounds on the parameter for Lorentz invariance violation.

Chiral anomaly beyond Lorentz invariance

The chiral anomaly in the context of an extended standard model with Lorentz invariance violation is studied. Taking into account bounds from measurements of the speed of light, we argue that the chiral anomaly and its consequences are general results valid even beyond the relativistic symmetry.

N=2 SUSY Abelian Higgs model with hidden sector and BPS equations

A bstractIn this paper we study a system inspired on certain SUSY breaking models and on more recent Dark Matter scenarios. In our set-up, two Abelian gauge fields interact via an operator that mixes their kinetic terms. We find the extended Supersymmetric version of this system, that also generates a Higgs portal type of interaction. We obtain and study both analytically and numerically, the equations defining topologically stable string-like objects. We check our results using two different approaches.

Geometric aspects of the dipolar interaction in lattices of small particles

The hysteresis curves of systems composed of small interacting magnetic particles, regularly placed on stacked layers, are obtained with Monte Carlo simulations. The remanence as a function of temperature, in interacting systems, presents a peak that separates two different magnetic states. At low temperatures, small values of remanence are a consequence of antiferromagnetic order due to the dipolar interaction. At higher values of temperature the increase of the component normal to the lattice plane is responsible for the small values of remanence. The effect of the number of layers, coordination number and distance between particles are investigated.

Chern–Simons–Higgs theory with visible and hidden sectors and its N=2 SUSY extension

We study vortex solutions in Abelian Chern-Simons-Higgs theories with visible and hidden sectors. We rst

Hidden Photons in Aharonov-Bohm-Type Experiments

We discuss the Aharonov-Bohm effect in the presence of hidden photons kinetically mixed with the ordinary electromagnetic photons. The hidden photon field causes a slight phase shift in the observable interference pattern. It is then shown how the limited sensitivity of this experiment can be largely improved. The key observation is that the hidden photon field causes a leakage of the ordinary magnetic field into the supposedly field-free region. The direct measurement of this magnetic field can provide a sensitive experiment with a good discovery potential, particularly below the

Effects of heavy bosonic excitations on QED vacuum

\sim

SU(2) kinetic mixing terms and spontaneous symmetry breaking

meV mass range for hidden photons.

A two particle hidden sector and the oscillations with photons

We discuss the contribution of axion-like excitations (ALE) to the vacuum birefringence in the limit mA ≳ ω, where mA is the mass of the excitation and ω the energy of test photons interacting with an external (intense) magnetic field. The relevance of this term with respect to the QED contribution depends on the ratio gA/mA and, from present bounds on the mass and the coupling constant gA, we find that in the present low energy regime, it ranges from 10-14 to 102 suggesting an interesting alternative to explore.

Generalized Dirac duality and CP violation in a two-photon theory

The non-Abelian generalization of the Holdom model, i.e. a theory with two gauge fields coupled to the kinetic mixing term g tr(Fμν(A)Fμν(B)) is considered. Contrarily to the Abelian case, the group structure G×G is explicitly broken to G. For SU(2) this fact implies that the residual gauge symmetry as well as the Lorentz symmetry is spontaneously broken. We show that this mechanism provides masses for the involved particles. Also, the model presents instanton solutions with a redefined coupling constant.