119184475
Effects of heavy bosonic excitations on QED vacuum
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.
118536666
Aharonov-Bohm Effect and Hidden Photons
Signs of hypothetical light gauge bosons from a hidden sector may appear in Aharonov-Bohm-like experiments. The absence of signal in carried on experiments allow us to set a modest constraint to the mass and coupling constant of these particles. Our findings open the possibility to exploit the leaking of hidden magnetic field in a different setup of experiments.
119352395
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.
73721705
Cold Dark Matter from the Hidden Sector
Weakly interacting slim particles (WISPs) such as hidden photons (HP) and axion-like particles (ALPs) have been proposed as cold dark matter candidates. They might be produced non-thermally via the misalignment mechanism, similarly to cold axions. In this talk we review the main processes of thermalisation of HP and we compute the parameter space that may survive as cold dark matter population until today. Our findings are quite encouraging for experimental searches in the laboratory in the near future.
119279933
NEUTRINO OSCILLATIONS IN A MINIMAL CPT VIOLATION FRAME
The oscillation neutrino problem in the extended standard model with minimal number of parameters is considered. The dispersion relations with explicit neutrino–antineutrino asymmetry are discussed and an explanation to the MINIBooNE and solar neutrino controversy is offered. Bounds for the CPT violation symmetry are also found.
118864167
Cosmic Neutrino Background as a Ferromagnet
Abstract If cosmic background neutrinos interact very weakly with each other, through spin–spin interactions, then they may have experienced a phase transition, leading to a ferromagnetic ordering. The small magnetic field resulting from ferromagnetic ordering – if present before galaxy formation – could act as a primordial seed of the magnetic fields observed in several galaxies. Our findings suggest that the magnetization could occur in the right epoch, if the exchange boson of neutrino–neutrino interaction is a massless boson beyond the Standard Model, with a coupling constant of 2.2 × 10 − 13 ( m ν 10 − 4 eV ) 2 g 2.3 × 10 − 7 . The estimation of the magnetic seed is 2.3 × 10 − 27 G ≲ B CNB ≲ 6.8 × 10 − 10 G .
16377160
Topological sectors and gauge invariance in massive vector-tensor theories in D≥4
Abstract A family of locally equivalent models is considered. They can be taken as a generalization to d + 1 dimensions of the Topological Massive and “Self-dual” models in 2+1 dimensions. The corresponding 3+1 models are analized in detail. It is shown that one model can be seen as a gauge fixed version of the other, and their space of classical solutions differs in a topological sector represented by the classical solutions of pure BF model. The topological sector can be gauged out on cohomologically trivial base manifolds but on general settings it may be responsible of the difference in the long distance behaviour of the models. The presence of this topological sector appears explicitly in the partition function of the theories. The generalization of this models to higher dimensions is shown to be straightfoward.
120081041
AN INTERACTING GAUGE THEORY OF CHARGED PARTICLES AND STRINGS
Using a standard procedure we obtain from the pure gauge theory of Nambu for 3-forms, two interaction theories between three antisymmetric gauge fields of different ranks. These theories are non-equivalent and describe the same dynamical system at the classical level. They could be interpreted as describing the interaction between charged and closed strings.