No abstract

We address the effect of an anomalous triple gauge boson couplings on a physical observable for the electroweak sector of the Standard Model, when the S U 2 L ⊗ U 1 Y symmetry is spontaneously broken by the Higgs mechanism to U 1 e m . Our calculation is done within the framework of the gauge-invariant, but path-dependent variable formalism is an alternative to the Wilson loop approach. Our result shows that the interaction energy is the sum of a Yukawa and a linear potential, leading to the confinement of static probe charges. The point we wish to emphasize, however, is that the anomalous triple gauge boson couplings ( Z γ γ ) contributes to the confinement for distances on the intranuclear scale.

In this contribution, we re-assess some aspects of axionic electrodynamics by coupling non-linear electromagnetic effects to axion physics. We present a number of motivations to justify the coupling of the axion to the photon in terms of a general non-linear extension of the electromagnetic sector. Our emphasis in the paper relies on the investigation of the constitutive permittivity and permeability tensors, for which the axion contributes by introducing dependence on the frequency and wave vector of the propagating radiation. Also, we point out how the axion mass and the axion-photon-photon coupling constant contribute to a dispersive behavior of the electromagnetic waves, in contrast to what happens in the case of non-linear extensions, when effective refractive indices appear which depend only on the direction of the propagation with respect to the external fields. The axion changes this picture by yielding refractive indices with dependence on the wavelength. We apply our results to the special case of the (non-birefringent) Born-Infeld Electrodynamics and we show that it becomes birefringent whenever the axion is coupled. The paper is supplemented by an appendix, where we follow our own path to approach the recent discussion on a controversy in the definition of the Poynting vector of axionic electrodynamics.

We investigate the effects of the Born–Infeld action on the Abelian sector of the electroweak model. The consequence of this approach is the emergence of anomalous couplings in the neutral sector of the Z-gauge boson and photon. These new couplings consist of quartic interactions of the photon with the Z-particle, as for example, three-photon-and-one-Z vertex. With that, we obtain the decay width of $$Z \rightarrow 3\,\gamma $$ Z → 3 γ from which we impose a bound on the Born–Infeld parameter. Other bounds are also obtained from the photon quartic couplings. Subsequently, we consider the presence of an external uniform magnetic field in connection with this Born–Infeld weak hypercharge model. The magnetic background field yields new kinematic effects, like the kinetic mixing between the photon and the Z-boson, and we obtain thereby the corresponding dispersion relations for the mixed photon-Z-particle system. Finally, we calculate the lowest-order modifications to the interaction energy for the anomalous coupling $$3\gamma -Z$$ 3 γ - Z , within the framework of the gauge-invariant but path-dependent variables formalism. Our results show that the interaction energy contains a linear term leading to the confinement of static probe charges. With the help of the potential that comes out, interparticle forces are estimated.