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The interaction of the light with propagating axial torsion fields in the presence of an external magnetic field has been investigated. Axial torsion fields appearing in higher derivative quantum gravity possess two states, with spin one…
We propose an experiment for detecting Axion-Like Particles (ALPs) based on the axion-photon interaction in the presence of a non-uniform magnetic field. The impact of virtual ALPs on the polarization of the photons inside a cavity is…
The quantum electrodynamical vacuum polarization effects arising in the collision of a high-energy proton beam and a strong, linearly polarized laser field are investigated. The probability that laser photons merge into one photon by…
In this thesis, 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…
The axion particle is the outcome of the proposed Peccei-Quinn mechanism for solving the strong CP problem. Axion is also a popular dark matter candidate. Thus there is an increased interest in establishing its existence. Axions couple to…
Pseudoscalar particles, with almost zero mass and very weak coupling to the visible matter, arise in many extensions of the standard model of particle physics. Their mixing with photons in the presence of an external magnetic field leads to…
Recent work has shown the utility of examining background effects from ultralight dark matter on precision measurements. This effect enhances seemingly benign contributions to the level that experiments are sensitive to them. In this work,…
String theory compactifications may generate many light axion-like particles (ALPs) with weak couplings to electromagnetism. In general, a large number of ALPs may exist, with a linear combination having a potentially observable coupling to…
We present a brief overview of the ongoing searches for the axion particle via its coupling to photons. Both the classical QCD axions and more recently proposed Axion-Like-Particles are considered. Astrophysical bounds on the axion-photon…
A cold relic axion condensate resulting from vacuum misalignment in the early universe oscillates with a frequency \sim m_a, where m_a is the axion mass. We summarize how the properties of photons propagating in such a medium are modified.…
An extension of the Standard Model is studied, in which two new vector bosons are introduced, a first boson $Z'$ coupled to the SM by the usual minimal coupling, producing an enlarged gauge sector in the SM. The second boson $A'$ field, in…
The axion photon system in an external magnetic field, when for example considered with the geometry of the experiments exploring axion photon mixing (which can be represented by a 1+1 effective model) displays a continuous axion-photon…
The dark photon is a massive hypothetical particle that interacts with the Standard Model by kinetically mixing with the visible photon. For small values of the mixing parameter, dark photons can evade cosmological bounds to be a viable…
The measurements of the linear polarisation of visible light from quasars give strong evidence for large-scale coherent orientations of their polarisation vectors in some regions of the sky. We show that these observations can be explained…
We study the phenomenology of the 'companion-axion model' consisting of two coupled QCD axions. The second axion is required to rescue the Peccei-Quinn solution to the strong-CP problem from the effects of colored gravitational instantons.…
The observation of a non-vanishing rotation of linear polarized laser light after passage through a strong magnetic field by the PVLAS collaboration has renewed the interest in light particles coupled to photons. Axions are a species of…
In the first part of the thesis, we revisit the Dine-Fischler-Srednicki-Zhitnisky axion model in light of the recent Higgs LHC results and electroweak precision data. This model is an extension of the two-Higgs-doublet model incorporating a…
Axion-like particles (ALPs) are very light, neutral, spin zero bosons predicted by many theories which try to complete the standard model of elementary particles. ALPs interact primarily with two photons and can generate photon-ALP…
Photons impinging on strong electromagnetic fields can change both momentum and helicity state, due to quantum vacuum polarisation. We investigate these effects in the collision of photons with impulsive PP-waves, which describe e.g. the…
The (pion) decays controlled by axial anomaly imply the specific entanglement between photons having also the counterparts for classical electromagnetic waves. This is also a specific case of Eisnstein-Podolsky-Rosen-Bohm-Aharonov effect.…