Dark Energy Content of Nonlinear Electromagnetism

Dark Energy and Emergent Spacetime

A natural geometric framework of noncommutative spacetime is symplectic geometry rather than Riemannian geometry. The Darboux theorem in symplectic geometry then admits a novel form of the equivalence principle such that the electromagnetism in noncommutative spacetime can be regarded as a theory of gravity. Remarkably the emergent gravity reveals a noble picture about the origin of spacetime, dubbed as emergent spacetime, which is radically different from any previous physical theory all of which describe what happens in a given spacetime. In particular, the emergent gravity naturally explain…

Milli-Magnetic Monopole Dark Matter and the Survival of Galactic Magnetic Fields

Dark sectors with Abelian gauge symmetries can interact with ordinary matter via kinetic mixing. In such scenarios, magnetic monopoles of a broken dark $U(1)$ will appear in our sector as confined milli-magnetically charged objects under ordinary electromagnetism. Halo ellipticity constraints are shown to significantly bound the strength of dark magnetic Coulomb monopole interactions. The bound monopole ground state, which in vacuum is stable and has no magnetic charge or moment, is shown to become quantum mechanically unstable in the presence of an external, ordinary magnetic field. If these …

Cosmic Birefringence Test of the Hubble Tension

An early dark energy component consisting of a cosmic pseudo Nambu-Goldstone boson has been recently proposed to resolve the Hubble tension -- the four-sigma discrepancy between precision measurements of the expansion rate of the universe. Here we point out that such an axion-like component may be expected to couple to electromagnetism by a Chern-Simons term, and will thereby induce an anisotropic cosmic birefringence signal in the polarization of the cosmic microwave background (CMB). We show that observations of the rotation-angle power spectrum and cross-correlation with CMB temperature ani…

On degenerate metrics, dark matter and unification

A five-dimensional theory of relativity is presented which suggests that gravitation and electromagnetism may be unified using a degenerate metric. There are four fields (in the four-dimensional sense): a tensor field, two vector fields and a scalar field, and they are unified with a combination of a gauge-like invariance and a reflection symmetry which means that both vector fields are photons. The gauge-like invariance implies that the fifth dimension is not directly observable; it also implies that charge is a constant of motion. The scalar field is analogous to the Brans-Dicke scalar field…

The transition of equation of state of effective dark energy in the DGP model with bulk contents

We investigate the effect of the bulk contents in the DGP braneworld on the evolution of the universe. We find that although the pure DGP model cannot accommodate the transition of the effective equation of state of dark energy, once the bulk matter T^5_5 is considered, the modified model can realize the w_{eff} crossing -1. However this transition of the equation of state cannot be realized by just considering bulk-brane energy exchange or the GB effect while the bulk matter contribution is not included. T^5_5 plays the major role in the modified DGP model to have the w crossing -1 behavior. …

超轻暗物质重组后磁生成中的数值反作用与有限时间能量转移

Numerical Backreaction and Finite-Time Energy Transfer in Post-Recombination Magnetogenesis from Ultralight Dark Matter

研究超轻暗物质驱动的重组后磁生成中规范场产生，追踪$\phi$模式与规范场模式耦合演化，数值工作证实分析结果，确定反作用关闭共振的情况及不同参数下能量转移到光子时的${\cal{F}}$情况。

The CP violation and scalar dark matter in a 331 model

The 331 model with right-handed neutrinos is re-assessed to investigate the CP violation in the quark sector. After the spontaneous symmetry breaking, the masses and physical fields of the particle content are obtained. The fermions content of the 331 model is enlarged to include exotic quarks with known electric charge and with masses defined at the TeV scale. The existence of these exotic quarks induces extra CP violations via couplings with quarks of the Standard Model mediated by charged gauge boson with mass fixed at the TeV scale. An extra discrete $\mathbb{Z}_{2}$ symmetry is introduced…

Towards nonlinear axion-dilaton electrodynamics: How can axionic dark matter mimic dilaton-photon interactions?

In the framework of the Einstein-Maxwell-axion-aether theory we establish the model, the Lagrangian of which contains the sin-type generalization of the term describing the axion-photon coupling, and the axionically induced cosine-type modification of the term attributed to the dilaton-photon interactions. The extension of the axion-dilaton-aether electrodynamics is inspired by the Jackson's idea concerning the internal symmetry of the equations of electromagnetism. The application of the extended theory to the anisotropic homogeneous cosmological model of the Bianchi-I type is considered. The…

Observing primordial magnetic fields through Dark Matter

Primordial magnetic fields are often thought to be the early Universe seeds that have bloomed into what we observe today as galactic and extra-galactic magnetic fields. Owing to their minuscule strength, primordial magnetic fields are very hard to detect in cosmological and astrophysical observations. We show how this changes if a part of neutral Dark Matter has a magnetic susceptibility. In this way, by studying Dark Matter one can obtain information about the properties of primordial magnetic fields, even if the latter have a comoving amplitude $B_0 \lesssim0.01~\mbox{nG}$. In our model Dark…

Field Theory with Fourth-order Differential Equations

We introduce a new class of higgs type complex-valued scalar fields $U$ with Feynman propagator $\sim 1/p^4$ and consider the matching to the traditional fields with propagator $\sim 1/p^2$ in the viewpoint of effective potentials at tree level. With some particular postulations on the convergence and the causality, there are a wealth of potential forms generated by the fields $U$, such as the linear, logarithmic, and Coulomb potentials, which might serve as sources of effects such as the confinement, dark energy, dark matter, electromagnetism and gravitation. Moreover, in some limit cases, we…

Cosmic Ferromagnetism of Magninos

We study the physical conditions for the occurrence of ferromagnetic instability in a neutral plasma of fermions. We consider a system of two species $M$ and $Y$ which are oppositely charged under a local $U(1)_{X}$, with $M$ much lighter than $Y$. The leading correction to free quasiparticle behaviour for the lighter species arises from the exchange interaction, while the heavier species remain spectators. This plasma, which is abelian, asymmetric and idealised, is shown to be naturally susceptible to the formation of a completely spin-imbalanced ferromagnetic state for the lighter species (d…