相关论文: Axion-Dilaton Destabilization and the Hubble Tensi…

The recently sharpened H_0 tension is argued not to be a result of data calibration or other systematic but an indication for the common nature of dark matter and dark energy. This conclusion is devised within modified weak-field General…

The current cosmological constraints on a dark matter axion are reviewed. We describe the basic mechanisms by which axions are created in the early universe, both in the standard thermal scenario in which axion strings form and in…

We propose an infrared mechanism for alleviating the Hubble constant tension, based on a small departure from entanglement equilibrium at the cosmological apparent horizon. If the horizon entanglement entropy falls slightly below the…

We develop a modified interacting dark energy (IDE) model to study the redshift evolution of the Hubble constant ($H_0$), in light of the Hubble tension. In this framework, the energy exchange between dark energy and dark matter induces a…

We develop a new phenomenological model that addresses current tensions between observations of the early and late Universe. Our scenario features: (i) a decaying dark energy fluid (DDE), which undergoes a transition at $z \sim 5,000$, to…

In this talk, I review briefly a scenario for the evolution of a string-inspired cosmological model, in which condensates of primordial gravitational waves (GW), formed at the very early eras after the Big Bang, are considered responsible…

Astrophysical tests of the stability of fundamental couplings, such as the fine-structure constant $\alpha$, are becoming an increasingly powerful probe of new physics. Here we discuss how these measurements, combined with local atomic…

In most models of dark energy the structure formation stops when the accelerated expansion begins. In contrast, we show that the coupling of dark energy to dark matter may induce the growth of perturbations even in the accelerated regime.…

The axion electromagnetic anomaly induces an oscillating electric dipole for {\em any} static magnetic dipole. Static electric dipoles do not produce oscillating magnetic moments. This is a low energy theorem which is a consequence of the…

The discrepancy in measurements of the Hubble constant indicates new physics in dark energy, dark matter, or both. Drawing inspiration from string theory, we explore possible solutions to overcome the $H_0$ problem. We investigate the…

Early dark energy is a promising potential resolution of the Hubble tension. Unfortunately, many models suffer from the need to fine-tune their initial conditions to ensure that the epoch of early dark energy coincides with matter-radiation…

Early dark energy (EDE) that behaves like a cosmological constant at early times (redshifts $z\gtrsim3000$) and then dilutes away like radiation or faster at later times can solve the Hubble tension. In these models, the sound horizon at…

We calculate dilaton and axion radiation generated in the collision of two straight initially unexcited strings and give a rough cosmological estimate of dilaton and axion densities produced via this mechanism in the early universe.

It is found that the evolutions of density perturbations on the super-Hubble scales are unstable in the model with dark-sector interaction $Q$ proportional to the energy density of cold dark matter (CDM) $\rho_m$ and constant equation of…

We investigate time-dependent spherically symmetric solutions of the four-dimensional Einstein-Maxwell-axion-dilaton system, with the dilaton coupling that occurs in low-energy effective heterotic string theory. A class of…

The emergence of an increasingly strong tension between the Hubble rate inferred from early- and late-time observations has reinvigorated interest in nonstandard scenarios, with the aim of reconciling these measurements. One such model…

The origin of dark matter in the universe may be weakly interacting scalar particles produced by amplification of quantum fluctuations during a period of dilaton-driven inflation. We present two interesting cases, the case of small…

Coupled dark sector models have gained significant attention, motivated by recent advances in cosmology and the pressing need to address unresolved puzzles. In this work, we study coupled scalar dark sector models inspired by…

Oscillating scalar field condensates induce small amplitude oscillations of the Hubble parameter which can induce a decay of the condensate due to a parametric resonance instability [1]. We show that this instability can lead to the decay…

Using a single dilaton field, a unified model of the Universe is proposed, which evolves from the radiation-like dominance in the Big Bang, to the dark-matter-like dominance in the early Universe, to the coexistence of both dark-matter-like…