Conveners
Parallel Session Thursday Cosmo: Cosmology III
- Hyungjin Kim (T (Cosmology))
Parallel Session Thursday Cosmo: Cosmology IV
- Gilly Elor
The dark photon (DP) is a simple and well-motivated candidate for BSM physics. For keV masses or lighter, the sun can potentially produce a large flux of these particles which can be searched for by so-called helioscopes. In this talk, I will discuss the impact of the angular and spectral distribution of solar DPs on these searches. Considering calibration images of the HINODE XRT solar x-ray...
Cosmological relaxation of the electroweak scale provides an elegant solution to the Higgs mass hierarchy problem. In the simplest model, the Higgs mass is scanned during inflation by another scalar field, the relaxion, whose slow-roll dynamics selects a naturally small Higgs vev. In this work we investigate the mechanism in a less conventional regime where the relaxion is subject to large...
Axion as a non-thermal dark matter could significantly change its cosmological evolution by interacting with a thermalized hidden sector. We study pure hidden Yang-Mills (YM) gauge fields as an example. The hidden YM gauge fields effectively act as friction to the axion field, and it results in the significant dilution of the axion abundance. We present an analytical and numerical...
In the presence of a feebly-interacting light particle, its signal might leave an imprint on astrophysical observations so one could obtain meaningful constraints on a parametric space. In this talk, I will discuss additional light gauge boson (so called dark gauge boson) cooling of neutron stars and its implications. With the rigorous treatment of the effective field theory prescription and...
Electromagnetism in curved space time predicts induced magnetic fields arising from gravitational waves (GWs) in the presence of external electric and magnetic fields. Using this fact, it has been suggested to use axion detectors and reinterpret their results to observe high-frequency GWs (above 100 kHz). In this work, we enlarge this novel possibility by considering more general detector...
In the last few years, the paradigm of axion kinetic misalignment has attracted attention as a way to account for axion dark matter in the experimentally accessible low$-f_a$ regime. Kinetic misalignment goes beyond the standard misalignment mechanism by assuming that the axion inherits an initial non-zero velocity from early dynamics, which enhances the dark matter relic relative to the...
A massive astrophysical object deforms the local distribution of dark matter, resulting in a local overdensity of dark matter. This phenomenon is often referred to as gravitational focusing. In the solar system, the gravitational focusing due to the Sun induces modulations of dark matter signals on terrestrial experiments. We consider the gravitational focusing of light bosonic dark matter...
A leading effort to detect axion dark matter is through its influence on nuclear spins. The
detection scheme involves polarizing a sample of nuclei within a strong static magnetic field and
searching for spin-precession induced by the oscillating axion field. We revisit the signal and noise
in these experiments, finding some key differences with the existing literature. Most...
We propose a novel mechanism to generate sterile neutrinos $\nu_s$ in the early Universe, by converting ordinary neutrinos $\nu_\alpha$ in scattering processes $\nu_s\nu_\alpha\to\nu_s\nu_s$. After initial production by oscillations, this leads to an exponential growth in the $\nu_s$ abundance. We show that such a production regime naturally occurs for self-interacting $\nu_s$, and that this...
We consider a $U(1)_D$ extension of the Standard Model that accounts for the neutrino masses and study in detail dark matter phenomenology. The model under consideration includes a vector WIMP and a fermion FIMP dark matter candidates and thus gives rise to two-component dark matter scenarios. We discuss different regimes and mechanisms of production and the interplay between neutrino masses...
A model involving quantum gravitationally induced decoherence is proposed to investigate on the properties of fermionic dark matter using astrophysical neutrinos.
The main assumption of the model is that interactions of particles with the spacetime foam violate global quantum numbers such as lepton number and only conserve unbroken gauge quantum numbers.
Hence, if $N$ hypothetical...
In the Standard Model a Dark Matter candidate is missing, but it is relatively
simple to enlarge the model including one or more suitable particles.
We consider in this paper one such extension, inspired by simplicity and
by the goal to solve more than just the Dark Matter issue.
Indeed we consider a local $U(1) $ extension of the SM providing an
axion particle to solve the strong CP...
A non-minimal dark sector could explain why WIMP dark matter has evaded detection so far. Based on the extensively studied example of a simplified t-channel dark matter model involving a colored mediator, we demonstrate that the Sommerfeld effect and bound state formation must be considered for an accurate prediction of the relic density and thus also when inferring the experimental...
Spinning black holes (BHs) can efficiently transfer energy to the surrounding environment via superradiance. In particular, when the Compton length of a particle is comparable to the gravitational radius of a BH, the particle's occupation number can be exponentially amplified. In this talk, I will discuss the effect of the primordial-black-hole (PBH) superradiant instabilities on the...
In this talk, I will discuss the impact of non-galactic dark matter particles in direct detection searches. Firstly, I will emphasize its relevance when the dark matter is light, and scatters elastically off a nucleus or an electron. Secondly, I will discuss the importance of the non-galactic flux when the dark matter scatters inelastically off a nucleus or an electron. For light dark matter,...
Primordial black holes (PBHs) form via gravitational collapse of large density perturbations during the radiation-dominated epoch. If a PBH have a mass smaller than O(10^9)g, it can completely evaporate before the Big Bang nucleosynthesis (BBN). We consider the case where PBHs once dominate the Universe and realize reheating through Hawking radiation. The thermalization of the high energy...
