Related papers: Axionic Hot Dark Matter in the Hadronic Axion Wind…
Axions provide a natural and well-motivated dark matter candidate, with the capability to convert directly to photons in the presence of an electromagnetic field. A particularly compelling observational target is the conversion of dark…
We have recently proposed a new candidate for baryonic dark matter: very cold molecular gas, in near-isothermal equilibrium with the cosmic background radiation at 2.73 K. The cold gas, of quasi-primordial abundances, is condensed in a…
Dark matter could be a thermal relic comprised of strongly interacting massive particles (SIMPs), where $3 \rightarrow 2$ interactions set the relic abundance. Such interactions generically arise in theories of chiral symmetry breaking via…
Dark (hidden) photons are widely recognised as well motivated candidates for physics beyond the standard model, and have been invoked for the solution of several outstanding problems, including to account for the dark matter in the…
Axions are a well-motivated dark matter candidate, with a host of experiments around the world searching for direct evidence of their existence. The ORGAN Experiment is a type of axion detector known as an axion haloscope, which takes the…
While most searches for cosmic axions so far focused on their cold relics as (a component of) dark matter, various well-motivated cosmological sources can produce "boosted" axions that remain relativistic today. We demonstrate that…
Mixed dark matter models with one low-mass (e.g. 2.4eV) neutrino flavor are shown to be in good agreement with observations if the neutrinos have non-zero chemical potentials. This agreement holds (except for the problem with a low-age…
We present models that can reconcile the solar and atmospheric neutrino data with the existence of a hot dark matter component in the universe. This dark matter is a quasi-Dirac neutrino whose mass $m_{DM}$ arises at the one-loop level. The…
The subjects of this thesis are the invisible axion and the more general family of axion-like particles. The invisible axion is a hypothetical elementary particle and a cold dark matter candidate. I present an improved computation of the…
An ultralight scalar boson with mass $m_1 \simeq 10^{-22}$ eV is gaining credence as a Dark Matter (DM) candidate that explains the dark cores of dwarf galaxies as soliton waves. Such a boson is naturally interpreted as an axion generic in…
In this paper, we revisit the experimental constraints on the multipolar dark matter that has derivative coupling to the visible sector mediated by the Standard Model photon. The momentum dependent interaction enables them to be captured…
Current observations of the cosmic microwave background could confirm an increase in the radiation energy density after primordial nucleosynthesis but before photon decoupling. We show that, if the gravitino problem is solved by a light…
Axions are a theoretically promising dark matter (DM) candidate. In the presence of radiation from bright astrophysical sources at radio frequencies, nonrelativistic DM axions can undergo stimulated decay to two nearly back-to-back photons,…
The lensing data of the galaxy cluster Abell 1689 can be explained by an isothermal fermion model with a mass of 1-2 eV. The best candidate is the 1.5 eV neutrino; its mass will be searched down to 0.2 eV in KATRIN 2015. If its righthanded…
Ultralight axion or axionlike particles are one of the most promising candidates for dark matter because they are a well-motivated solution for the theoretical strong $CP$ problem and observational issues on small scales, i.e. the core-cusp…
Axions, hypothetical particles proposed to solve the strong CP problem and considered promising dark matter candidates, can be produced in the Sun and interact in detectors via couplings to photons, electrons, or nucleons. The CUORE and…
We point out that if the Peccei-Quinn symmetry breaking scale $F_a$ is in a range of the hadronic axion window ($F_a\sim 10^6$GeV), the ee$\gamma\gamma+/\!\!\!\! E_T$ event in the CDF experiment can be naturally explained by a no-scale…
We review the status of axino dark matter. Two hierarchy problems, the strong CP problem and the gauge hierarchy problem, have led to introducing into particle physics a spontaneously broken global Peccei-Quinn symmetry and a softly broken…
We introduce a new experimental method for solar hadronic axions search. It is suggested that these axions are created in the Sun during M1 transition between the first thermally excited level at 9.4 keV and the ground state in $^{83}Kr$.…
Four decades after its prediction, the axion remains the most compelling solution to the Strong-CP problem and a well-motivated dark matter candidate, inspiring a host of elegant and ultrasensitive experiments based on axion-photon mixing.…