相关论文: $\mathbf{{N}_{eff}}$ from Excited DM state
Neutrinos are often considered as a portal to new physics beyond the Standard Model (SM) and might possess phenomenologically interesting interactions with dark matter (DM). This paper examines the cosmological imprints of DM that interacts…
Light, weakly-coupled dark sectors may be naturally decoupled in the early universe and enter equilibrium with the Standard Model bath during the epoch of primordial nucleosynthesis. The equilibration and eventual decoupling of dark sector…
The possibility for the excited nuclear states to decay by emission of the neutrino-antineutrino pair in direct competition with electromagnetic decay modes is commented upon.
We study the effect of the early kinetic decoupling in a model of fermionic dark matter (DM) that interacts with the standard model particles only by exchanging the Higgs boson. There are two DM-Higgs couplings, namely CP-conserving and…
We consider relatively heavy neutrinos $\nu_H$, mostly contributing to a sterile state $\nu_s$, with mass in the range 10 MeV $\lesssim m_s \lesssim m_{\pi} \sim 135$ MeV, which are thermally produced in the early universe in collisional…
We discuss a simple extension of the Standard Model (SM) that provides an explicit realization of the dark-matter (DM) neutrino-portal paradigm. The dark sector is composed of a scalar $ \Phi $ and a Dirac fermion $ \Psi $, with the latter…
The recent WMAP and Planck data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Many extensions of the standard model provide dark matter candidates, in…
We point out a correlation between the effective number of relativistic degrees of species $\Delta N_\text{eff}$, the cosmologically measured $m_{\nu,\text{sterile}}^{\text{eff}}$, and the terrestrially measured neutrino mass sum and…
In this work we give a comprehensive analysis on the phenomenology of a specific $\mathbb{Z}_3$ dark matter (DM) model in which neutrino mass is induced at two loops by interactions with a DM particle that can be a complex scalar or a Dirac…
Elastic scattering between dark matter particles and a relativistic species such as photons or neutrinos leads to a transfer of energy from the latter due to their intrinsically different temperature scaling relations. In this work, we…
Thermal dark matter that couples more strongly to electrons and photons than to neutrinos will heat the electron-photon plasma relative to the neutrino background if it becomes nonrelativistic after the neutrinos decouple from the thermal…
Cosmological observations are becoming increasingly sensitive to the effects of light particles in the form of dark radiation (DR) at the time of recombination. The conventional observable of effective neutrino number, $N_{\rm eff}$, is…
The scotogenic model provides a minimal and elegant framework that simultaneously explains neutrino masses and accommodates a viable dark matter (DM) candidate. In this work, we investigate the phenomenology of fermionic DM in the…
We explore the impact of highly excited bound states on the evolution of number densities of new physics particles, specifically dark matter, in the early Universe. Focusing on dipole transitions within perturbative, unbroken gauge…
In the presence of interactions between neutrinos and dark matter (DM), DM can potentially be produced via freeze-in from the neutrino sector. We investigate the implications of such a scenario for the evolution of both DM and neutrinos in…
If dark matter (DM) carries anti-baryon number, a DM particle may annihilate with a nucleon by flipping to anti-DM. Inspired by Hylogenesis models, we introduce a single component DM model where DM is asymmetric and carries B and L as -1/2.…
We study the possibility of probing the radiative Dirac seesaw model with dark sector particles going inside the loop, popularly referred to as the Dirac scotogenic model via measurements of effective relativistic degrees of freedom ${\rm…
We study dark matter (DM) models in which there are two dark sector particles, $\chi_1$ and $\chi_2$, of near mass. In such models, co-annihilation of $\chi_1$ and $\chi_2$ may be the dominant process controlling the DM relic density during…
We discuss Dirac neutrinos whose right-handed component $\nu_R$ has new interactions that may lead to a measurable contribution to the effective number of relativistic neutrino species $N_{\rm eff}$. We aim at a model-independent and…
In this paper, we introduce a novel program of fixed-target searches for thermal-origin Dark Matter (DM), which couples inelastically to the Standard Model. Since the DM only interacts by transitioning to a heavier state, freeze-out…