Related papers: Decaying Neutrinos and Large Scale Structure Forma…
As electromagnetic showers may alter the abundance of Helium, Lithium, and Deuterium, we can place severe constraints on the lifetime and amount of electromagnetic energy injected by long-lived particles. Considering up-to-date measurements…
We propose a model to explain tiny masses of neutrinos with the lepton number conservation, where neither too heavy particles beyond the TeV-scale nor tiny coupling constants are required. Assignments of conserving lepton numbers to new…
We calculate predictions from wide class of `active' models of cosmic structure formation which allows us to scan the space of possible defect models. We calculate the linear cold dark matter power spectrum and Cosmic Microwave Background…
We explore the cosmological consequences of kinetically mixed dark photons with a mass between 1 MeV and 10 GeV, and an effective electromagnetic fine structure constant as small as $10^{-38}$. We calculate the freeze-in abundance of these…
We propose a model where neutrino masses are generated at three loop order but neutrinoless double beta decay occurs at one loop. Thus we can have large neutrinoless double beta decay observable in the future experiments even when the…
Dark energy as a quintessence component causes a typical modification of the background cosmic expansion, which in addition to its clustering properties, can leave a potentially distinctive signature on large scale structures. Many previous…
Measurements of the evolution with redshift of the number density of massive galaxy clusters are used to constrain the energy density of massive neutrinos and so the sum of neutrino masses $\sum m_\nu$. We consider a spatially-flat…
Neutrino mass generation may affect the basic structure of the electroweak symmetry breaking sector. We consider a broad class of elementary particle theories where neutrinos get mass at a low mass scale. We show how these can be made…
From data recently reported from the IceCube telescope, we derive new bounds on the monochromatic neutrino signal produced from dark matter particle decays. In the few TeV to tens of TeV energy range, these bounds turn out to be better than…
We investigate whether cosmological data suggest the need for massive neutrinos. We employ galaxy power spectrum measurements from the Sloan Digital Sky Survey (SDSS) and the Two Degree Field Galaxy Redshift Survey (2dFGRS), along with…
Cosmic background neutrinos have a large velocity dispersion, which causes the evolution of long-wavelength density perturbations to depend on scale. This scale-dependent growth leads to the well-known suppression in the linear theory…
We calculate the linear power spectrum for a range of mixed dark matter (MDM) models assuming a massive (few eV) boson, $\phi$, instead of a neutrino as the hot component. We consider both the case where the hot dark matter (HDM) particle…
We review the recent proposal by Lattanzi & Valle of the majoron as a suitable warm dark matter candidate. The majoron is the Goldstone boson associated to the spontaneous breaking of ungauged lepton number, one of the mechanisms proposed…
Within the framework of the Standard Model of particle physics and standard cosmology, observations of the Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAO) set stringent bounds on the sum of the masses of neutrinos.…
We analyse the formation of cosmic structures in models where the dark matter is dominated by light gravitinos with mass of $ 100$ eV -- 1 keV, as predicted by gauge-mediated supersymmetry (SUSY) breaking models. After evaluating the number…
The late-time entropy production by the massive particle decay induces the various cosmological effects in the early epoch and modify the standard scenario. We investigate the thermalization process of the neutrinos after the entropy…
We stress that massive neutrinos may be Majorana particles even if the effective mass of the neutrinoless double beta decay m_ee vanishes. We show that current neutrino oscillation data do allow m_ee = 0 to hold, if the Majorana…
We briefly review the recent results of constraining neutrino mass in dynamical dark energy models using cosmological observations and summarize the findings. (i) In dynamical dark energy models, compared to $\Lambda$CDM, the upper limit of…
We study the effect of the MeV-scale asymmetric dark matter annihilation on the effective number of neutrinos $N_{\rm eff}$ at the epoch of the big bang nucleosynthesis. If the asymmetric dark matter $\chi$ couples more strongly to the…
We investigate decays of hypothetical unstable new physics particles into metastable species such as muons, pions, or kaons in the Early Universe, when temperatures are in the MeV range, and study how they affect cosmic neutrinos. We…