Decaying warm dark matter and neutrino masses

Neutrino masses may arise from spontaneous breaking of ungauged lepton number. Because of quantum gravity effects the associated Goldstone boson - the majoron - will pick up a mass. We determine the lifetime and mass required by cosmic microwave background observations so that the massive majoron provides the observed dark matter of the Universe. The majoron decaying dark matter scenario fits nicely in models where neutrino masses arise via the seesaw mechanism, and may lead to other possible cosmological implications.     

Monochromatic neutrino signals from dark matter annihilation

Dark matter (DM) annihilations in the Sun to neutrino–antineutrino pairs are known to have potentially observable signatures in neutrino telescopes such as IceCube and KM3. We propose a model independent analysis in which the monochomatic neutrino signal from dark matter (DM) annihilations in the Sun is related to the direct detection spin-independent and spin-dependent cross sections rather than assuming cross sections from a particular model. We propagate the neutrinos from the center of the Sun to the Earth taking into account matter effects on neutrino oscillations. For DM capture in the Sun via a large spin-dependent DM capture cross section the discovery prospects of the IceCube experiment are found to be promising.     

Scalar neutrino dark matter in the BLMSSM

The BLMSSM is an extension of the minimal supersymmetric standard model(MSSM).Its local gauge group is SU(3)_C×SU(2)_L×U(1)_Y×U(1)_B×U(1)_L.Supposing the lightest scalar neutrino is a dark matter candidate,we study the relic density and the spin independent cross section of sneutrino scattering off a nucleon.We calculate the numerical results in detail and find a suitable parameter space.The numerical discussion can confine the parameter space and provide a reference for dark matter research.     

Galactic Rotational velocities and dark neutrino matter

It has been assumed that neutrinos with non-vanishing rest mass contribute the gravitational field of our Galaxy. This contribution can be studied empirically from the orbiting velocities of galactic objects. In this way hints for the neutrino rest mass can be obtained from the rotation curve of our Galaxy.     

Minimal supergravity scalar neutrino dark matter and inverse seesaw neutrino masses

We show that within the inverse seesaw mechanism for generating neutrino masses, minimal supergravity naturally provides the scalar neutrino as the lightest superparticle. We also demonstrate that such schemes naturally reconcile the small neutrino masses with the correct relic scalar neutrino dark matter abundance and accessible direct detection rates in nuclear recoil experiments. This way, inverse seesaw minimal supergravity offers a common solution to the generation of the neutrino mass and to the origin of dark matter.     

Unifying inflation and dark matter with neutrino masses

We propose a simple model where a gauge-invariant inflaton is responsible for cosmic inflation and generates the seed for structure formation, while its relic thermal abundance explains the missing matter of the Universe in the form of cold dark matter. The inflaton self-coupling also explains the observed neutrino masses. All the virtues can be attained in a minimal extension of the standard model gauge group around the TeV scale. We can also unveil these properties of an inflaton in forthcoming space and ground based experiments.     

Testing a new sterile neutrino dark matter candidate

A new class of sterile neutrino dark matter is suggested by an explanation for time variations in the solar neutrino flux in which coupling of sterile neutrinos to other matter is via a very small flavor off-diagonal transition magnetic moment, TMM. The dark matter sterile neutrino’s decay in the radiative channel then depends on the local magnetic field and the unknown value of the TMM. An interesting application of this model uses the DAMA/LIBRA claimed detection of dark matter (assuming they are observing the electromagnetic signal) to provide the decay rate in the Earth’s field, and hence the TMM value. That version of the model is then examined to see if it can be falsified by cosmic X-ray observations or by other direct detection experiments. Particularly the latter could provide a simple, definitive test of this dark matter candidate, which would bring concordance to these experiments.     

Magnetic dipole moment and keV neutrino dark matter

We study magnetic dipole moments of right-handed neutrinos in a keV neutrino dark matter model. This model is a simple extension of the standard model with only right-handed neutrinos and a pair of charged particles added. One of the right-handed neutrinos is the candidate of dark matter with a keV mass. Some bounds on the dark matter magnetic dipole moment and model parameters are obtained from cosmological observations.     

Low-scale neutrino seesaw mechanism and scalar dark matter

Recently the AMS-02 experiment has released the data of positron fraction with a very small statistical error. Because of the small error, it is no longer easy to fit the data with single dark matter for a fixed diffusion model and dark matter profile. In this paper, we propose a new interpretation of the data: that it originates from decay of two-component dark matter. This interpretation gives a rough threshold of the lighter DM component. When DM decays into leptons, the positron fraction in the cosmic rays depends on the flavor of the final states, and this is fixed by imposing a non-Abelian discrete symmetry on our model. By assuming two gauge-singlet fermionic decaying DM particles, we show that a model with non-Abelian discrete flavor symmetry, e.g. $T_{13}$ , can give a much better fitting to the AMS-02 data compared with a single-component dark matter scenario. Few dimension-six operators of the universal leptonic decay of DM particles are allowed in our model, since its decay operators are constrained by the $T_{13}$ symmetry. We also show that the lepton masses and mixings are consistent with current experimental data, due to the flavor symmetry.     

Status of indirect dark matter search with neutrino telescopes

We discuss here the latest results of high energy neutrino experiments with neutrino telescopes in search for neutrino emissions from astrophysical sources where there is every likelihood that relic dark matter has been clumped and annihilates till presently, e.g. in the Sun, in the Galaxy Center and in the Dwarfs.     

Strong upper limits on sterile neutrino warm dark matter

Sterile neutrinos are attractive dark matter candidates. Their parameter space of mass and mixing angle has not yet been fully tested despite intensive efforts that exploit their gravitational clustering properties and radiative decays. We use the limits on gamma-ray line emission from the Galactic center region obtained with the SPI spectrometer on the INTEGRAL satellite to set new constraints, which improve on the earlier bounds on mixing by more than 2 orders of magnitude, and thus strongly restrict a wide and interesting range of models.     

Strategy for searching for a dark matter sterile neutrino

We propose a strategy for how to look for dark matter particles possessing a radiative decay channel and derive constraints on their parameters from observations of x rays from our own Galaxy and its dwarf satellites. When applied to sterile neutrinos in the keV mass range this approach gives a significant improvement to restrictions on neutrino parameters compared with previous works.     

Low-energy neutrino and dark matter physics with sub-keV germanium detectors

The TEXONO-CDEX Collaboration (Taiwan experiment on neutrino?CChina dark matter experiment) explores high-purity germanium (HPGe) detection technology to develop a sub-keV threshold detector for pursuing studies on low mass weakly interacting massive particles (WIMPs), properties of neutrino and the possibilities of neutrino-nucleus coherent scattering observation. This article will introduce the facilities of newly established China Jing-Ping Underground Laboratory (CJPL), preliminary result of cosmic ray background studies at CJPL, the dark matter studies pursued at Kuo-Sheng Neutrino Laboratory (KSNL) and research efforts to accomplish our physics goals.