相关论文: Is gravitino still a warm dark matter candidate?
One of the possible explanations for the dark matter needed in the standard cosmological model is so-called warm dark matter, in the form of right-handed ("sterile") neutrinos with a mass in the keV range. I describe how various properties…
The thermal history of the universe before the epoch of nucleosynthesis is unknown. The maximum temperature in the radiation-dominated era, which we will refer to as the reheat temperature, may have been as low as 0.7 MeV. In this paper we…
The axino is the fermionic superpartner of the axion. Assuming the axino is the lightest supersymmetric particle and stable due to R-parity conservation, we compute the relic axino density from thermal reactions in the early Universe. From…
We review the main proposals of particle physics for the composition of the cold dark matter in the universe. Strong axion contribution to cold dark matter is not favored if the Peccei-Quinn field emerges with non-zero value at the end of…
The latest experimental results from the LHC and dark matter (DM) searches suggest that the parameter space allowed in supersymmetric theories is subject to strong reductions. These bounds are especially constraining for scenarios entailing…
In recent work, it has been argued that multi-TeV masses for scalar superpartners are not unnatural. Indeed, they appear to have significant phenomenological virtues. Here we explore the implications of such `focus point' supersymmetry for…
Cosmological issues are examined when gravitino is the lightest superparticle (LSP) and R-parity is broken. Decays of the next lightest superparticles occur rapidly via R-parity violating interaction, and thus they do not upset the big-bang…
Supersymmetry offers a cold dark matter candidate, provided that lepton number is {\em not violated by an odd number of units}. On the other hand, lepton number violation by even (two) units gives us an attractive mechanism of neutrino mass…
We investigate the effects of non-thermally produced dark matter on large-scale structure formation, focusing on the gravitino dark matter. Our analysis shows that large-scale structure measurements from the SDSS LRG data offer a promising…
We revisit MSSM scenarios with light neutralino as a dark matter candidate in view of the latest LHC and dark matter direct and indirect detection experiments. We show that scenarios with a very light neutralino (~ 10 GeV) and a scalar…
We show that a neutral scalar field, \sigma, of two Higgs doublet extensions of the Standard Model incorporating the seesaw mechanism for neutrino masses can be identified as a consistent {\it warm} dark matter candidate with a mass of…
We show that if dark matter in a typical galaxy is a degenerate Fermi gas, particles should have a mass of $\sim$ 1eV for the galaxy to be stable. While this is the mass range of the active neutrinos, they are not a dark matter candidate in…
It has been suggested that a sterile neutrino \nu_s which mixes with standard neutrinos can form nonthermal ``cool'' Dark Matter if its mass and mixing angle fall in the ranges 0.1 keV \lsim m_s \lsim 10 keV and 10^{-10} \lsim \sin^2 \theta…
Among various supersymmetric (SUSY) models, gauge-mediated SUSY breaking models with an ultra-light gravitino of mass m_{3/2} \lesssim O(10) eV are very attractive, since they are completely free from notorious gravitino problems. A…
A new modified string-inspired modular invariant supergravity model is proposed and is applied to realize the slow roll inflation in Einstein frame, so that the model explains WMAP observations very well. Gravitino mass and their production…
We investigate supergravity models in which the lightest supersymmetric particle (LSP) is a stable gravitino. We assume that the next-lightest supersymmetric particle (NLSP) freezes out with its thermal relic density before decaying to the…
It has been shown that very light or even massless neutralinos are consistent with all current experiments, given non-universal gaugino masses. Furthermore, a very light neutralino is consistent with astrophysical bounds from supernov{\ae}…
Gravitinos are expected to be produced in any local supersymmetric model. Using their abundance prediction as a function of the reheating energy scale, it is argued that the next generation of Cosmic Microwave Background experiments could…
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…
Gravitinos and axinos produced in the late decays of other supersymmetric particles are well-motivated dark matter (DM) candidates, whose experimental evidences are very distinctive and different from other standard candidates, as thermal…