Xiangdong Shi

New Dark Matter Candidate: Nonthermal Sterile Neutrinos

We propose a new and unique dark matter candidate:

LEPTONIC DOMAINS IN THE EARLY UNIVERSE AND THEIR IMPLICATIONS

\sim 100

Neutrinos and Supermassive Stars: Prospects for Neutrino Emission and Detection

eV to

Neutrino mixing generated lepton asymmetry and the primordial He-4 abundance

\sim 10

Big bang nucleosynthesis and active sterile neutrino mixing: Evidence for maximal mu-neutrino tau-neutrino mixing in Super-Kamiokande?

keV sterile neutrinos produced via lepton number-driven resonant MSW (Mikheyev-Smirnov-Wolfenstein) conversion of active neutrinos. The requisite lepton number asymmetries in any of the active neutrino flavors range from 10

OBSERVING THE BIRTH OF SUPERMASSIVE BLACK HOLES WITH THE PLANNED ICECUBE NEUTRINO DETECTOR

^{-3}

Peculiar Hubble Flows in Our Local Universe

to 10

Neutrino Production of Deuterium in Supermassive Stars and Possible Implications for Deuterium Detections in Lyman-Limit Systems

^{-1}

Increase in the primordial4Heyield in the two-doublet four-neutrino mixing scheme

of the photon number - well within primordial nucleosynthesis bounds. The unique feature here is that the adiabaticity condition of the resonance strongly favors the production of lower energy sterile neutrinos. The resulting non-thermal (cold) energy spectrum can cause these sterile neutrinos to revert to non-relativistic kinematics at an early epoch, so that free-streaming lengths at or below the dwarf galaxy scale are possible. Therefore, the main problem associated with light neutrino dark matter candidates can be circumvented in our model.

Supermassive Objects as Gamma-Ray Bursters

Author(s): Shi, X; Fuller, GM | Abstract: We apply causality considerations to active-sterile neutrino transformation-based schemes for lepton number generation in the early Universe. These considerations necessarily lead to the creation of spatial domains of lepton number with opposite signs. Lepton number gradients at domain boundaries can open a new channel for Mikheyev-Smirnov-Wolfenstein resonant production of sterile neutrinos (νs). This enhanced νs production allows considerable tightening of big bang nucleosynthesis constraints on active-sterile neutrino mixing. 1999