Glenn D. Starkman

Limits on late decaying particles from nucleosynthesis

Late decaying (τ > 104 s) particles can alter the standard big bang predictions for the light-element abundances. If M > 10 GeV, light-element production and 4He destruction can take place when hadronic decay products interact with the ambient protons and 4He causing hadronic showers; pepletion is the result of photodissociation by energetic decay protons. Previous works [1–4] which put limits in the properties of these particles ignored hadronic showers entirely, and usually considered only selected photodissociation reactions. We consider the full set of reactions and present both analytic and numerical bounds on the properties of particles with lifetimes greater than 104 s. This drastically alters the limits on particle masses, lifetimes and abundances. For a gravitino lighter than a TeV, the reheat temperature must be less than 1010 GeV.

Atomic enhancements in the detection of weakly interacting particles

Abstract Proposed holometric and supercolloidal detectors can measure energy depositions of the order of atomic energies. At these energies, atomic bound state effects lead to great enhancements in the detection of weakly interacting particles. As an example, we show that solar axions could give event rates 10 5 –10 6 times larger than published neutrino detector design capabilities. Thus, relatively small detectors might see solar axions.

Axiorecombination: A New Mechanism for Stellar Axion Production

Abstract Axiorecombination, e− + Z → (e−, Z) + a, is considered as a source of light pseudoscalar axions in stars. This process dominates the energy loss in axions for low-mass main-sequence stars, M ⪅ 0.2M ⊚ . For the sun, axiorecombination accounts for ∼ 1 4 of total axion flux at energies above ∼2 keV.

A detector for the cosmic neutrino background

Abstract A detection scheme for the cosmic neutrino background, based on bremsstrahlung in its coherent scattering off free cold electrons, is explored. Both magnetic moment and weak interaction couplings are considered for arbitrary Dirac neutrino masses. Photon production rates may reach values of ∼ 10 8 ( μ ν /10 −10 μ B ) 2 /day for neutrinos with a magnetic moment μ ν , and values of ∼ 10 −3 /day for weakly-interacting Dirac neutrinos with a mass of 25 eV; per 1 kton of a solid with mostly free electrons.

Ultralow Background Searches for ββ -Decay, Cold Dark Matter and Solar Axions

An ultralow background Ge detector in the Homestake gold mine is applied to searches for Oν ββ-decay, cold dark matter candidates and invisible axions from the sun. A large body of low background Ge data imply ≲ 2.3 eV. Particles with spin independent Z° exchange interactions and masses between 20 GeV and 5 TeV are excluded as dominant in the galactic halo. Finally, axions with F/2x′e ≲ 0.5 × 107 GeV are also ruled out.