paper

New Constraints on Radiative Decay of Long-Lived Particles in Big Bang Nucleosynthesis with New He Photodisintegration Data

arXiv:0806.4040 · doi:10.1103/PhysRevD.79.123513

Abstract

A recent measurement of He photodisintegration reactions, He(,)H and He(,)He with laser-Compton photons shows smaller cross sections than those estimated by other previous experiments at MeV. We study big-bang nucleosynthesis with the radiative particle decay using the new photodisintegration cross sections of He as well as previous data. The sensitivity of the yields of all light elements D, T, He, He, Li, Li and Be to the cross sections is investigated. The change of the cross sections has an influence on the non-thermal yields of D, He and He. On the other hand, the non-thermal Li production is not sensitive to the change of the cross sections at this low energy, since the non-thermal secondary synthesis of Li needs energetic photons of MeV. The non-thermal nucleosynthesis triggered by the radiative particle decay is one of candidates of the production mechanism of Li observed in metal-poor halo stars (MPHSs). In the parameter region of the radiative particle lifetime and the emitted photon energy which satisfies the Li production above the abundance level observed in MPHSs, the change of the photodisintegration cross sections at MeV as measured in the recent experiment leads to % reduction of resulting He abundance, whereas the Li abundance does not change for this change of the cross sections of He(,)H and He(,)He. The Li abundance, however, could show a sizable change and therefore the future precise measurement of the cross sections at high energy 50 MeV is highly required.

10 pages, 7 figures, conclusion not changed, to be published in PRD

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