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Parker, Ronald J. D.
The effects of cold dark matter on big bang nucleosynthesis.

Order No. 8918486

We show that the annihilation of cold, weakly-interacting dark matter candidates (chi) subsequent to chi chi freeze-out can significantly affect the primordial abundance of light elements. The largest effects are (1) between the n/p freeze-out temperature (T = 0.7 MeV) and the onset of nucleosynthesis at T = 0.1 MeV, chi chi annihilations increase the n/p ratio, leading to increased 4He production; (2) following 4He synthesis, baryonic products n, n(bar), p of chi chi annihilations dissociate some the the 4He into D and 3He, leading to increased D + 3He abundances; (3) toward the end of nucleosynthesis, neutrons from chi chi annihilation lead to n + 7Be to become p + 7Li, resulting in increased 7Li + 7Be production for low values of eta = n (sub)b / n (sub)gamma and decreased 7Li + 7Be production for large eta, and (4) long after nucleosynthesis, once the universe cools below T = 1 keV, the electromagnetic shower produced by electrons, positrons and photons from residual chi chi annihilations cause further dissociation of 4He, leading to increased D + 3He abundances. The most important result is that for Direc and Majorna neutrinos, the 7Li constraints on eta from SBBN are noticeably affected, with larger values of eta being favored.

A summary of scattering rates for processes in the electromagnetic shower, containing corrections to numerous misprints in other sources, is presented in an Appendix. A listing of FORTRAN code used in the shower calculation is also included. Finally, the results are discussed in the light of Maharishi's Vedic Science, an ancient science which presents both knowledge and experience of the transcendental basis of life. Source: DAI, 50, no. 05B, (1989): 1987

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