Limits on new superweakly interacting particles from primordial nucleosynthesis

Keith A. Olive, David N. Schramm, Gary Steigman

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136 Scopus citations


The existence of massless (or low mass) weakly (or superweakly) interacting particles is predicted by various models of unified theories. Such particles (neutrinos, gravitinos, gravitons) would contribute to the early expansion rate of the universe and affect the outcome of primordial nucleosynthesis. We extend previous work on the limits to the number of "ordinary" neutrinos to more weakly interacting particles which decouple earlier in the evolution of the universe. We have evaluated the limits on the number of "new" particles permitted as a function of their interaction strength. Having been forced to consider the universe at earlier times and higher temperatures than was necessary in previous discussions we have dealt, qualitatively, with the transition from free quarks to confined hadrons. We find that the maximum number of superweakly interacting, light (< 1 MeV) particles is between ∼1 and ∼20, depending on the strength of their interaction. These constraints may serve as a useful guide for new unification theories.

Original languageEnglish (US)
Pages (from-to)497-515
Number of pages19
JournalNuclear Physics, Section B
Issue number3
StatePublished - May 25 1981

Bibliographical note

Funding Information:
work was supported by the Department of Energy (DE-AS02-

Funding Information:
We would like to thank M.A.B. Beg, C. Hill, J. Ellis, D. Kazanas,S . Margolis,D . NanopoulosR, .E. Shrock,R . Slansky,D . SutherlandM, . Turner,R .V. WagonerS, . Weinberga nd P. Wiita for valuabled iscussionsA. t the Universityo f Chicagothis work was supportedin part by NSF grantsA ST 76-21707a nd AST 78-20402a nd (KO's) Fannie and John Hertz FoundationF ellowship.A t the Bartol Research

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