Nuclear physics and cosmology

Schramm, David N.

Nuclear physics has provided one of two critical observational tests of all Big Bang cosmology, namely Big Bang Nucleosynthesis. Furthermore, this same nuclear physics input enables a prediction to be made about one of the most fundamental physics questions of all, the number of elementary particle families. The standard Big Bang Nucleosynthesis arguments are reviewed. The primordial He abundance is inferred from He-C and He-N and He-O correlations. The strengthened Li constraint as well as D-2 plus He-3 are used to limit the baryon density. This limit is the key argument behind the need for non-baryonic dark matter. The allowed number of neutrino families, N(nu), is delineated using the new neutron lifetime value of tau(n) = 890 + or - 4s (tau(1/2) = 10.3 min). The formal statistical result is N(nu) = 2.6 + or - 0.3 (1 sigma), providing a reasonable fit (1.3 sigma) to three families but making a fourth light (m(nu) less than or equal to 10 MeV) neutrino family exceedly unlikely (approx. greater than 4.7 sigma). It is also shown that uncertainties induced by postulating a first-order quark-baryon phase transition do not seriously affect the conclusions.

Document ID

19900004851

Acquisition Source

Legacy CDMS

Document Type

Conference Paper

Authors

Date Acquired

September 6, 2013

Publication Date

December 1, 1989

Subject Category

Report/Patent Number

Meeting Information

Meeting: International Nuclear Physics Conference

Location: Sao Paulo

Country: Brazil

Start Date: August 20, 1989

End Date: August 26, 1989

Accession Number

90N14167

Funding Number(s)

Distribution Limits

Public

Work of the US Gov. Public Use Permitted.

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