Naoya Hata

Big Bang nucleosynthesis in crisis

A new evaluation of the constraint on the number of light neutrino species ({ital N}{sub {nu}}) from big bang nucleosynthesis suggests a discrepancy between the predicted light element abundances and those inferred from observations, unless the inferred primordial {sup 4}He abundance has been underestimated by 0.014{plus_minus}0.004 (1{sigma}) or less than 10% (95% C.L.) of {sup 3}He survives stellar processing. With the quoted systematic errors in the observed abundances and a conservative chemical evolution parametrization, the best fit to the combined data is {ital N}{sub {nu}}=2.1{plus_minus}0.3 (1{sigma}) and the upper limit is {ital N}{sub {nu}}{lt}2.6 (95% C.L.). The data are inconsistent with the standard model ({ital N}{sub {nu}}=3) at the 98.6% C.L. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

Astrophysical solutions are incompatible with the solar neutrino data.

We consider the most general solar model, using the neutrino fluxes as free parameters constrained only by the solar luminosity, and show that the combined solar neutrino data exclude any astrophysical solution at 97% C.L. Our best fit to the

Solar model uncertainties, MSW analysis, and future solar neutrino experiments.

^{7}\mathrm{Be}

Cosmological implications of two conflicting deuterium abundances

and

Implications of combined solar neutrino observations and their theoretical uncertainties

^{8}\mathrm{B}

Predicting big bang deuterium

fluxes is, respectively, 8% and 37\ifmmode\pm\else\textpm\fi{}4% of the standard solar model prediction, but only with a large

Implications of the GALLEX source experiment for the solar neutrino problem

{\ensuremath{\chi}}^{2}

Model-independent determination of the solar neutrino spectrum with and without the MSW effect.

(4.8 for 1 DF). This best fit to the fluxes contradicts explicit nonstandard solar models, which generally reduce the

Earth effect in the MSW analysis of the solar neutrino experiments

^{8}\mathrm{B}

Theoretical implications of the combined solar neutrino observations

flux more than the