New neutrino physics?  Solar Neutrinos  Solar Neutrinos

The solar neutrino problem

The solar neutrino problem had origin from the discrepancy between the expectations of the solar $\nu_e$ flux, as calculated by the Solar Standard Model, and the experimental results.

But even if we forget the Solar Model and we study the compatibility among the available experimental data we find an internal inconsistency. In Table  the experimental results are quoted; they constraint in different ways the neutrino fluxes from the various sources. A fourth equation can be written taking into account the constraints introduced by the solar luminosity.

 

Table:

 

Experiment	Measured flux S.M. expectation	Threshold (MeV)	Equation
Homestake	0.27$\pm$0.06	0.814	$S_c=\Sigma\sigma_{L,c}\phi_i$
Kamiokande	0.44$\pm$0.06	7.5	$S_k=\sigma_k \phi(B)$
Gallium (Gallex, Sage)	0.5 $\pm$ 0.06	0.235	$S_q=\Sigma\sigma_{i,q}\phi_i$
Luminosity			$K=\Sigma (Q/2+<E>_i)Q_i$

 

 

The Kamiokande results, due to its high threshold, constraint only the neutrino flux from⁸B. Homestake and Gallium experiments involve also lower energy neutrino fluxes.

If we try to extract the ⁷Be neutrino flux from the four equations of Table  we obtain a flux negative or very close to zero. In any case the $\nu$ flux from ⁷Be appears to be smaller than the ⁸B flux.

This is in strong contradiction with the sequence of the nuclear reactions within the Sun, where the reaction involving ⁷Be precedes the reaction involving ⁸B and thus the ⁷Be nuclides are in some ways the father than ⁸B. This is the paradox of the present situation of the Solar neutrino problem.