Status of the standard solar model prediction of solar neutrino fluxes
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NEUTRINO PHYSICS AND ASTROPHYSICS (Elementary Particles and Fields. Theory)
Status of the Standard Solar Model Prediction of Solar Neutrino Fluxes* M. Gai** Laboratory for Nuclear Science at Avery Point, University of Connecticut, Groton, USA Received November 23, 2005
Abstract—The Standard Solar Model (BP04) predicts a total 8 B neutrino flux that is 17.2% larger than that measured in the salt phase of the SNO detector (and if it is significant, it will indicate oscillation to sterile neutrinos). Hence, it is important to examine in detail the uncertainties (and values) of inputs to the BP04. Currently, the largest fractional uncertainty is due to the new evaluation of the surface composition of the Sun. We examine the nuclear input on the formation of solar 8 B [S17 (0)] and demonstrate that it is still quite uncertain due to the ill-known slope of the measured astrophysical cross section factor and thus illdefined extrapolation to zero energy. This yields an additional reasonable uncertainty due to extrapolation of +0.0 +0% −3.0 eV b (−14% ). Since a large discrepancy exists between measured as well as predicted slopes, the value of S17 (0) is dependent on the choice of data and theory used to extrapolate S17 (0). This situation must be alleviated by new measurement(s). The “world average” is driven by the Seattle result owing to the very small quoted uncertainty, which we, however, demonstrate to be an overestimated accuracy. We propose more realistic error bars for the Seattle results based on the published Seattle data. PACS numbers : 96.10.+i, 96.40.Tv DOI: 10.1134/S1063778806110019
1. INTRODUCTION The high-precision measurement of neutral-current interactions of “8 B solar neutrinos” in the SNO detector (with added salt) [1] yields the measured flux +0.38 (syst.)×106 cm−2 s−1 , ΦNC = 4.94 ± 0.21 (stat.) −0.34 with a total uncertainty of +8.8 and −8.1%. The most realistic Standard Solar Model (SSM) prediction for the 8 B flux, labeled as BP(04) in [2], is 5.79 × 106 cm−2 s−1 ; hence, ΦSSM (ν) − 1 = 17.2%. ΦSNO
(1)
to 12%) and to what was recognized as a new “stan´ dard solar model problem” vis-a-vis the predicted convective zone [4], and it was shown to be in conflict with SSM predictions based on helioseismology [5]. Hopefully, this large uncertainty due to Z/X will be resolved soon, and there is progress in reducing the error due to S34 (0) (see table), leading to a considerably smaller total error. But at the same time, the errors of nuclear inputs are far from resolved. In this paper, we address the error of a crucial nuclear input, Fractional uncertainties (in %) of predicted 8 B and 7 Be solar neutrino fluxes [3]
It is important to examine whether this discrepancy is significant as it could, for example, indicate (further) oscillation of (solar) electron neutrinos to sterile neutrinos. The uncertainties of the SSM prediction of solar neutrino fluxes were studied by Bahcall and Serenelli [3] as listed in the table. Currently the largest fractional uncertainty of the flux is due to the chemical composition (Z/
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