Low energy solar neutrinos and spin flavour precession

Abstract

The possibility that the Gallium data effectively indicates a time modulation of the solar active neutrino flux in possible connection to solar activity is examined on the light of spin flavour precession to sterile neutrinos as a subdominant process in addition to oscillations. We distinguish two sets of Gallium data, relating them to high and low solar activity. Such modulation affects principally the low energy neutrinos (pp and 7 Be) so that the effect, if it exists, will become most clear in the forthcoming Borexino and LENS experiments and will provide evidence for a neutrino magnetic moment. Using a model previously developed, we perform two separate fits in relation to low and high activity periods to all solar neutrino data. These fits include the very recent charged current spectrum from the SNO experiment. We also derive the model predictions for Borexino and LENS experiments.

Search for periodicities in theB8solar neutrino flux measured by the Sudbury Neutrino Observatory

“…Because solar rotation should not produce variations in the solar nuclear fusion rate, nonstandard neutrino properties have been proposed as an explanation. For example, the coupling of a neutrino magnetic moment to rotating magnetic fields inside the Sun might cause solar neutrinos to transform into other flavors through a resonant spin flavor precession mechanism [11][12][13]. Periodicities in the solar neutrino flux, if confirmed, could provide evidence for new neutrino physics beyond the commonly accepted picture of matter-enhanced oscillation of massive neutrinos.…”

Two gallium data sets, spin flavour precession and KamLAND

“…Our results are depicted in fig.4 for the best fit LMA+SFP prediction with ∆m 2 21 = 8.2 × 10 −5 eV 2 , tan 2 θ = 0.31 (middle curve), for the set ∆m 2 21 = 8.4 × 10 −5 eV 2 , tan 2 θ = 0.27 (upper curve) and for the LMA best fit, ∆m 2 21 = 7.9 × 10 −5 eV 2 , tan 2 θ = 0.46 (lower curve). For the average source-detector distance of 180 km, as reported by KamLAND, we get from fig.4, P = 0.576 (LMA), 0.623 (Best fit SFP), 0.651 (Table 4 fit) (18) to be compared with the data, P = 0.658 ± 0.064 [23]. Interestingly enough it is seen that the best of the three fits lies in this case for the parameter choice as in table 4, namely the one leading to the Gallium data sets which lie the furthest apart: 74.7 and 60.5 SNU.…”

7Beneutrino signal variation in KamLAND

“…Time variation for 7 Be neutrinos and other low energy neutrinos in the real time experiments BOREXINO and LENS has been examined in [12]. Our main motivation in this work is, as indicated by the title itself, to give predictions for the 7 Be neutrino time variation in KamLAND experiment.…”