Description
The solar neutrino interaction rate time series exhibits the annual sinusoidal modulation due to the Earth's orbit elliptical shape and could in principle contain other possible modulations due to neutrino physics beyond the Standard Model. Using 10 years of Borexino Phase-II and Phase-III data, we aim to a full spectral analysis from one cycle/year to one cycle/day. Using a frequency analysis performed with the generalized Lomb-Scargle (GLS) periodgram and an unconstrained sinusoidal fit, we prove the ellipticity of the Earth's orbit at more than $5\sigma$ level using solar neutrinos only and we exclude any other significant sinusoidal signal in the Borexino time series other than the annual modulation. The present results prove the longstanding success of Borexino in the precise measurement of the solar neutrino fluxes and provide strong constraints for studying the neutrino physics beyond the standard three-flavor model.
| Collaboration | BOREXINO |
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