Abstract
O(1) eV sterile neutrino can be responsible for a number of anomalous results of neutrino oscillation experiments. This hypothesis may be tested at short base-line neutrino oscillation experiments, several of which are either ongoing or under construction. Here we concentrate on the so-called Gallium anomaly, found by SAGE and GALLEX experiments, and its foreseeable future tests with BEST experiment at Baksan Neutrino Observatory. We start with a revision of the neutrino-gallium cross section, that is performed by utilizing the recent measurements of the nuclear final state spectra. We accordingly correct the parameters of Gallium anomaly and refine the BEST prospects in testing it and searching for sterile neutrinos. We further evolve the previously proposed idea to investigate the anomaly with Zn-65 artificial neutrino source as a next option available at BEST, and estimate its sensitivity to the sterile neutrino model parameters following the Bayesian approach. We show that after the two stages of operation BEST will make 5$\sigma$-discovery of the sterile neutrinos, if they are behind the Gallium anomaly.
Highlights
Sterile neutrinos are hypothetical massive Majorana fermions, singlets with respect to the Standard Model (SM) gauge group, which have been introduced to explain oscillations of the SM neutrinos via mixing with them
We show that after the two stages of operation Baksan experiment on sterile transitions (BEST) will make 5σ discovery of the sterile neutrinos, if they are behind the gallium anomaly
We study the recently proposed idea [5] to perform after a 51Cr-based experiment, the second stage of the BEST operation with the neutrino source based on the isotope 65Zn
Summary
Sterile neutrinos are hypothetical massive Majorana fermions, singlets with respect to the Standard Model (SM) gauge group, which have been introduced to explain oscillations of the SM (or active) neutrinos via mixing with them. Neutrino spectra of 51Cr and 65Zn are significantly different which allows us to achieve a more “uniform” sensitivity to the sterile neutrino parameter space after the BEST subsequent operation with the two artificial sources. In this case, to estimate the BEST sensitivity to sterile neutrino parameters, we calculate the cross section of the process (1) at neutrino energies expected for the 65Zn source. To estimate the BEST sensitivity to sterile neutrino parameters, we calculate the cross section of the process (1) at neutrino energies expected for the 65Zn source To this end, we use the computer program SPECCROS by John Bahcall, which we adapt to account for recent measurements of.
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