Search for electron-neutrino transitions to sterile states in the BEST experiment

First results from the BEST Collaboration searching for short-baseline neutrino oscillations to sterile neutrinos with a high-intensity ${}^{51}$Cr monoenergetic neutrino source reaffirm that the so-called gallium anomaly, a deficit in electron neutrinos, persists. $4\ensuremath{\sigma}$ deficits were observed in the ${}^{71}$Ge production rates at two different distance scales, which could be interpreted as oscillations between an electron neutrino and a hypothetical sterile neutrino. The results are consistent with oscillations with a mass squared difference above about 0.5 eV${}^{2}$ and a large mixing angle ${\mathrm{sin}}^{2}\phantom{\rule{0.167em}{0ex}}2\ensuremath{\theta}\ensuremath{\approx}0.4$.