2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/37318New preliminary BaBar results for rare leptonic decays $B^- \to K^-ν\barν$ and $B^0\to \ell^+\ell^-$ are reported. Using data collected at the $\FourS$ with the BaBar detector, no evidence for a signal was found yielding the corresponding upper limits at the 90% confidence level: ${\cal B}(B^-\to K^-ν\barν)< 9.4 \times 10^{-5}$ for $50.7 \invfb $, ${\cal B}(\bee)< \eeul$, ${\cal B}(\bmm) < \mmul$ and ${\cal B}(\bem) < \emul$ using $54.4 \invfb $.Latex, 6 pages, 8 figs, two include files *.tex, contribution to FPCP conference replace: added references fixed typosHigh Energy Physics - Experimenttext