New BaBar Results on Rare Leptonic B Decays

1 Abstract New preliminary BaBar results for rare leptonic decays B− → K−νν and B → `+`− are reported. Using data collected at the Υ (4S) with the BaBar detector, no evidence for a signal was found yielding the corresponding upper limits at the 90% confidence level: B(B− → K−νν) < 9.4 × 10−5 for 50.7 fb−1 , B(B0 → e+e−) < 3.3 × 10−7, B(B0→ μ+μ−) < 2.0 × 10−7 and B(B0 → e±μ∓) < 2.1× 10−7 using 54.4 fb−1 .