B+ --> tau nu and B --> K(*) nu nubar at BaBar and SuperB

TL;DR

This paper reports on BaBar's searches for rare B meson decays involving neutrinos, providing measurements and upper limits, and discusses future prospects with higher luminosity experiments like SuperB.

Contribution

It presents the first measurements and upper limits for B+ --> tau+ nu and B --> K(*) nu nubar decays using hadronic B reconstruction techniques.

Findings

Measured B(B+ --> tau+ nu) = (1.83^{+0.53}_{-0.49} ± 0.24) x 10^{-4}

Upper limits: B(B --> K nu nubar) < 3.2 x 10^{-5}, B(B --> K* nu nubar) < 7.9 x 10^{-5}

Discusses future improvements with SuperB luminosity

Abstract

We present the recent BaBar searches for the leptonic decay B+ --> tau+ nu and for the rare decay B --> K(*) nu nubar, using a data sample of about 470 x 10^6 BB pairs. Both searches use a technique in which one B meson is hadronically reconstructed before searching for evidence of the signal decay in the rest of the event. BaBar measures B(B+ --> tau+ nu) = (1.83 ^{+0.53}_{-0.49} +/- 0.24) x 10^{-4}, and preliminary upper limits at 90% confidence level of B(B --> K nu nubar) < 3.2 x 10^{-5} and B(B --> K* nu nubar) < 7.9 x 10^{-5}. We also discuss the expected observations and precision improvements related to B --> l+ nu and B --> K(*) nu nubar due to the higher luminosity of next generation B Factories like SuperB.