Search for B --> K* nu anti-nu decays

TL;DR

This paper reports a search for the rare decay $B o K^* u ar{ u}$ using a large dataset from the BaBar detector, setting upper limits on the branching fractions of these decays.

Contribution

The study provides the first upper limits on $B o K^* u ar{ u}$ decays using a large data sample at the $S$ resonance.

Findings

No significant signal observed.

Upper limits set at 90% confidence level.

Constraints improve bounds on new physics models.

Abstract

We present a search for the decays $B \to K^{*} \nu \bar{\nu}$ using 454$\times10^{6}$ $B \bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the $mbox{\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}}$ detector at the SLAC PEP-II $B$-Factory. We first select an event sample where one $B$ is reconstructed in a semileptonic or hadronic mode with one charmed meson. The remaining particles in the event are then examined to search for a $B \to K^{*} \nu \bar{\nu}$ decay. The charged $K^{*}$ is reconstructed as $ K^{*+} \to K^0_{\scriptscriptstyle S} \pi^{+}$ or $ K^{*+} \to K^{+} \pi^{0}$; the neutral $K^{*}$ is identified in the $K^{*0} \to K^{+} \pi^{-}$ mode. We establish upper limits at 90% confidence level of $\matchal{B}(B^{+} \to K^{*+} \nu \bar{\nu}) < 8 \times 10^{-5}$, $\matchal{B}(B^{0} \to K^{*0} \nu \bar{\nu}) < 12 \times 10^{-5}$, and $\matchal{B}(B \to K^{*} \nu \bar{\nu}) < 8 \times 10^{-5}$.