Search for $B^- \to \Lambda \bar p \nu \bar\nu$ with the BABAR experiment

TL;DR

This study searches for the rare decay process $B^- o extLambda ar{p} u ar{ u}$ using BABAR data, setting an upper limit on its branching fraction due to no significant signal observed.

Contribution

First search for the $B^- o extLambda ar{p} u ar{ u}$ decay using BABAR data, establishing an upper limit on its branching fraction.

Findings

No significant signal observed, consistent with background expectations.

Set an upper limit on the branching fraction at $3.0 imes 10^{-5}$.

Used 424 fb$^{-1}$ of data at the $$ resonance.

Abstract

We search for the rare flavor-changing neutral current process $B^- \to \Lambda {\overline p} \nu{\overline{\nu}}$ using data from the BABAR experiment. A total of 424 fb$^{-1}$ of $e^+e^-$ collision data collected at the center-of-mass energy of the $\Upsilon$(4S) resonance is used in this study, corresponding to a sample of ${(471 \pm 3) \times 10^{6}}$ $B\overline{B}$ pairs. Signal $B^- \to \Lambda {\overline p} \nu{\overline{\nu}}$ candidates are identified by first fully reconstructing a $B^+$ decay in one of many possible exclusive decays to hadronic final states, then examining detector activity that is not associated with this reconstructed $B^+$ decay for evidence of a signal $B^- \to \Lambda {\overline p} \nu{\overline{\nu}}$ decay. The data yield is found to be consistent with the expected background contribution under a null signal hypothesis, resulting in an upper limit of ${{\cal B} (B^- \to \Lambda {\overline p} \nu{\overline{\nu}}) < 3.0\times 10^{-5}}$ at the $90\%$ confidence level.