Search for B→K[superscript (*)]νν̅ and invisible quarkonium decays

Abstract

We search for the flavor-changing neutral-current decays B→K[superscript (*)]νν̅ , and the invisible decays J/ψ→νν̅ and ψ(2S)→νν̅ via B→K[superscript (*)]J/ψ and B→K[superscript (*)]ψ(2S), respectively, using a data sample of 471×10[superscript 6] BB̅ pairs collected by the BABAR experiment. We fully reconstruct the hadronic decay of one of the B mesons in the Υ(4S)→BB̅ decay, and search for the B→K[superscript (*)]νν̅ decay in the rest of the event. We observe no significant excess of signal decays over background and report branching fraction upper limits of B(B[superscript +]→K[superscript +]νν̅ )<3.7×10[superscript -5], B(B[superscript 0]→K[superscript 0]νν̅ )<8.1×10[superscript -5], B(B[superscript +]→K[superscript *]+νν̅ )<11.6×10[superscript -5], B(B[superscript 0]→K[superscript *0]νν̅ )<9.3×10[superscript -5], and combined upper limits of B(B→Kνν̅ )<3.2×10[superscript -5] and B(B→K[superscript *]νν̅ )<7.9×10[superscript -5], all at the 90% confidence level. For the invisible quarkonium decays, we report branching fraction upper limits of B(J/ψ→νν̅ )<3.9×10[superscript -3] and B(ψ(2S)→νν̅ )<15.5×10[superscript -3] at the 90% confidence level. Using the improved kinematic resolution achieved from hadronic reconstruction, we also provide partial branching fraction limits for the B→K[superscript (*)]νν̅ decays over the full kinematic spectrum.