# A Search for B -> K(*) nu nubar and Invisible Quarkonium Decays

Abstract : We search for the flavor-changing neutral-current decays B->K(*)\nu\nu, and the invisible decays J/psi->\nu\nu\ and psi(2S)->\nu\nu\ via B->K(*)J/psi and B->K(*)psi(2S) respectively, using a data sample of 471 x10^6 BB pairs collected by the BaBar experiment. We fully reconstruct the hadronic decay of one of the B mesons in the Upsilon(4S)->BB decay, and search for the B->K(*)\nu\nu\ decay in the rest of the event. We observe no significant excess of signal decays over background and report branching fraction upper limits of BR(B+->K+\nu\nu)<3.7 x10^-5, BR(B0->K0\nu\nu)< 8.1 x10^-5, BR(B+->K*+\nu\nu)<11.6 x10^-5, BR(B0->K*0\nu\nu)<9.3 x10^-5, and combined upper limits of BR(B->K\nu\nu)<3.2 x10^-5 and BR(B->K*\nu\nu)<7.9 x10^-5, all at the 90% confidence level. For the invisible quarkonium decays, we report branching fraction upper limits of BR(J/psi->\nu\nu)<3.9 x10^-3 and BR(psi(2S)->\nu\nu)<15.5 x10^-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(*)\nu\nu\ decays over the full kinematic spectrum.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00806650
Contributor : Sabine Starita <>
Submitted on : Tuesday, April 2, 2013 - 10:21:36 AM
Last modification on : Tuesday, December 8, 2020 - 1:46:06 PM

### Citation

J.P. Lees, V. Poireau, V. Tisserand, N. Arnaud, M. Davier, et al.. A Search for B -> K(*) nu nubar and Invisible Quarkonium Decays. Physical Review D, American Physical Society, 2013, 87, pp.112005. ⟨10.1103/PhysRevD.87.112005⟩. ⟨in2p3-00806650⟩

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