B Decays to Two Charmless Pseudoscalar Mesons at CLEO 1

Using 3.3 Million BB̄ pairs accumulated with the CLEO detector we have measured B(B → Kπ) = (1.5 −0.4 ± 0.1± 0.1)× 10, B(B → Kπ) = (2.3 −1.0 ± 0.2± 0.2)× 10, and B(B → η′K+) = (7.8 −2.2±1.0)×10. These constitute the first observations of exclusive B decays to charmless hadronic final states. Furthermore, a measurement of B(B → hπ) = (1.6 +0.3 −0.5 −0.2 ± 0.1) × 10, as well as upper limits on various other B decays to two charmless pseudoscalar mesons are presented. In particular, an upper limit of B(B → ππ) < 1.5 × 10 @ 90%C.L. is placed. All of these results are still preliminary, and averaging over charge conjugate modes is always implied. 1 Presented at XXXIInd Rencontres de Moriond on “QCD and High Energy Hadronic Interactions”, 1997 Figure 1: The dominant decay processes are expected to be a) external W-emission, b)gluonic Penguin, c) internal W-emission, d) external electroweak Penguin.