Search for pentaquarks at Belle.pdfVIP

BELLE Search for pentaquarks at Belle R. Mizuk1 1Institute for Theoretical and Experimental Physics, B.Cheremushkinskaya, 25, 117259 Moscow, Russia 4 0 E-mail: mizuk@itep.ru 0 (for the Belle Collaboration) 2 Abstract v o We search for the strange pentaquark Θ+ using kaon interactions in the material of the Belle N detector. No signal is observed in the pKS final state, while in the pK − final state we observe 3 ∼ 1.6 · 104 Λ(1520) → pK − decays. We set an upper limit on the ratio of Θ+ to Λ(1520) yields 2 σ (Θ+)/σ(Λ(1520)) 2% at 90% CL, assuming that the Θ+ is narrow. We also report on searches 2 for strange and charmed pentaquarks in B meson decays. These results are obtained from a v 155 fb−1 data sample collected with the Belle detector near the Υ(4S) resonance, at the KEKB 5 + − 0 asymmetric energy e e collider. 0 1 PACS numbers: 13.25.Hw, 13.75.Jz, 14.20.Jn, 14.20.-c 1 4 0 / x e - p e h : v i X r a Typeset by REVT X 1 E INTRODUCTION Until recently, all reported particles could be understood as bound states of three quarks or a quark and an antiquark. QCD predicts also more complicated configurations such as glueballs gg , molecules qq¯qq¯ and pentaquarks qqq qq¯. Recently, observations of the pen- taquark Θ+ = uudds¯ have been reported in the decay channels K+n [1] and pKS [2]. Many experimental groups have confirmed this observation and the isospin 3/2 members of the same p