Heavy quarkonium pi(+)pi(-) transitions and a possible b(b)over-barq(q)over-bar state

摘要

pi(+)pi(-) transitions of heavy quarkonia, especially the Y(3S) -> Y(1S) pi(+)pi(-) decay process, are revisited. In the framework of the Chiral Unitary Theory (ChUT), the S wave pi pi final state interaction (FSI) is included. It is found that when an additional intermediate state with J(P) = 1(+) and I = 1 is introduced, not only the pi pi invariant mass spectrum and the cos theta(pi)(*) distribution in the Y(3S) -> Y(1S)pi(+)pi(-) process can simultaneously be well explained, but also a consistent description for other bottomonia pi(+)pi(-) transitions can be obtained. As a consequence, the mass and the width of the intermediate state are predicted. From the quark content analysis, this state should be a bbqq state. (c) 2005 Elsevier B.V. All rights reserved.