Study of dipion bottomonium transitions and search for the hb(1P)state

Abstract

We study inclusive dipion decays using a sample of 108 × 10 6 Υ ( 3 S ) events recorded with the BABAR detector. We search for the decay mode Υ ( 3 S ) → π + π − h b ( 1 P ) and find no evidence for the bottomonium spin-singlet state h b ( 1 P ) in the invariant mass distribution recoiling against the π + π − system. Assuming the h b ( 1 P ) mass to be 9.900 GeV / c 2 , we measure the upper limit on the branching fraction B [ Υ ( 3 S ) → π + π − h b ( 1 P ) ] < 1.2 × 10 − 4 , at 90% confidence level. We also investigate the χ b J ( 2 P ) → π + π − χ b J ( 1 P ) , Υ ( 3 S ) → π + π − Υ ( 2 S ) , and Υ ( 2 S ) → π + π − Υ ( 1 S ) dipion transitions and present an improved measurement of the branching fraction of the Υ ( 3 S ) → π + π − Υ ( 2 S ) decay and of the Υ ( 3 S ) − Υ ( 2 S ) mass difference.