Bottomonium spectrum in the relativistic flux tube model

The bottomonium spectrum is far from being established. The structures of higher vector states, including the Upsilon(10580), Upsilon(10860), and Upsilon(11020) states, are still in dispute. In addition, whether the Upsilon(10750) signal which was recently observed by the Belle Collaboration is a normal b (b) over bar state or not should be examined. Faced with such a situation, we carried out a systematic investigation of the bottomonium spectrum in the scheme of the relativistic flux tube (RFT) model. A Chew-Frautschi-like formula was derived analytically for the spin average mass of bottomonium states. We further incorporated the spin-dependent interactions and obtained a complete bottomonium spectrum. We found that the most established bottomonium states can be explained in the RFT scheme. The Upsilon(10750), Upsilon(10860), and Upsilon(11020) could be predominantly the 3(3)D(1), 5(3)5(1), and 4(3)D(1) states, respectively. Our predicted masses of 1F and 1G b (b) over bar states arc in agreement with the results given by the method of lattice QCD, which can be tested by experiments in future. We also compared the RFT model with the quark potential model in detail. The differences of these two kinds of models were discussed.