Tetraquark interpretation of the charged bottomonium-like statesZb±(10610)andZb±(10650)and implications

Abstract

We present a tetraquark interpretation of the charged bottomonium-like states Z+-_b(10610) and Z+-_b(10650), observed by the Belle collaboration in the pi+- Upsilon(nS) (n=1,2,3) and pi+- h_b(mP) (m=1,2) invariant mass spectra from the data taken near the peak of the Upsilon(5S). In this framework, the underlying processes involve the production and decays of a vector tetraquark Y_b(10890), e+e- --> Y_b(10890) --> [Z+-_b(10610)pi-+, Z+-_b(10650)pi-+] followed by the decays [Z+-_b (10610), Z+-_b (10650)] --> pi+- Upsilon(nS), pi+- h_b(mP). Combining the contributions from the meson loops and an effective Hamiltonian, we are able to reproduce the observed masses of the Z+-_b(10610) and Z+-_b(10650). The analysis presented here is in agreement with the Belle data and provides crucial tests of the tetraquark hypothesis. We also calculate the corresponding meson loop effects in the charm sector and find them dynamically suppressed. The charged charmonium-like states Z+-_c(3752) and Z+-_c(3882) can be searched for in the decays of the J^{PC}=1^{--} tetraquark state Y(4260) via Y(4260) --> Z+-_c(3752)pi-+ and Y(4260) --> Z+-_c(3882)pi-+, with the subsequent decays (Z+-_c(3752),Z+-_c(3882)) --> (J/psi, h_c)pi+-.