Interpretation of Yb(10750) as a tetraquark and its production mechanism

Abstract

Recently, the Belle Collaboration has updated the analysis of the cross sections for the processes e+e−→ϒ(nS)π+π− (n=1,2,3) in the e+e− center-of-mass energy range from 10.52 to 11.02 GeV. A new structure, called here Yb(10750), with the mass M(Yb)=(10752.7±5.9−1.1+0.7) MeV and the Breit-Wigner width Γ(Yb)=(35.5−11.3−3.3+17.6+3.9) MeV was observed [1]. We interpret Yb(10750) as a compact JPC=1−− state with a dominant tetraquark component. The mass eigenstate Yb(10750) is treated as a linear combination of the diquark-antidiquark and bb¯ components due to the mixing via gluonic exchanges shown recently to arise in the limit of large number of quark colors. The mixing angle between Yb and ϒ(5S) can be estimated from the electronic width, recently determined to be Γee(Yb)=(13.7±1.8) eV. The mixing provides a plausible mechanism for Yb(10750) production in high energy collisions from its bb¯ component and we work out the Drell-Yan and prompt production cross sections for pp→Yb(10750)→ϒ(nS)π+π− at the LHC. The resonant part of the dipion invariant mass spectrum in Yb(10750)→ϒ(1S)π+π− and the corresponding angular distribution of π+-meson in the dipion rest frame are presented as an example.