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 ( n S ) 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 Y b ( 10750 ) , with the mass M ( Y b ) = ( 10752.7 ± 5.9 − 1.1 + 0.7 ) MeV and the Breit-Wigner width Γ ( Y b ) = ( 35.5 − 11.3 − 3.3 + 17.6 + 3.9 ) MeV was observed [1] . We interpret Y b ( 10750 ) as a compact J P C = 1 − − state with a dominant tetraquark component. The mass eigenstate Y b ( 10750 ) is treated as a linear combination of the diquark-antidiquark and b b ¯ 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 Y b and ϒ ( 5 S ) can be estimated from the electronic width, recently determined to be Γ e e ( Y b ) = ( 13.7 ± 1.8 ) eV. The mixing provides a plausible mechanism for Y b ( 10750 ) production in high energy collisions from its b b ¯ component and we work out the Drell-Yan and prompt production cross sections for p p → Y b ( 10750 ) → ϒ ( n S ) π + π − at the LHC. The resonant part of the dipion invariant mass spectrum in Y b ( 10750 ) → ϒ ( 1 S ) π + π − and the corresponding angular distribution of π + -meson in the dipion rest frame are presented as an example.