Possible interpretation of theZ_b(10610) andZ_b(10650) in a chiral quark model

Abstract

Abstract. Motivated by the two charged bottomonium-like resonances Z b (10610) and Z b (10650) newly observed by the Belle collaboration, the possible molecular states composed of a pair of heavy mesons, BB, BB * , B * B * , B sB , etc (in S-wave), are investigated in the framework of chiral quark models by the Gaussian expansion method. The bound states BB * and B * B * with quantum numbers I(J P C ) = 1(1 +− ), which are good candidates for the Z b (10610) and Z b (10650) respectively, are obtained. Other three bound states BB * with I(J P C ) = 0(1 ++ ), B * B * with I(J P C ) = 1(0 ++ ), 0(2 ++ ) are predicted. These states may be observed in open-bottom or hiddenbottom decay channel of highly excited Υ. When extending directly the quark model to the hidden color channel of the multi-quark system, more deeply bound states are found. Future experimental search of those states will cast doubt on the validity of applying the chiral constituent quark model to the hidden color channel directly.

Interpretation of Z b (10610) and Z b (10650) in the ISPE mechanism and the Charmonium Counterpart

“…The authors in Ref. [6] further showed that their quantum numbers are I(J P ) = 1(1 + ). The QCD sum rule (QSR) analysis that was developed by Zhang et al [9] suggested that Z b (10610) could be a BB * molecular state.…”

“…The heavy quark spin structure that was developed by Bondar et al [5], the chiral constituent quark model approach in Ref. [6], the effective Lagrangian approach via the one-boson exchange in Ref. [7], and the study of the line shape in the vicinity of B ( * )B( * ) thresholds, as well as two-body decay rates using effective field theory in Ref.…”

Reanalysis of the $$Y(3940)$$ Y ( 3940 ) , $$Y(4140)$$ Y ( 4140 ) , $$Z_c(4020)$$ Z c ( 4020 ) , $$Z_c(4025)$$ Z c ( 4025 ) , and $$Z_b(10650)$$ Z b ( 10650 ) as molecular states with QCD sum rules

“…The Z b (10610) and Z b (10650) appear near the BB * and B * B * thresholds, respectively. It is natural to relate the Z b (10610) and Z b (10650) with the BB * and B * B * molecular states, respectively [24][25][26][27][28][29][30][31][32][33][34][35][36]. Other assignments, such as the tetraquark states [37][38][39], threshold cusps [40], the re-scattering effects [41,42], etc.…”

Possible assignments of the $$X(3872)$$ X ( 3872 ) , $$Z_c(3900)$$ Z c ( 3900 ) , and $$Z_b(10610)$$ Z b ( 10610 ) as axial-vector molecular states

“…In 2013, the Belle collaboration reported the first observation of the decay processes ϒ(5S) → ϒ(1, 2, 3S) π 0 π 0 , and they obtained the neutral particle Z 0 b (10610) in a Dalitz analysis of the decays to ϒ(2, 3S) π 0 [14]. There have been several assignments of the Z b (10610) and Z b (10650), such as the molecular states [15][16][17][18][19][20][21][22][23][24][25], tetraquark states [26,27], threshold cusps [28], rescattering effects [29,30], etc.…”