Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany.
Phys Rev Lett. 2010 Apr 23;104(16):162001. doi: 10.1103/PhysRevLett.104.162001. Epub 2010 Apr 19.
We analyze the Belle data [K. F. Chen (Belle Collaboration), Phys. Rev. Lett. 100, 112001 (2008); I. Adachi (Belle Collaboration), arXiv:0808.2445] on the processes e+ e- --> Upsilon(1S)pi+ pi-, Upsilon(2S)pi+ pi- near the peak of the Upsilon(5S) resonance, which are found to be anomalously large in rates compared to similar dipion transitions between the lower Upsilon resonances. Assuming these final states arise from the production and decays of the J(PC)=1(--) state Y(b)(10,890), which we interpret as a bound (diquark-antidiquark) tetraquark state [bq][bq], a dynamical model for the decays Y(b) --> Upsilon(1S)pi+ pi-, Upsilon(2S)pi+ pi- is presented. Depending on the phase space, these decays receive significant contributions from the scalar 0(++) states, f0(600) and f0(980), and from the 2(++) qq-meson f(2)(1270). Our model provides excellent fits for the decay distributions, supporting Y(b) as a tetraquark state.
我们分析了 Belle 数据 [K. F. Chen（Belle 合作组），Phys. Rev. Lett. 100, 112001 (2008)；I. Adachi（Belle 合作组），arXiv:0808.2445] 中电子-正电子对碰撞过程 Υ(1S)π+π-， Υ(2S)π+π-，这些过程在 Υ(5S)共振峰附近的速率异常大，与较低 Υ 共振之间类似的双介子跃迁相比。假设这些末态来自 J(PC)=1(--)态 Y(b)(10,890)的产生和衰变，我们将其解释为束缚态（重夸克-反重夸克）四夸克态 [bq][bq]，提出了 Y(b)→ Υ(1S)π+π-， Υ(2S)π+π-的衰变模型。根据相空间，这些衰变过程从标量 0(++)态 f0(600)和 f0(980)以及 2(++) qq-介子 f(2)(1270)获得显著贡献。我们的模型为衰变分布提供了极好的拟合，支持 Y(b)作为四夸克态。
