We review recent studies on exotic states at the Belle experiment. Theresults include: (1) The measurement of the cross sections of $\gamma \gamma\to \omega \phi$, $\phi\phi$, and $\omega \omega$ for masses that range fromthreshold to 4.0 GeV. In addition to signals from well established spin-zeroand spin-two charmonium states, there are clear resonant structures belowcharmonium threshold, which have not been previously observed. We report aspin-parity analysis for the new structures; (2) No X(3872) signal is observedin $\eta J/\psi$ or $\gamma \chi_{c1}$ mode in B decays. A narrow peak at3823.5 MeV/$c^2$ (named as $\psi_2$) to $\gamma \chi_{c1}$ with a significanceof 4.2 standard deviations including systematic uncertainty is observed in$B^{\pm} \to K^{\pm} \gamma \chi_{c1}$; (3) The bottomonium states $h_b(1P)$,$h_b(2P)$ and $\Upsilon(1D)$ are observed in the reaction $e^+e^- \to \pi^+\pi^- + X$; (4) The observation of two narrow charged structures (named as$Z_b(10610)$ and $Z_b(10650)$) in the mass spectra of the$\pi^{\pm}\Upsilon(nS) (n=1,2,3)$ and $\pi^{\pm} h_b(mP)$ $(m=1,2)$ pairs thatare produced in association with a single charged pion in Y(5S) decays.
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机译：我们在Belle实验中回顾了有关异国状态的最新研究。结果包括：（1）测量从阈值到4.0 GeV的质量的\\ gamma \ gamma \\ omega \ phi $，$ \ phi \ phi $和$ \ omega \ omega $的横截面。除了来自完善的自旋零和自旋两个charm原子态的信号外，在below阈值以下还存在清晰的共振结构，这是以前从未观察到的。我们报告了新结构的aspin平价分析； （2）在B衰减的$ \ eta J / \ psi $或$ \γ\ chi_ {c1} $模式下未观察到X（3872）信号。在$ B ^ {\ pm}中观察到一个窄峰，峰为3823.5 MeV / $ c ^ 2 $（称为$ \ psi_2 $）至$ \ gamma \ chi_ {c1} $，显着性为4.2标准差，包括系统不确定性\ to K ^ {\ pm} \ gamma \ chi_ {c1} $; （3）在反应$ e ^ + e ^-\至\ pi ^ + \ pi ^-+的反应中观察到了底层状态$ h_b（1P）$，$ h_b（2P）$和$ \ Upsilon（1D）$。 X $; （4）在$ \ pi ^ {\ pm} \ Upsilon（nS）（n = 1）的质谱图中观察到两个狭窄的带电结构（分别为$ Z_b（10610）$和$ Z_b（10650）$） ，2,3）$和$ \ pi ^ {\ pm} h_b（mP）$ $（m = 1,2）$对与Y（5S）衰变中的单个带电离子结合产生。
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