Belle实验观测到新类粲偶素结构

New charmonium-like states observed in Belle data

摘要: 利用在Υ(nS) (n=1，2，4，5) 共振态及其附近采集的大量数据，Belle实验测量了末态中含两个矢量粒子的双光子过程γγ→J/ψ和ωJ/ψ.在这两个过程中，发现了两个窄共振结构X(4350)和X(3915).这两个新结构的性质目前尚不清楚，可能是普通粲偶素粒子，也可能是含一对粲夸克和一对轻夸克的四夸克态，或含一对粲夸克和一个激发胶子的混杂态，或是由其他未知的动力学原因造成的奇特结构.Belle同时发现在γγ→J/ψ过程中,不存在显著的Y(4140)的信号，实验结果与将Y(4140)解释为四夸克态的部分理论预期有较大差异.

Abstract: Two-photon processes γγ→J/ψ and ωJ/ψ are studied for the first time using data on and off the Υ(nS) (n=1，2，4，5) resonances collected with the Belle detector at the KEKB. Two narrow resonances, X(4350) and X(3915), are observed in these two processes.There are no known charmonium states that match these new observations.They are either new charmonium states,charmonium hybrids or tetraquark states,or produced via other unknown dynamics.No signal for the Y(4140) structure reported by the CDF Collaboration in B+→ K+J/decays is observed in the γγ→J/ψ process.