Non-strange dibaryons studied in the γd→π0π0d reaction
Non-strange dibaryons studied in the γd→π0π0d reaction
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γd→π0π0d 反应中研究的非奇异二重子
DOI：
10.1016/j.physletb.2018.12.050
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发表时间：
2018
影响因子：
4.4
通讯作者：
T. Ishikawa et al.
中科院分区：
文献类型：
--
作者：
南條 創;T. Ishikawa et al.
在入射光子能量为0.75GeV~1.15GeV的情况下，实验研究了γd→π0π0d双中性介子的相干光产生。总截面随γd质心能量的变化表现出类共振行为，峰值约为2.47GeV和2.63GeV。测得的氚发射角分布相当平坦，这是准自由π-0-π-0产物结合氚的运动学所不能再现的。在π0 d不变质量分布中，在2.14±0.0 1GeV/c2处观察到一个明显的峰，其宽度为0.0 9±0.0 1GeV/c2.根据两个−0 S的角分布，该态的自旋宇称限制为1+、2+或3 GeV.本工作有力地证明了质量为2.14GeV/c2的等向量双重子共振的存在.2+的指认与理论预言的D12态一致.对π±dπ±d和→π+dπp p反应的πd分波幅度P2 3也有能量依赖性。
Coherent double neutral-pion photoproduction on the deuteron, γ d→ π 0 π 0 d, has been experimentally studied at incident photon energies ranging from 0.75 to 1.15 GeV. The total cross section as a function of the γd center-of-mass energy shows resonance-like behavior, which peaks at approximately 2.47 and 2.63 GeV. The measured angular distribution of deuteron emission is rather flat, which cannot be reproduced by the kinematics of quasi-free π 0 π 0 production with deuteron coalescence. In π 0 d invariant-mass distributions, a clear peak is observed at 2.14±0.01 GeV/c 2 with a width of 0.09±0.01 GeV/c 2. The spin-parity of this state is restricted to 1+, 2+ or 3− from the angular distributions of the two π 0 s. The present work shows strong evidence for the existence of an isovector dibaryon resonance with a mass of 2.14 GeV/c 2. The 2+ assignment is consistent with the theoretically predicted D 12 state, and also with the energy dependence of the πd partial-wave amplitude P 2 3 for the π±d→ π±d and π+ d→ p p reactions.