We report on a high-statistics measurement of the basic double pionic fusion reaction $pn \to d\pi^0\pi^0$ over the energy region of the so-called ABC effect, a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The measurements were performed with the WASA detector setup at COSY. The data reveal the ABC effect to be associated with a Lorentzian shaped energy dependence in the integral cross section. The observables are consistent with a resonance with $I(J^P) =0(3^+)$ in both $pn$ and $\Delta\Delta$ systems. Necessary further tests of the resonance interpretation are discussed.

翻译：我们报告对所谓的ABC效应的能量区对基本双电聚变反应($pn\to d\pi ⁇ 0\pi ⁇ 0美元)进行高统计测量,ABC效应的能量区是美元和Delta\Delta$系统的明显低质量增强。测量是在COSY的WASA探测器装置下进行的。数据显示ABC效应与Lorentzian形状的能量依赖性有关。观测结果符合美元和Delta\Delta$系统的共振值。讨论了对共振解释进行必要进一步测试的问题。