The researchers found the anomaly when they were watching unstable beryllium nuclei decay into photons, which are particles of light.

研究人员在观察不稳定的铍原子核衰变成光子（光子）时发现了这种异常现象。

If the nucleus decayed into the daughter nucleus and an electron, the electron would always have the same momentum, and the same energy.

如果原子核衰变成子核和电子，则电子将始终具有相同的动量和相同的能量。