Measurements of energy-resolved positron-molecule annihilation show the existence of positron binding and vibrational Feshbach resonances. The existing theory describes this phenomenon successfully for the case of infrared-active vibrational modes that allow dipole coupling between the incident positron and the vibrational motion. Presented here are measurements of positron-molecule annihilation made using a recently developed cryogenic positron beam capable of significantly improved energy resolution. The results provide evidence of resonances associated with infrared-inactive vibrational modes, indicating that positron-molecule bound states may be populated by nondipole interactions. The anticipated ingredients for a theoretical description of such interactions are discussed.

中文翻译：

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非偶极正电子-分子相互作用介导的振动费氏共振

能量分辨正电子分子-灭的测量结果表明存在正电子键合和振动Feshbach共振。现有的理论成功地将这种现象描述为红外主动振动模式的情况，该模式允许入射正电子与振动运动之间发生偶极耦合。这里介绍的是使用最近开发的能够显着提高能量分辨率的低温正电子束进行的正电子分子an灭的测量结果。结果提供了与非红外振动模式相关的共振的证据，表明正电子-分子的结合态可能是由非偶极子相互作用引起的。讨论了这种相互作用的理论描述的预期成分。