We investigate the quantum dynamics of target excitation and positronium formation in the positron-hydrogen atom scattering without and with an external assisting laser field within a reduced-dimensional quantum model. Strong interference fringes between the incident and reflected positron wave packets are observed in the reaction region. We further investigate the critical behavior of transition probabilities near the channel-opening thresholds for hydrogen excitation and positronium formation and find a strong competition between channels with similar threshold energies, but different parities. The transmission ratios of the incident positron in different reaction channels are calculated, and it is shown that only positronium formation in the ground state prefers forward scattering. Our simulation of the positron-hydrogen scattering with an assisting laser field indicates that the three-particle bound states can be formed during the collisions due to the photon emission induced by the external laser field.

中文翻译：

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辅助激光场下正电子-氢散射和三体束缚态形成的量子动力学：降维模型的预测

摘要我们在降维量子模型中研究了在没有和有外部辅助激光场的情况下正电子氢原子散射中目标激发和正电子素形成的量子动力学。在反应区域观察到入射和反射正电子波包之间的强干涉条纹。我们进一步研究了氢激发和正电子素形成的通道开放阈值附近跃迁概率的临界行为，并发现具有相似阈值能量但宇称不同的通道之间存在强烈竞争。计算了不同反应通道中入射正电子的透射比，结果表明，只有基态下的正电子素形成才倾向于前向散射。我们用辅助激光场对正电子-氢散射进行的模拟表明，由于外部激光场引起的光子发射，在碰撞过程中可以形成三粒子束缚态。