Theoretical study of atomic collision proscesses under weak interaction

我们开展了μ K能区以下原子碰撞的联合理论研究。在如此低能量的碰撞中。已知相互作用非常弱。散射动力学的计算对所用理论方法的每个数值方面都很敏感。哈佛大学的达尔加诺教授的小组已经发展出了长程卡西米尔力的理论框架。和货车范德华势。Kimura和Shimamura在这方面的研究被认为是世界领先的研究之一。Kimura和Shimamura关注的是在紧耦合方案下散射动力学理论结构的发展。散射动力学非常敏感地依赖于所采用的理论的每一个细节。在数值求解散射问题时需要特别小心。通过将Dalgarno教授小组提出的弱相互作用和长程相互作用结合到Kimura和Shimamura推广的紧耦合方案中，我们成功地求解了具有最小数值不稳定性的耦合方程，得到的散射振幅提供了μ K碰撞能量下散射动力学的丰富信息。有助于理解玻色-爱因斯坦凝聚（BEC）机制。以及BEC中的能量和粒子损失过程。更多的具体应用将在下一阶段的合作中推广。

We have carried out the joint theoretical study on atomic collisions below muK energy region. In such a low energy collision. the interaction is known to be extremely weak. and the calculation for scattering dynamics is sensitive to every numerical aspects of theoretical approach used. Professor Dalgarno's group at Harvard University has developed the theoretical framework for the long-range Casimir force. which is proportional to 1/^7, and the Van der Waals potential. which relates to h/R^6.Their study on this subject is considered to be one of the world leading researches.Kimura and Shimamura have concerned with development of theoretical structure of scattering dynamics within the close coupling scheme.Since the Interaction Is extremely weak and long range. and the scattering dynamics depends very sensitively on every detail of the theory employed. the extreme caution on solving a scattering problem numerically is required.By incorporating weak and long-range interaction developed by Prof.Dalgarno's group into the close coupling scheme extended by Kimura and Shimamura, we have successfully solved the coupled equation with minimum numerical instability, and the scattering amplitudes thus obtained provide ample information of scattering dynamics at muK collision energies.The present results are found to be helpful for understanding the Bose-Einstein condensation (BEC) mechanism. and the energy and particle loss process from the BEC.More specific application will be extended in the next period of the joint collaboration.