标题： 直接探测$e^+e^-$碰撞中的味改变中性流 显示英文标题

标题： Direct probes of flavor-changing neutral currents in $e^+e^-$ collisions

摘要： 我们提出一种新方法来研究在$e^+e^-\to D^{*0}$和$e^+e^-\to B_{s}^* $转变中的味改变中性流，将$e^+e^-$碰撞的能量调节到窄矢量共振态$D^{*0}$或$ B_{s}^*$的质量。 我们对标准模型中$e^+e^-\to D^{*0}$的短距离和长距离贡献进行了深入研究，并探讨了在魅夸克区可能的新物理贡献。 尽管这一过程非常罕见，但与$D^0 \to e^+e^-$衰变相比具有明显优势：不存在自旋抑制，并且可以探测更丰富的有效算符。 该提议对$B_{s}^*$的影响也进行了讨论。 显示英文摘要

摘要： We propose a novel method to study flavor-changing neutral currents in the $e^+e^-\to D^{*0}$ and $e^+e^-\to B_{s}^* $ transitions, tuning the energy of $e^+e^-$- collisions to the mass of the narrow vector resonance $D^{*0}$ or $ B_{s}^*$. We present a thorough study of both short-distance and long-distance contributions to $e^+e^-\to D^{*0}$ in the Standard Model and investigate possible contributions of new physics in the charm sector. This process, albeit very rare, has clear advantages with respect to the $D^0 \to e^+e^-$ decay: the helicity suppression is absent, and a richer set of effective operators can be probed. Implications of the same proposal for $B_{s}^*$ are also discussed.