阈值附近耦合道动力学导致的放大同位旋对称性破缺
Amplified Isospin Breaking from Coupled-Channel Dynamics Near Threshold
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中文总结 AI 辅助
该研究明确阈值附近态放大同位旋破缺的动力学起源，以极点留数度量分析，结合X(3872)研究发现其存在邻近伙伴极点W_{c1}，且I=1本征态与影子极点连续相连。
中文摘要 AI 辅助
我们明确了阈值附近态中放大同位旋对称性破缺的动力学起源。采用直接由极点耦合定义的基于极点留数的度量，而非受不同末态运动学影响的衰变可观测量，我们发现仅极点靠近阈值不足以产生大的同位旋破缺：大的同位旋破缺要求伴随的同位旋道存在可观的相互作用。将此方法应用于X(3872)，观测到的大同位旋破缺表明存在一个邻近的伙伴极点W_{c1}，这与之前研究的预测一致。此外，我们发现W_{c1}极点在物理情形下主要影响带电阈值附近的线形状，在同位旋极限下不会演化为纯I=1本征态；相反，该本征态与一个更远的影子极点连续相连。
英文摘要
We identify the dynamical origin of amplified isospin breaking in near-threshold states. Using a pole-residue-based measure defined directly from the pole couplings, rather than from decay observables that are also affected by different final-state kinematics, we show that threshold proximity of the pole alone is insufficient: large isospin breaking requires a sizable interaction in the companion isospin channel. Applied to the $X(3872)$, the observed large isospin breaking points to a nearby partner pole, $W_{c1}$, as predicted in previous studies. In addition, we find that the $W_{c1}$ pole, which predominantly affects the line shapes near the charged threshold in the physical case, does not evolve into the pure $I=1$ eigenstate in the isospin limit; instead, that eigenstate is continuously connected to a more distant shadow pole.
