AI 中文总结
本文通过标准模型分析$D^0$衰变模式，利用因子化和异ospin对称性限制非因子化效应，并预测$D^0→K_{\ m S}^0K_{\ m S}^0$的CP不对称性在千分之一级别。
AI 中文摘要
我们研究了单卡比博压低的粲夸克衰变\(D^0\to \pi^-\pi^+\)、\(D^0\to K^-K^+\)和\(D^0\to K_{\rm S}^0K_{\rm S}^0\)的标准模型描述。利用因子分解和同位旋对称性，我们约束了非因子化效应以及测量分支比所需的相关\(U\)自旋破缺。我们发现\(50\%\)量级的修正足以描述所有模式，这虽可观，但对强子粲夸克衰变并不意外。利用分支比的约束，我们推导了\(D^0\to K_{\rm S}^0K_{\rm S}^0\)中直接\(CP\)不对称性的标准模型预测，发现在我们的基准情景中其至多为千分之一量级，为未来的精确测量提供了动机。
英文摘要
We investigate the Standard Model (SM) description of the singly Cabibbo-suppressed charm decays $D^0\to π^-π^+$, $D^0\to K^-K^+$ and $D^0\to K_{\rm S}^0K_{\rm S}^0$. Using factorisation together with isospin symmetry, we constrain non-factorisable effects and the associated $U$-spin breaking required by the measured branching fractions. We find that corrections of order $50\%$ are sufficient to describe all modes, which although sizeable, are not unexpected for hadronic charm decays. Using the constraints from the branching fractions, we derive SM predictions for the direct CP asymmetry in $D^0\to K_{\rm S}^0K_{\rm S}^0$, finding it to be at most at the per-mille level in our benchmark scenario, providing motivation for future precision measurements.
Comments4 pages, 4 figures. Contribution to the 2026 QCD session of the 60th Rencontres de Moriond
