Z线形挑战：ppm和keV测量
The Z lineshape challenge: ppm and keV measurements
摘要：
FCC-ee通过高精度测量和对禁止和罕见过程以及弱耦合粒子的搜索，为标准模型之外的物理学提供了直接或间接证据的强大机会。FCC-ee物理计划的一个关键要素是测量全部$5\times 10^{12}$ Z玻色子的Z线形和具有相对不确定度的$5\times 10^{12}$的束能量校准。利用这个异常大的事件样本，比在Z极的整个LEP1操作期间累积的事件样本大五个数量级，定义参数-$m_{\rm Z}$、$Γ_{\rm Z}$、$N_ν$、$\sin^2θ_{\rm W}^{\rm eff}$、$α_{\rm S}(m_{\rm Z}^2)$，和$α_{\rm QED}(m^2_{\rm Z})$-可以被提取，相对于当前的技术水平，其精确度高达两个数量级。系统误差与统计精度相匹配（Z质量和宽度上的4千电子伏，$\sin^2θ_{\rm W}^{\rm eff}$上的$3\times 10^{-6}$，$α_{\rm QED}$上的相对$3\times 10^{-5}$，以及$α_{\rm S}$上的小于0.0001）导致对对撞机操作、束流仪器、探测器设计、计算设备、理论计算和蒙特卡罗事件发生器的高度苛刻的要求。如此精确的测量还需要创新的分析方法，这需要理论家、实验者和加速器团队之间的共同努力和理解。
英文摘要：
The FCC-ee offers powerful opportunities for direct or indirect evidence for physics beyond the Standard Model, via a combination of high precision measurements and searches for forbidden and rare processes and feebly coupled particles. A key element of FCC-ee physics program is the measurement of the Z lineshape from a total of $5\times 10^{12}$ Z bosons and a beam-energy calibration with relative uncertainty of $10^{-6}$. With this exceptionally large event sample, five orders of magnitude larger than that accumulated during the whole LEP1 operation at the Z pole, the defining parameters - $m_{\rm Z}$, $Γ_{\rm Z}$, $N_ν$, $\sin^2θ_{\rm W}^{\rm eff}$, $α_{\rm S}(m_{\rm Z}^2)$, and $α_{\rm QED}(m^2_{\rm Z})$ - can be extracted with a leap in accuracy of up to two orders of magnitude with respect to the current state of the art. The ultimate goal that experimental and theory systematic errors match the statistical accuracy (4\,keV on the Z mass and width, $3\times 10^{-6}$ on $\sin^2θ_{\rm W}^{\rm eff}$, a relative $3\times 10^{-5}$ on $α_{\rm QED}$, and less than 0.0001 on $α_{\rm S}$) leads to highly demanding requirements on collider operation, beam instrumentation, detector design, computing facilities, theoretical calculations, and Monte Carlo event generators. Such precise measurements also call for innovative analysis methods, which require a joint effort and understanding between theorists, experimenters, and accelerator teams.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
