标题： 在未来的e+e-直线对撞机上，我们能多好地重建ttbar系统在其阈值附近？ 显示英文标题

标题： How Well Can We Reconstruct the ttbar System Near its Threshold at Future e+e- Linear Colliders?

摘要： 我们开发了一种新方法，用于在未来的直线e+e-对撞机上接近阈值时对ttbar系统进行完整的运动学重建。 该方法的核心是似然拟合，旨在提高描述ttbar衰变结果最终态的运动学变量的测量精度。 通过将此方法应用于包含束流辐射、探测器系统的有限接受度和分辨率等各种实验效应的蒙特卡罗ttbar样本，证明了这种改进。 在大多数情况下，拟合将给定运动学变量的广泛非高斯分布转化为近似高斯形状，从而验证了基于部分子级动量简单高斯平滑的表观分析。 为了便于此类表观分析，给出了各种运动学变量的结果分布的标准偏差。 还讨论了运动学拟合方法的可能应用及其预期影响。 显示英文摘要

摘要： We developed a new method for full kinematical reconstruction of the ttbar system near its threshold at future linear e+e- colliders. In the core of the method lies likelihood fitting which is designed to improve measurement accuracies of the kinematical variables that specify the final states resulting from ttbar decays. The improvement is demonstrated by applying this method to a Monte-Carlo ttbar sample generated with various experimental effects including beamstrahlung, finite acceptance and resolution of the detector system, etc. In most cases the fit brings a broad non-Gaussian distribution of a given kinematical variable to a nearly Gaussian shape, thereby justifying phenomenological analyses based on simple Gaussian smearing of parton-level momenta. The standard deviations of the resultant distributions of various kinematical variables are given in order to facilitate such phenomenological analyses. A possible application of the kinematical fitting method and its expected impact are also discussed.