用最优传输方法实现连续、精准的夸克衰变标签校准。
Data-Driven, Geometry-Aware Optimal-Transport Calibration of Flavor Tagger

- 将标签校准建模为概率单纯形上的最优传输问题,结合几何感知坐标系。
- 在控制区数据中通过EM算法提取条件目标分布,实现多区域联合拟合。
- 引入线性反馈分析分离数据约束与先验影响,提升校准鲁棒性。
现有的夸克衰变标签校准通常以有限工作点的标度因子或一维判别变量的分箱修正形式提供,难以实现现代标签器多组分输出的连续、事件级校准,导致高性能分析中信息丢失,限制分析仅依赖预设变量。本文提出一种几何感知框架,将标签校准建模为概率单纯形上的最优传输问题,传输映射在等距对数比坐标系中参数化并训练。该坐标系下布雷尼尔传输的二次欧氏代价等价于单纯形上的艾奇森距离,使学习映射在艾奇森几何下诱导最小形变。同时,利用期望最大化(EM)技术从控制区数据中直接提取条件目标分布,可同时拟合多个控制区,使用归一化流建模各夸克成分,并估计区域混合比例。所提取的目标用于训练因式分解的风味传输映射。由于混合比例与灵活成分密度的联合估计存在弱约束方向,进一步引入线性化反馈算子分析,将拟合的组成协方差传播至成分密度,分离出数据主导模式与先验主导模式。基于模拟的闭合性研究显示,在指定控制区和独立验证混合物中均实现更优闭合性。
原文摘要 · Abstract (English)
Flavor-tagging calibrations are often provided either as scale factors measured at a finite set of working points or as binned corrections to a chosen one-dimensional discriminant. However, this approach falls short of providing continuous, event-level calibration across the full multicomponent outputs of modern taggers. This limitation leads to information loss in analyses that demand high-performance flavor tagging, restricting analyses to a limited set of predefined variables. In this work, we propose a geometry-aware framework that formulates flavor-tagger calibration as an optimal transport problem on the probability simplex. The transport maps are parameterized and trained in the isometric log-ratio coordinate system. Because the quadratic Euclidean cost of Brenier transport in this coordinate system is equivalent to the Aitchison distance on the simplex, the learned map induces a minimal deformation under the Aitchison geometry. Furthermore, we extract flavor-conditional target distributions directly from control-region data using an expectation-maximization (EM) technique that simultaneously fits multiple control regions, models each flavor component with a normalizing flow, and estimates the regional mixture fractions. The extracted targets are subsequently used to learn flavor-factorized transport maps. Because the joint estimation of mixture fractions and flexible component densities admits weakly constrained directions, we further introduce a linearized feedback-operator analysis that propagates the fitted composition covariance into the extracted component densities, separating data-constrained modes from those dominated by the composition prior. The simulation-based closure study demonstrates improved closure in dedicated control regions and in independent validation mixtures.
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