AI 中文总结
研究利用量子断层扫描框架，通过扩展标准程序到异常\(Wtb\)顶点，推导角分布，结合极角和方位角可观测量，系统分离\(t\bar{t}\)事件中产生和衰变的CP破坏来源，并展示了相关角特征。
AI 中文摘要
我们开发了一个量子断层扫描框架，用于确定\(t\bar{t}\)事件中可能的CP奇数效应是源于产生过程、衰变过程还是两者皆有。在窄宽度近似下，过程\(I\to t\bar{t}\to b\ell^+\nu\,\bar b\ell^-\bar\nu\)可分解为产生密度矩阵以及顶夸克和反顶夸克衰变密度矩阵。我们将标准断层扫描程序扩展到一般的异常\(Wtb\)顶点，并推导了相应的角分布。极角分布保留其通常的断层扫描形式，可用于重建产生密度矩阵并测试其CP性质。而涉及\(b\) - 轻子衰变平面的专用方位角可观测量包含特征正弦调制，可探测衰变顶点中可能的新CP破坏相互作用。结合这两类可观测量可系统地分离产生和衰变中CP破坏的来源。我们展示了强子对撞机和轻子对撞机上代表性\(t\bar{t}\)产生场景的角特征。
英文摘要
We develop a quantum-tomographic framework for determining whether possible CP-odd effects in $t\bar t$ events originate in production, in decay, or in both. In the narrow-width approximation, the process $I\to t\bar t\to b\ell^+ν\,\bar b\ell^-\barν$ factorises into a production density matrix and top and antitop decay density matrices. We extend the standard tomography procedure to a general anomalous $Wtb$ vertex and derive the corresponding angular distributions. Polar-angle distributions retain their usual tomographic form, up to modifications of the spin-analysing powers, and can therefore be used to reconstruct the production density matrix and test its CP properties. By contrast, dedicated azimuthal observables involving the $b$--lepton decay planes contain characteristic sine modulations that provide linear probes of possible new CP-violating interactions in the decay vertex. Combining the two classes of observables gives a systematic strategy for separating sources of CP violation in production and in decay. We illustrate the resulting angular signatures for representative $t\bar t$ production scenarios at hadron and lepton colliders.
Comments57 pages, 15 figures
