TauSpinner: a tool for simulating CP effects in H → τ τ decays at LHC
TauSpinner: a tool for simulating CP effects in H → τ τ decays at LHC
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TauSpinner：模拟 LHC 中 H → τ τ 衰变的 CP 效应的工具
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Z. Was
中科院分区：
文献类型：
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作者：
T. Przedzinski;E. Richter;Z. Was
本文讨论了TauSpinner程序包在利用H → ττ衰变通道的横自旋关联测量新发现的Higgs玻色子CP态中的应用.讨论了其主本底Z /γ τ → ττ的应用。TauSpinner软件包允许在权重的帮助下，仅使用来自传出τ轻子及其衰变产物的运动学信息，在已经存在的事件上添加与标量/伪标量状态的任何混合相对应的横向自旋相关性。当τ s衰变的极化矢量和τ对产生的密度矩阵没有与事件样本一起存储时，可以使用该过程。我们专注于希格斯（或类希格斯标量）衰变的明确效应，这些衰变在物理上与产生过程分离。TauSpinner还允许重新引入（或去除）来自Drell-Yan Z /γ π → ττ过程的事件的自旋相关，这是希格斯宇称观测值的主要背景，同样只需要权重的帮助。从文献中，我们回顾了完善的观测，测量希格斯粒子的CP，一个循环的水平，代码的一部分。我们已经开始在目录CP-tests/Z-pi中收集必要的初步结果。首先，我们检查了在[32]的解析形式中，在高能极限中只有对角部分的Rij和极化（Rtz，Rzt）保持非零（见CP-测试/Z-pi/RijS-INTcosthe.根文件的内容），给出了Rij不同分量随不变质量和入射夸克体积的变化曲线。取R ij的模，并在硬散射角上进行积分。在这一确认的鼓励下，我们研究了不同s值和入射夸克矢量的R xx和R yy的比较，但它们是硬散射角余弦的函数（参见CP-测试/Z-pi/Rijcostheta-S=2-6.root和CP-测试/Z-pi/delta12.root文件的内容）。对于较高的s值，R xx和R yy重合。因此，如图4所示，如果样品没有被极化，所产生的背景将具有横向效应（CP希格斯测量所必需的），只要观测结果将对称两个τ衰变系统相对于硬散射平面的总体取向角。
In this paper, we discuss application of the TauSpinner package as a simulation tool for measuring the CP state of the newly discovered Higgs boson using the transverse spin correlations in the H → ττ decay channel. We discuss application for its main background Z /γ ∗ → ττ as well. The TauSpinner package allows to add, with the help of weights, transverse spin correlations corresponding to any mixture of scalar/pseudoscalar state, on already exist-ing events using information from the kinematics of outgoing τ leptons and their decay products only. This procedure can be used when polarimetric vectors of the τ s decays and density matrix for τ -pair production are not stored with the event sample. We concentrate on the well-defined effects for the Higgs (or Higgs-like scalar) decays, which are physically separated from the production processes. TauSpinner also allows to reintroduce (or remove) spin correlations to events from Drell–Yan Z /γ ∗ → ττ process, the main background for the Higgs parity observables, again with the help of weights only. From the literature, we recall well-established observables, developed for measuring the CP of the Higgs, one loop level, segment of the code. We have started to collect the necessary preliminary results in the directory CP-tests/Z-pi . First, we have checked that, as in analytic form of [32], only diagonal parts of R ij and polarization ( R tz , R zt ) remain non zero in the high energy limit (see the contentof CP-tests/Z-pi/RijS-INTcosthe.root file).Plots for different component of R ij are given as a function of invari- ant mass and incoming quark flavor. The module of R ij is taken and integration over the hard scattering angle is performed. Encour- aged by this confirmation we have looked into the comparison of R xx and R yy for different values of s and incoming quark flavors but as function of the cosine of the hard scattering angle (see the content of CP-tests/Z-pi/Rijcostheta-S=2-6.root and CP-tests/Z-pi/delta12.root files). For higher values of s the R xx and R yy were coinciding. Thus, the resulting background will fea-ture,seeFig.4,transversespineffects(necessaryforCPHiggsmeasure-ment)asifthesamplewasnotpolarized,providedthattheobservablewillsymmetrizetheoverallorientationanglecommonforthetwo τ decay systems, with respect to the hard scattering plane.