arXiv 1903.001662019-03-01hep-phhep-ex

从角关联分析二体衰变的一般自旋

General Spin Analysis from Angular Correlations in Two-Body Decays

Seong Youl Choi, Jae Hoon Jeong, Ji Ho Song

备注：: 43 pages, 9 figures

摘要：

确定任何新粒子的自旋并测量它与其他粒子和/或它自身的耦合，对于重建包含该粒子的任何量子场论的结构都是至关重要的。为了诊断三个粒子的动力学性质并确定它们的自旋，本文采用了一种一般的螺旋度形式来描述粒子$Y$在具有极化$X_2$的二体衰变$X_2\to Y X_1$中的极化.我们进行了一个全面的分析，我们特别注重掌握如何充分连接的衰变螺旋度振幅和衰变分布在$X_2$休息框架和那些在实验室框架与$X_2$移动与非零速度通过威克螺旋度旋转的螺旋度状态和振幅。这一理论框架被证明在一个详细的说明性的方式与标准模型（SM）过程，顺序过程$e^-e^+\to Z\to τ^-τ^+$其次是$τ^-\to ρ^-ν_τ\to (π^-π^0)ν_τ$和顺序过程$e^-e^+\to t\bar{t}$其次是$t\to W^+ b \to (\ell^+ν_\ell)b$，和一个非标准的衰变过程的一个新的矢量重顶夸克，$T\to Z t$，其次是$Z\to \ell^-\ell^+$。收集并详细描述了所有直接适用于二体衰变$X_2\to Y X_1$中任何自旋组合和任何类型耦合的有用公式，然后是合适的$Y$二体衰变过程。

英文摘要：

Determining the spin of any new particle and measuring its couplings to other particles and/or itself are crucial in reconstructing the structure of any quantum field theory containing the particle. A general helicity formalism is employed to describe the polarization of the particle $Y$ in a two-body decay $X_2\to Y X_1$ with polarized $X_2$ for the purpose of diagnosing the dynamical properties of three involved particles and for determining their spins altogether. We perform a general and comprehensive analytic analysis with our special focus on grasping fully how to connect the decay helicity amplitudes and decay distributions in the $X_2$ rest frame and those in a laboratory frame with $X_2$ moving with a non-zero velocity through Wick helicity rotation on helicity states and amplitudes. This theoretical framework is demonstrated in a detailed illustrative manner with the Standard Model (SM) processes, the sequential process $e^-e^+\to Z\to τ^-τ^+$ followed by $τ^-\to ρ^-ν_τ\to (π^-π^0)ν_τ$ and the sequential process $e^-e^+\to t\bar{t}$ followed by $t\to W^+ b \to (\ell^+ν_\ell)b$, and one non-standard decay process of a new vectorlike heavy top quark, $T\to Z t$, followed by $Z\to \ell^-\ell^+$. All the useful formulas directly applicable to any combinations of spins and any types of couplings in the two-body decay $X_2\to Y X_1$ followed by suitable $Y$ two-body decays processes are collected and described in detail.

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。

摘要：

英文摘要：

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