论文标题
LHC上顶夸克对的自旋密度矩阵的自旋相关和极化变量与新物理学的比较
Comparison of spin-correlation and polarization variables of spin density matrix for top quark pairs at the LHC and New Physics implications
论文作者
论文摘要
Top-Quark对的精确确定是了解标准模型（SM）期望，通过自旋旋转相关性和极化参数了解有限的新物理（NP）模型的总体一致性的重要工具，并对即将发布的LHC程序的分析策略产生了关键的影响。在这项工作中，我们审查并讨论了各种最先进的蒙特卡洛（MC）方法，例如\ textsc {madgraph5} \ _ amc@nlo，\ textsc {sherpa}，\ textsc {powheg-box}和\ textsc {pythia8}，pythia8}，pytrix element shower（me）$/$/$/$/$/$/$/postor（我）顶级夸克对产生的相关性和极化与最终状态。这是第一项此类研究，不仅比较了不同MC事件发生器方法对旋转密度矩阵元件和极化参数的影响，而且还研究了QCD中领先顺序（LO）和近代领先顺序（NLO）准确性的影响，以及通过\ textsc {sherpa}进行QCD和Electroweak（EW）校正。此外，随着工作的延续，简要概述了NP场景的前景，通过在即将到来的LHC运行期间，通过顶级自旋旋转相关性和超对称性（R平价保守和违反模型）和暗物质（Top Quarks相关的调解人）模型（r奇偶校验和违反模型）的前景进行了简要概述。我们发现，定义变量集的所有SM MC预测通常与不确定性变化中的实验数据和理论预测一致。此外，对于$ \cosφ$的分布，实验室 - 框架可观察物（$ \cosφ_{lab} $和$ |δdation_{ll} | $）以及通过奇偶校验（p）和电荷（p）和收费（cp）生成的可观察结果（cp）（cp），我们得出了一些线索的结论，我们可以将某些线索与实验相距，并且可以与实验相距更加相距。
Precise determination of top-quark pairs is an essential tool for understanding the overall consistency of the standard model (SM) expectations, understanding limited New Physics (NP) models, through spin-spin correlation and polarization parameters, and has a critical impact on the analyses strategies at upcoming LHC programs. In this work, we review and discuss various state-of-the-art Monte Carlo (MC) methodologies as \textsc{MadGraph5}\_aMC@NLO, \textsc{Sherpa}, \textsc{Powheg-Box} and \textsc{Pythia8}, which are Matrix Element (ME)$/$Parton Shower (PS) matching generators including a complete set of spin correlation and polarization in top quark pair production with dileptonic final states. This is the first such study that not only compares the effects of different MC event generator approaches on spin density matrix elements and polarization parameters, but also investigates the effects of leading order (LO) and next-to-leading order (NLO) accuracy in QCD, and electroweak (EW) corrections via \textsc{Sherpa}. Moreover, as a continuation of the work, the prospects for possible NP scenarios through top-quark spin-spin correlation and polarization measurements for Supersymmetry (R parity conserved and violated models) and Dark Matter (top quarks associated mediator) models during upcoming LHC runs are briefly outlined. We find that all SM MC predictions for the defined set of variables are generally consistent with the experimental data and theoretical predictions within the uncertainty variations. Besides, for the distributions of the $\cosφ$, laboratory-frame observables ($\cosφ_{lab}$ and $|Δϕ_{ll}|$) and the observables generated by parity (P) and charge-parity (CP) conserving interactions, we conclude some clues that the considered signals and beyond may well be separated from experimental data and located above the SM predictions.
