利用ATLAS探测器对矢量玻色子散射过程在W±W±->l±l±vv和W±Z->lllv末态中的研究

电弱对称性破缺（EWSB）机制是当前粒子物理中最根本和最重要的问题之一。最近在LHC上一个类似Higgs粒子的发现是高能物理实验在解决这一问题上取得的重大进展，针对EWSB机制的进一步深入研究也成为LHC上最重要的物理课题。在LHC上对矢量玻色子散射（VBS）过程的研究是认识和理解EWSB机制的一个重要的途径。我们提出利用ATLAS探测器在LHC 8TeV(21fb-1）和13-14TeV（75-100 fb-1）pp对撞中对VBS过程在W±W±->l±l±vv和W±Z->lllv末态中进行研究：首先通过这两个末态实现对VBS过程的观测，首次在实验上证实VBS过程的存在；然后分别测量VBS过程在这两个末态中的产生截面及其随反应质心能量的变化，检验标准模型中破坏电弱对称性的Higgs机制，设置反常四次规范耦合上限；最后在W±Z->lllv末态的VBS过程中通过寻找共振态探索新的EWSB机制。

The electro-weak symmetry breaking (EWSB) is one of the most fundamental and important questions in particle physics today. The recent discovery of a Higgs-like boson at the LHC was a major progress in solving this problem. Further studies on EWSB have thus become the most crucial part of the physics program at the LHC. Vector boson scattering (VBS) processes in the pp collisions at the LHC provide a fertile and important ground for studying the EWSB mechanism. We propose to perform VBS studies in the W±W±->l±l±vv and W±Z->lllv final states with the ATLAS detector using 21 fb-1 of 8 TeV and 75-100 fb-1 of 13-14 TeV pp collisions at the LHC. The following studies are planed for the proposed VBS physics program in three steps in line with the increasing of integrated luminosity of pp collisions: (1)observe VBS processes in the W±W±->l±l±vv and W±Z->lllv final states with the full 8TeV dataset and early 14TeV data to establish VBS processes experimentally for the first time; (2)measure the inclusive production cross section of VBS processes in the W±W±->l±l±vv and W±Z->lllv final states, respectively, and the production cross section as a function of center of mass energy of the vector boson scatterings in the two channels, test the Higgs mechanism by comparing the measured cross sections with the predictions of the standard model, set upper limits on the anomalous quartic gauge couplings using the cross section measurements in the two channels; (3)probe EWSB models beyond the Higgs mechanism by searching for new resonances in the W±Z->lllv VBS channel with all available data. We expect a search for resonances in the W±Z->lllv VBS final state with 75-100 fb-1 of 13-14 TeV data would be sensitive to some EWSB models predicting resonances with mass around or lower than 1 TeV.