Search for new physics on the FASER experiment at the LHC

向前搜索实验（FASER）是一项开创性的基于cern的计划，于2022年夏天开始数据采集，作为大型强子对撞机（LHC）第三次运行的一部分。FASER位于ATLAS实验使用的质子-质子相互作用点下游480米处，专为探索具有长寿命的光和弱相互作用的超标准模型（BSM）粒子而设计，称为长寿命粒子（LLPs）。FASER的仪器配置包括一个配备跟踪器和量热计的圆柱形光谱仪，淹没在0.6特斯拉的磁场中。这项新颖的实验已经积累了大约40/fb的数据，预计到2025年第三轮结束时，将积累超过200/fb的数据。这项研究的主要重点是分析由FASER获得的数据，集中精力寻找长寿的暗光子。这些粒子表现出一种独特的特征，其特征是两个相反的带电高能轨道，起源于探测器内的一个共同顶点。这些轨道拥有一个综合动量，指向10米的混凝土和90米的岩石，到达ATLAS的相互作用点。将利用基本技术进行初步数据分析，并提供初步结果。该项目将包括加强这些初步分析，以提高对暗光子的灵敏度，并探索其他新的物理模型，包括轴子样粒子。先进的多元技术，如神经网络，将被用于开发复杂的分析，旨在优化信号选择和背景还原。这包括整合来自单个探测器组件的信息，建立一个全面的粒子识别框架，显著增强了信号和背景事件的分离。此外，将对拟议的快速射电望远镜实验升级进行可行性研究，其中包括在最先进的设施中安装一个全新的探测器。升级后的FASER实验将在高亮度LHC上收集更大的数据集，为粒子物理领域的突破性发现开辟新的途径。

The Forward Search Experiment (FASER) is a ground-breaking CERN-based initiative that commenced data-taking during the Summer of 2022 as part of Run 3 of the Large Hadron Collider (LHC). Positioned 480 meters downstream of the proton-proton interaction point used by the ATLAS experiment, FASER is specifically designed for the exploration of light and weakly-interacting Beyond Standard Model (BSM) particles characterized by a substantial lifetime, known as Long-Lived Particles (LLPs). FASER's instrumental configuration comprises a cylindrical spectrometer equipped with a tracker and calorimeter, submerged in a 0.6 Tesla magnetic field. This novel experiment has already accumulated approximately 40/fb of data and is anticipated to amass more than 200/fb by the end of Run 3 in 2025.The primary focus of this research is to analyse the data obtained by FASER, concentrating on the quest for Long-Lived Dark Photons. These particles exhibit a distinctive signature characterised by two oppositely charged, high-energy tracks, originating from a common vertex within the detector. These tracks possess a combined momentum pointing back through 10 meters of concrete and 90 meters of rock to the ATLAS interaction point. Initial data analysis utilizing basic techniques will have already been conducted, with preliminary results made available. The project will involve enhancing these preliminary analyses to increase the sensitivity to dark photons and to explore other novel physics models, including axion-like particles.Advanced multivariate techniques, such as neural networks, will be employed to develop sophisticated analyses aimed at optimizing signal selection and background reduction. This includes the integration of information from individual detector components to establish a comprehensive particle identification framework, significantly enhancing the separation of signal and background events.Furthermore, feasibility studies will be conducted for a proposed FASER experiment upgrade, which involves the installation of an entirely new detector in a state-of-the-art facility. This upgraded FASER experiment will collect a substantially larger dataset at the High-Luminosity LHC, opening new avenues for ground-breaking discoveries in the realm of particle physics.