[论文解读] Minicharged Particles at Accelerators: Progress and Prospects

M. de Montigny, Pierre-Philippe A. Ouimet+3 more|arXiv (Cornell University)|Jul 15, 2023

Dark Matter and Cosmic PhenomenaPhysics and Astronomy被引用 3

一句话总结

本文综述了最小电荷粒子（mCPs）的理论框架与实验约束，mCPs是具有亚量子电荷的假设性弱相互作用粒子。文章针对大型强子对撞机（LHC）的MoEDAL-MAPP实验，提供了更新的灵敏度分析，预测在LHC运行3期及未来高亮度LHC运行中，可在95%置信水平下探测到质量为0.45–65 GeV、电荷低至2.5×10⁻³e的mCPs。

ABSTRACT

Minicharged particles (mCPs), hypothetical free particles with tiny electric charges below the elementary charge, $e$, offer a valuable probe of dark sectors and fundamental physics through several clear experimental signatures. Various models of physics beyond the Standard Model predict the existence of such particles, which could help elucidate the ongoing mysteries regarding electric charge quantization and the nature of dark matter. Moreover, a hypothetical scenario involving a small minicharged subcomponent of dark matter has recently been demonstrated as a viable explanation of the anomaly in the 21 cm hydrogen absorption signal reported by the EDGES collaboration. Although several decades of indirect observations and direct experimental searches for mCPs at particle accelerators have led to severe constraints, a substantial window of the mCP mass$\unicode{x2013}$mixing parameter space remains unexplored at the energy frontier accessible to current state-of-the-art accelerators, such as the Large Hadron Collider (LHC). Consequently, mCPs have remained topical over the years, and new experimental searches at accelerators have been gaining interest. In this article, we review the theoretical frameworks in which mCPs emerge and their phenomenological implications, the current direct and indirect constraints on mCPs, and the present state of the ongoing and upcoming searches for mCPs at particle accelerators. Additionally, we present the results of an updated study of the projected sensitivity of the recently approved (and relocated) Phase-1 detector of the MoEDAL's Apparatus for Penetrating Particles (MAPP) experiment to Drell$\unicode{x2013}$Yan pair-produced mCPs at the LHC's Run 3 and the future High-Luminosity LHC.

研究动机与目标

• 综述隐藏 sector与向量门户框架下最小电荷粒子（mCPs）的理论模型。
• 总结高能物理、天体物理与宇宙学领域中mCPs的当前直接与间接实验约束。
• 评估MoEDAL-MAPP实验对LHC中Drell–Yan机制产生的mCPs的预期灵敏度。
• 将MAPP-1探测器的灵敏度与未来其他实验（如milliQan、FORMOSA与SHiP）进行比较。
• 识别当前与未来加速器设施可探测的GeV量级下mCPs尚未探索的参数空间。

提出的方法

• 采用无背景假设，预测MAPP-1探测器对LHC中Drell–Yan机制产生mCPs的灵敏度。
• 利用MadGraph5与FeynRules模拟在质心系能量13.6 TeV下通过Drell–Yan机制产生mCPs的过程。
• 基于mCPs在探测器材料中的电离能损与穿越行为，分析探测器对mCPs的响应。
• 针对LHC运行3期的30 fb⁻¹积分亮度以及未来高亮度LHC的更高亮度，进行灵敏度预测。
• 将结果与现有及计划中的实验（包括milliQan、FORMOSA、FLArE与SHiP）进行比较，评估互补性。
• 通过FeynRules验证mCP模型实现，并利用独立模拟进行模型一致性检查。

实验结果

研究问题

• RQ1 在高能物理、天体物理与宇宙学领域，当前对最小电荷粒子（mCPs）的实验约束处于何种状态？
• RQ2 MoEDAL-MAPP实验对LHC运行3期中通过Drell–Yan机制产生的mCPs的灵敏度如何？
• RQ3 在13.6 TeV能量下，MAPP-1探测器在30 fb⁻¹积分亮度下可探测的mCP质量与有效电荷范围为何？
• RQ4 MAPP-1、milliQan、FORMOSA与SHiP在mCP质量–电荷参数空间中的预期灵敏度如何比较？
• RQ5 未来LHC与SPS加速器实验在GeV质量范围内发现mCPs的潜力如何？

主要发现

• MAPP-1探测器预计可在LHC运行3期中以95%置信水平探测到质量在0.45 GeV至65 GeV之间的mCPs。
• 该实验对有效电荷低至2.5×10⁻³e的mCPs具有探测灵敏度，显著低于基本电荷。
• 在高亮度LHC阶段，MAPP-1的灵敏度预计将显著提升，超越当前在GeV质量范围的约束。
• FORMOSA-II探测器预计在mCP探测方面将优于milliQan、MAPP-1与FerMINI实验。
• SHiP实验预计可探测质量范围为0.1至5 GeV的mCPs，灵敏度较当前界限提高一个数量级。
• MAPP-1实验的预期灵敏度与milliQan和FORMOSA-I相当，且在mCP参数空间中与FLArE和SHiP形成互补。