Tsai Yu-Dai, deNiverville Patrick, Liu Ming Xiong
Fermilab, Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA.
Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA.
Phys Rev Lett. 2021 May 7;126(18):181801. doi: 10.1103/PhysRevLett.126.181801.
We study hidden-sector particles at past (CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration and NuCal), present (NA62, SeaQuest, and DarkQuest), and future (LongQuest) experiments at the high-energy intensity frontier. We focus on exploring the minimal vector portal and the next-to-minimal models in which the productions and decays are decoupled. These next-to-minimal models have mostly been devised to explain experimental anomalies while avoiding existing constraints. We demonstrate that proton fixed-target experiments provide one of the most powerful probes for the MeV to few GeV mass range of these models, using inelastic dark matter (iDM) as an example. We consider an iDM model with a small mass splitting that yields the observed dark matter relic abundance, and a scenario with a sizable mass splitting that can also explain the muon g-2 anomaly. We set strong limits based on the CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration and NuCal experiments, which come close to excluding iDM as a full-abundance thermal dark matter candidate in the MeV to GeV mass range. We also make projections based on NA62, SeaQuest, and DarkQuest and update the constraints of the minimal dark photon parameter space. We find that NuCal sets the only existing constraint in ε∼10^{-8}-10^{-4} regime, reaching ∼800 MeV in dark photon mass due to the resonant enhancement of proton bremsstrahlung production. These studies also motivate LongQuest, a three-stage retooling of the SeaQuest experiment with short (≲5 m), medium (∼5 m), and long (≳35 m) baseline tracking stations and detectors as a multipurpose machine to explore new physics.
我们在高能强度前沿的过去（欧洲核子研究中心 - 汉堡 - 阿姆斯特丹 - 罗马 - 莫斯科合作组以及NuCal实验）、当前（NA62、SeaQuest和DarkQuest实验）和未来（LongQuest实验）的实验中研究隐藏扇区粒子。我们专注于探索最小矢量门户模型以及次最小模型，其中产生和衰变是解耦的。这些次最小模型大多是为了解释实验异常现象同时避开现有约束而设计的。我们以非弹性暗物质（iDM）为例，证明质子固定靶实验为这些模型中兆电子伏特到几个吉电子伏特质量范围提供了最强大的探测手段之一。我们考虑了一个具有小质量分裂且能产生观测到的暗物质遗迹丰度的iDM模型，以及一个具有可观质量分裂且能解释μ子g - 2异常的情景。我们基于欧洲核子研究中心 - 汉堡 - 阿姆斯特丹 - 罗马 - 莫斯科合作组和NuCal实验设定了严格的限制，这些限制几乎排除了iDM作为兆电子伏特到吉电子伏特质量范围内全丰度热暗物质候选者的可能性。我们还基于NA62、SeaQuest和DarkQuest实验进行了预测，并更新了最小暗光子参数空间的约束。我们发现NuCal在ε∼10⁻⁸ - 10⁻⁴区域设定了唯一现有的约束，由于质子轫致辐射产生的共振增强，暗光子质量达到约800兆电子伏特。这些研究还推动了LongQuest实验的开展，它是对SeaQuest实验进行的三阶段改造，配备短（≲5米）、中（∼5米）和长（≳35米）基线跟踪站和探测器，作为一台探索新物理的多用途机器。
