From the Higgs to the Cosmos

粒子物理学目前处于一种有趣但令人费解的状态。一方面，粒子物理的标准模型(SM)已经令人难以置信地成功地解释了大量的实验数据，从低能量精度测试到CERN大型强子对撞机(LHC)获得的实验室最高碰撞能量。另一方面，SM无法解释宇宙的物质含量，宇宙似乎主要由暗物质(DM)组成，其次是反物质上的物质过剩。最近在大型强子对撞机上发现的SM预测的希格斯玻色子，也带来了巨大的理论谜题，因为它的质量对量子力学修正极其敏感。这个提议的目标是研究SM之外的新基本粒子和力的理论，这些理论可以解决SM的宇宙学缺陷和希格斯粒子的极端量子敏感性。暗物质构成了宇宙中的大部分物质。然而，DM的确切性质仍然未知，因为它在实验室搜索或天体物理观测中避免了任何决定性的检测。一个可能的原因是，DM比预期的要复杂得多，DM粒子只是与SM相互作用非常弱的整个暗区粒子的一个组成部分。该计划的第一部分是调查暗扇区及其与DM、宇宙学和实验室实验的可能联系。*希格斯玻色子是SM中最鲜为人知的部分。到目前为止获得的数据表明，在大型强子对撞机上发现的新希格斯粒子具有SM希格斯玻色子的性质，但需要一个在大型强子对撞机和其他地方进行精确希格斯研究的程序来完全理解这种新状态。详细的希格斯测量将测试SM的延伸，以解决其质量之谜。此外，搜索奇异的希格斯衰变通道提供了一个非常特殊的机会来发现新的粒子和力，包括那些在黑暗星区的粒子和力。在这个机会的激励下，这个项目的第二部分将研究奇异的希格斯衰变通道，并开发在大型强子对撞机和未来可能的粒子对撞机上观察它们的方法。对希格斯的详细研究也可能有助于解释为什么宇宙中有更多的规则物质而不是反物质。造成这种物质不对称性的最有希望的机制之一是电弱重子产生，在希格斯场驱动的电弱相变过程中产生重子。这种机制在SM中不起作用，但如果在弱标度附近有新的粒子与希格斯玻色子显著相互作用，则可能是可行的。这些粒子通常会改变希格斯粒子的衰减率，甚至可能导致奇异的新衰变通道。这项提议的第三个重点是研究电弱重子发生的机制，以及它们与大型强子对撞机和精密实验的搜索之间的联系。

Particle physics is currently in an interesting but puzzling state. On the one hand, the Standard Model (SM) of particle physics has been incredibly successful at explaining an enormous variety of experimental data, from low-energy precision tests to the highest laboratory collision energies ever achieved at the CERN Large Hadron Collider (LHC). On the other hand, the SM is unable to account for the matter content of the universe, which appears to consist mainly of dark matter (DM) followed by an excess of matter over antimatter. The Higgs boson predicted by the SM, and recently discovered at the LHC, also presents and enormous theoretical puzzle in that its mass is extremely sensitive to quantum mechanical corrections. The goal of this proposal is to investigate theories of new elementary particles and forces beyond the SM that can resolve the cosmological shortcomings of the SM and the extreme quantum sensitivity of the Higgs.******Dark matter makes up the majority of the matter in the universe. However, the precise nature of DM remains unknown as it has avoided any conclusive detection in laboratory searches or astrophysical observations. A possible reason for this is that DM is more complicated than expected, and the DM particle is only one component of an entire dark sector of particles that interact very feebly with the SM. The first part of this program is the investigation of dark sectors and their possible connection to DM, cosmology, and laboratory experiments. ******The Higgs boson is the least understood part of the SM. Data obtained so far suggests that the new Higgs particle found at LHC has the properties of the SM Higgs boson, but a program of precision Higgs studies at the LHC and beyond is needed to fully understand this new state. Detailed Higgs measurements will test extensions of the SM that address the puzzle of its mass. Furthermore, searches for exotic Higgs decay channels present a very special opportunity to discover new particles and forces, including those in a dark sector. Motivated by this opportunity, the second part of this program will investigate exotic Higgs decay channels and develop methods to observe them at the LHC and potential future particle colliders.******Detailed studies of the Higgs may also help to explain why there is more regular matter than antimatter in the universe. One of the most promising mechanisms to create this matter asymmetry is electroweak baryogenesis, in which baryon creation occurs during the electroweak phase transition driven by the Higgs field. This mechanism does not work in the SM, but can be viable if there are new particles near the weak scale that interact significantly with the Higgs boson. These particles will generally modify the decay rates of the Higgs, and may even lead to exotic new decay channels. The third focus of this proposal is the study of mechanisms of electroweak baryogenesis and their connection to searches at the LHC and precision experiments.