From the Higgs to the Cosmos

粒子物理学目前处于一个有趣但令人困惑的状态。 一方面，粒子物理学的标准模型（SM）在解释大量实验数据方面取得了令人难以置信的成功，从低能精确测试到CERN大型强子对撞机（LHC）有史以来实现的最高实验室碰撞能量。 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，其次是过量的反物质。 希格斯玻色子由SM预测，最近在LHC发现，也提出了巨大的理论难题，因为它的质量对量子力学修正非常敏感。 这个提议的目标是研究新的基本粒子和超越SM的力的理论，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，因为它避免了在实验室搜索或天体物理观测中的任何结论性检测。 一个可能的原因是DM比预期的更复杂，DM粒子只是整个暗区粒子的一个组成部分，它们与SM的相互作用非常微弱。 该计划的第一部分是调查暗区及其与DM，宇宙学和实验室实验的可能联系。 * 希格斯玻色子是SM中最不被理解的部分。 到目前为止获得的数据表明，在LHC发现的新希格斯粒子具有SM希格斯玻色子的性质，但需要在LHC及其他地方进行精确的希格斯研究计划，以充分了解这种新状态。 详细的希格斯测量将测试SM的扩展，以解决其质量之谜。 此外，对奇异希格斯衰变通道的搜索为发现新的粒子和力提供了一个非常特殊的机会，包括那些在暗区的粒子和力。 受这个机会的激励，该计划的第二部分将研究奇异的希格斯衰变通道，并开发在LHC和潜在的未来粒子对撞机上观察它们的方法。对希格斯玻色子的详细研究也可能有助于解释为什么宇宙中的常规物质比反物质多。 创造这种物质不对称性的最有希望的机制之一是电弱重子生成，其中重子的产生发生在希格斯场驱动的电弱相变期间。 这种机制在SM中不起作用，但如果在弱尺度附近有新的粒子与希格斯玻色子发生显着相互作用，则可能是可行的。 这些粒子通常会改变希格斯粒子的衰变率，甚至可能导致新的衰变通道。 该计划的第三个重点是研究电弱重子发生的机制及其与大型强子对撞机和精密实验的联系。

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.