New Probes of the Ultra-Light Frontier

该奖项为加州大学伯克利分校的Surjeet Rajendran教授的研究活动提供资金。 物理定律经常导致新的粒子，它们的影响通过这些粒子在自然界中表现出来。例如，我们之所以会感受到电力，是因为携带电荷的粒子（如电子和质子）的存在，它们之间的力由光子携带。因此，对粒子的研究是发现新的基本力的一种富有成效的方法。重要的是要寻找这样的基本力量，因为它们有可能大大提高我们对自然规律起源的理解。它们还可能使我们能够以全新的方式与自然世界互动，可能会像电磁学对我们日常生活的影响一样令人瞩目。许多基础物理学模型都预测存在质量很小的粒子，它们与我们的世界的相互作用也很弱。在某些情况下，这些粒子也可能是宇宙的暗物质。它们的弱相互作用可以通过大型系统或精密技术来克服。该项目开发的方法，使用大型天体物理对象，如毫秒天体，以及精密的实验室技术，以显着扩大我们的范围到这些粒子的参数空间。Rajendran教授将开发新的实验方法来检测超轻粒子，与标准模型非常弱的相互作用，如轴子和暗光子。这些粒子自然地出现在标准模型之外的许多物理框架中，甚至可能是宇宙的暗物质。Rajendran教授开发的方法包括使用旋转系统的超辐射不稳定性的存在来论证某些类型的光粒子的存在会导致毫秒双星的快速自旋。因此，对这些粒子的观测可以限制这些粒子。 Rajendran教授将指出暗光子从其纵向模式中出现的定性新效应。这些效应在文献中被忽视了，通过将它们纳入其中，他将展示现有实验如何参数化地将其范围扩展到此类模型的参数空间中。这些收获也延伸到这种暗光子构成宇宙暗物质的情况，他将发明专门用于探测这种暗物质的技术。Rajendran教授还将展示目前已经开发的用于寻找CPT违反的基本来源或宇宙学首选方向的实验方法如何也可以用于寻找某些类型的光暗物质。暗物质的信号可能与这些实验中通常预期的信号在性质上不同，并且可能允许克服这些实验的系统限制的方法。随着对撞机实验成本的增加，粒子物理学的未来可能同样取决于非对撞机实验，这些实验可以探测远在紫外线之外的隐藏区域。

This award funds the research activities of Professor Surjeet Rajendran at the University of California, Berkeley. Physical laws often lead to new particles through which their effects are manifested on the natural world. For example, we experience the electric force because of the existence of particles like the electron and the proton that carry electric charge, with the force between them carried by the photon. Searches for particles is thus a fruitful way to discover new fundamental forces. It is important to search for such fundamental forces since they have the potential to significantly enhance our understanding of the origins of the laws of nature. They may also potentially enable us to interact with the natural world in dramatically new ways, potentially permitting advances as remarkable as the effects of electromagnetism on our daily lives. Many models of fundamental physics predict the existence of particles that have very small masses and also have very weak interactions with our world. In some cases, these particles can also be the dark matter of the universe. Their weak interactions can be overcome either with large systems or through precision technology. This project develops methods that use large astrophysical objects such as millisecond pulsars as well as precision laboratory techniques to significantly expand our reach into the parameter space of such particles.Professor Rajendran will develop new experimental approaches to detect ultra-light particles that interact very weakly with the standard model such as axions and dark photons. Such particles naturally emerge in many frameworks of physics beyond the standard model, and may even be the dark matter of the universe. The methods developed by Professor Rajendran include the use of the existence of the super-radiant instability of rotating systems to argue that the existence of certain kinds of light particles would cause the rapid spin-down of millisecond pulsars. Observations of such pulsars can therefore constrain these particles. Professor Rajendran will point out qualitatively new effects of dark photons emerging from their longitudinal modes. These effects have been overlooked in the literature and by incorporating them, he will show how existing experiments can parametrically extend their reach into the parameter space of such models. These gains also extend to the case where such dark photons constitute the dark matter of the Universe and he will invent techniques tailored to detect such dark matter. Professor Rajendran will also show how current experimental methodologies that have been developed to search for fundamental sources of CPT violation or a cosmologically preferred direction can also be used to search for certain kinds of light dark matter. The dark matter signal can be qualitatively different from the signals typically expected in these experiments and may permit ways to overcome the systematic limitations of such experiments. With the increasing costs of collider experiments, the future of particle physics may lie as much in non-collider experiments that can probe such hidden sectors that lie far in the ultra-violet.