Fundamental Physics with and without Colliders

点击翻译按钮获取中文摘要

Why is gravity so weak compared to the other forces in nature? Are there new extra dimensions? What is Dark Matter and how can its scale be related to the W and Z boson mass scales? Such questions have long been the focus of both Particle Theory and Experiment, culminating to the Large Hadron Collider (LHC). The continued absence of new physics at the LHC corners all our ideas that try to address these questions dynamically. Weinberg's successful prediction of the Cosmological Constant and the emergence of the String Landscape suggested an approach to the hierarchy problem different than dynamics. Such approaches led to theories like Split Supersymmetry which are already being sought at the Large Hadron Collider. This brings Particle Physics to crossroads, with one side leading to dynamical theories like Supersymmetry and composite Higgs, and the other the String Landscape and Split Supersymmetry or just the Standard Model.  I plan to focus on identifying signatures in the data from second run of the LHC that can help decide between this dichotomy.  The field of Particle Theory also tries to address questions that span several orders of magnitude in energy, not just the TeV scale. For example, particles like axions, new long-range forces, and large extra dimensions cannot be probed directly with collider experiments. There have been great advances of technology in many other fields of physics such as atom interferometry, where an atom can find itself in a superposition of quantum states that are separated by roughly 10cm for about 1 sec. I have pioneered novel ways that these technologies can be used to design experiments that look for new interactions in matter and Dark Matter. I am now further exploring how combining the latest technologies in other fields of physics with well motivated theoretical ideas to probe Nature at a size much smaller than that of a collider but with the same potential for high impact.  The long-awaited era of data for Particle Physics also continues with astrophysical observations and cosmic ray experiments like Alpha Magnetic Spectrometer (AMS). Advanced LIGO is being commissioned and promises to be the first experiment to detect gravitational waves. I have showed that through the effect of Black Hole Superradiance it can diagnose the presence of light bosons whose Compton wavelength is similar to that of astrophysical black holes (BHs). Super-radiance forms a gravitational atom between the boson and the BH, whose levels can have exponentially large occupation numbers. Transitions between the levels, as well as boson annihilations in a single level produces monochromatic radiation that can be detected at LIGO. I intend to explore the full potential of this astrophysical probe and how it can probe the QCD axion, the particle that explains the smallness of the electric dipole moment of the neutron and eludes experiments for more than thirty years.