Project Title: Research in Fundamental High Energy Physics at UC Berkeley

Principal Investigator: Prof. Raphael Bousso

Address: Department of Physics, 366 Physics North, University of California, Berkeley, CA 94720

Description: This project consists of three tasks. 

Task A: Gravitational Hologram: PI Bousso. 

The Holographic Principle has emerged as a central element in our search for a unified theory of quantum gravity. Recently, the notion of entanglement wedge (a region encoded by the quantum gravity theory) was generalized from Anti-de Sitter space to arbitrary spacetimes, including our own universe. We will study how information is holographically encoded on surfaces inside the spacetime, and whether and how it can be summoned nonlocally. We will also study the quantum information aspects of generalized entanglement wedges, such as complexity of reconstruction in arbitrary spacetimes, and the puzzling feature that the one-shot min- and max-wedges can already differ at the classical level.  A key conjecture in holography is that black holes can be described by ordinary quantum systems. Probing this conjecture is a main objective of this task. We will study how quantum gravity corrections affect the spectrum of black hole microstates and the Hawking radiation measured by an outside observer. For supersymmetric black holes, we will advance localization techniques to compute their ground state degeneracies in a variety of examples. Ensuring that these degeneracies are integer is a critical check of the key conjecture and serves as an example of exact holography. 

Task B: Shedding Light on the Dark Universe: Co-PI Safdi.

Safdi will perform theoretical research to further the search for particle dark matter (DM) and dark sector physics. The PI will focus on connecting motivated particle physics models for DM with astrophysical and laboratory data to constrain their parameter spaces or lead to detections.  The majority of this task will focus on two well-motivated DM candidates: axions and weakly interacting massive particles (WIMPs). A smaller fraction of the effort will be devoted to more model-independent probes of particle DM.

Task C: Cosmological Probe of New Physics: Co-PI Dai.

Dai will develop theoretical frames and methodologies required for novel probes of fundamental physics that leverage cosmological observations and complement laboratory searches. Dai will investigate the feasibility of using galaxy surveys to measure cosmic birefringence as a novel probe of ultralight axion-like particles that have a parity-violating Chern-Simons coupling with electromagnetism. Additionally, Dai will develop theory and methodology for exploiting highly magnified extragalactic stars as a unique probe of dark matter clustering on length scales comparable to the size of the Solar System. Such a method can probe dark matter minihalos comprised of the QCD axion particles arising from a Peccei-Quinn phase transition after cosmic inflation.