Theory Seminar (High Energy/Cosmology) |
Events During the Week of October 6th through October 13th, 2024
Monday, October 7th, 2024
- Machine Learning Symmetries in Physics from First Principles
- Time: 4:30 pm - 5:30 pm
- Place: 5310 Chamberlin Hall
- Speaker: Konstantin Matchev, University of Florida
- Abstract: Symmetries are the cornerstones of modern theoretical physics, as they imply fundamental conservation laws. The recent boom in AI algorithms and their successful application to high-dimensional large datasets from all aspects of life motivates us to approach the problem of discovery and identification of symmetries in physics as a machine-learning task. In a series of papers, we have developed and tested a deep-learning algorithm for the discovery and identification of the continuous group of symmetries present in a labeled dataset. We use fully connected neural network architectures to model the symmetry transformations and the corresponding generators. Our proposed loss functions ensure that the applied transformations are symmetries and that the corresponding set of generators is orthonormal and forms a closed algebra. One variant of our method is designed to discover symmetries in a reduced-dimensionality latent space, while another variant is capable of obtaining the generators in the canonical sparse representation. Our procedure is completely agnostic and has been validated with several examples illustrating the discovery of the symmetries behind the orthogonal, unitary, Lorentz, and exceptional Lie groups.
- Host: Lisa Everett
Tuesday, October 8th, 2024
- Physical Signatures of Fermion-Coupled Axions
- Time: 11:00 am - 12:00 pm
- Place: 5310 Chamberlin Hall
- Speaker: Alexander J. Millar, Fermilab
- Abstract: While there is an abundance of experiments searching for axion dark matter (DM) via its electromagnetic coupling, there are fewer utilizing its derivative coupling to electrons and nucleons. This direct coupling generates dynamical effects through the fermion spin, and therefore spin-polarized targets are a naturally useful target. We propose using spin-polarized or magnetized analogs of layered dielectric haloscopes, which are sensitive to axions through their coupling to electrons. These novel techniques can be powerful probes at both radio frequencies, with sensitivity to currently unexplored parameter space, and optical frequencies, with sensitivity comparable to current astrophysical bounds.
- Host: Yang Bai
Wednesday, October 9th, 2024
- Non-Thermal Dark Matter and Cosmological Phase Transitions
- Time: 4:00 pm - 5:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Cash Hauptmann, University of Nebraska–Lincoln
- Abstract: I will discuss ongoing work concerning cosmological phase transitions (PTs) and their possible roles in the production of dark matter (DM) and primordial black holes (PBHs). For DM, I have recently proposed a non-thermal production mechanism utilizing supercooled first-order PTs which can enhance the abundance of DM. This enhancement opens the viable DM parameter space to models with higher annihilation cross sections which would have otherwise produced too little DM in the standard thermal scenario. Another interesting consequence of first-order PTs could be an efficient trapping of DM in false vacuum domains, and their subsequent collapse to PBHs. Depending on the energy scale of the PT, these PBHs could make up significant fractions (if not all) of today’s DM abundance. Whatever their byproducts may be, first-order PTs are expected to source stochastic background signals of gravitational waves—potentially probeable by next-generation detectors. With this in mind, all phenomenological results are presented in a robust multi-messenger fashion; correlating DM or PBH constraints with gravitational wave signals.
- Host: Lisa Everett
Thursday, October 10th, 2024
- No events scheduled
Friday, October 11th, 2024
- No events scheduled