The search for millicharged particles, the particles with rational or irrational charges, is one of the central topics of modern physics. It is related to the study of charge quantization, which motivated Dirac Quantization and Grand Unification Theories, and can be a test for string theory and quantum gravity [1].
In this talk, I will give a general intro to millicharged particles and discuss a new way to use it to probe the cosmology of “reheating,” a crucial stage of the Universe after the inflation period [1]. Following the theory and cosmology discussion, I will discuss the millicharge searches internationally [2,3], and more specifically at LANL Lujan Center, to help unveil the aforementioned mysteries in cosmology and fundamental theories.

[1] "Cosmic millicharged particles and reheating probes," https://arxiv.org/abs/2308.07951
[2] "FORMOSA: Looking Forward to Millicharged Dark Sectors," PRD (2021), https://arxiv.org/abs/2010.07941
[3] "Proton Fixed-Target Scintillation Experiment for Millicharge Searches," PRD (2019), https://arxiv.org/abs/1812.03998