[PAST EVENT] Shikha Chandra Chaurasia, Physics - Oral Exam for the Ph.D.
Shikha Chandra Chaurasia, Physics - Final Oral Exam for the Ph.D. Title: Beyond the Standard Model: Flavor Symmetry,
Nonperturbative Unification, Quantum Gravity, and Dark Matter
Abstract: This thesis includes a variety of topics beyond the standard model of particle physics, including models of flavor symmetry, unification via a universal Landau pole, emergent gravity, and dark matter. The subject of the talk focuses on a dark matter model in which the dark and visible sectors communicate via a vector-like fermion portal.
We have created a model containing fermionic dark matter that is charged under the simplest non-Abelian dark gauge group and vector-like leptons that also transform under the dark gauge group but have the same electroweak quantum numbers as a right-handed electron, so that they can mix with standard model leptons and serve as a portal between the dark and visible sectors. To avoid the lepton-flavor-violating processes that emerge when the vector-like leptons mix with all three standard model flavors, we identify a mechanism, based on discrete symmetries, that we have called "flavor sequestering." This allows for mixing between the vector-like leptons and a single standard model lepton flavor exclusively, and suppresses unwanted lepton-flavor-violating effects. Consequently the vector-like fermion scale can remain low enough so that this portal can be effective for dark matter annihilation to standard model leptons. We have investigated regions of parameter space that successfully reproduce the dark matter relic density and satisfy current direct detection bounds.
Bio: Shikha Chaurasia was born on August 17, 1991 in Lawrence, Kansas, but basically grew up in Olney, Maryland. She was always fostering an affinity for math and science, but didn't realize it till she tried to step away from it and felt a bit lost. And so she chose to major in physics, astrophysics and math at the College of Charleston, where her passion for these subjects blossomed. She earned her Bachelor of Science degree in May of 2014 and joined William & Mary the following fall for her graduate studies. She obtained her Master of Science in physics in 2016 and began working with Dr. Christopher D. Carone in the theoretical high energy group, where she studied physics beyond the standard model.