Bryn Mawr College
SPS Award for Outstanding Undergraduate Research
Fine Structure Constant Variation
I recently graduated Magna Cum Laude from Bryn Mawr College with honors in physics, minor in mathematics, and a concentration in scientific computing. I was born and raised in Bangladesh. I came to the United States in 2018 to pursue a bachelor's in physics. At the time, I was unsure of what particular area in physics I was interested in. So, over the next four years, I pursued research projects in plasma physics, theoretical physics (string theory), astrophysics, and cosmology. I found my research in cosmology on fine structure constant variation the most exciting as it combined the study of the universe as a whole system with areas of mathematics and data analysis into one enriching, multidisciplinary project by implementing complex numerical evaluation and statistical models to make predictions about the early universe.
I plan to devise exotic numerical tools that can combine a wide range of data and constrain esoteric theories related to both particle physics and the origin of our Universe with the highest precision and sensitivity to date and probe different cosmological phenomena on my next adventure in graduate school.
In some extensions of the standard model of particle physics, the values of the fundamental coupling constants could vary in space and time, as they relate to the size of extra dimensions. Some recent observations of QSO have shown a possibility of time and spatial variation of the fine structure constant, alpha. We analyzed the Bekenstein-Sandvik-Barrow-Magueijo (BSBM) model which places a cosmological scalar field and allows the field and alpha to evolve with the expansion of the universe and a low energy string theory model (Runaway Dilaton) that allows existence of a scalar field (known as Dilaton). Extensions of the scalar field in BSBM and the runaway of the dilaton allow us to consider strong couplings and predict alpha variation across time and space that are consistent with the variation of Hubble parameters allowed by Plank. From those models, we then explore which models are allowed by QSO data by constraining free parameters and couplings. We make predictions for variations in alpha at the surface of last scattering, which could be tested using the Cosmic Microwave Background radiation. After constraining the coupling parameters in both models we find that both models allow alpha variation and a possibility of further constraining Runaway Dilaton couplings using CMB data using Marcov Chains Monte Carlo simulations and principle component analysis.Project leader:
Professor Daniel Grin