Doctor of Philosophy, The Ohio State University, 2024, Physics

The practice of nuclear physics is divided into experiment and theory. Experimental nuclear physics makes observations of nuclear properties, such as radii and binding energies, while theoretical nuclear physics interprets the results, assimilates them into broader and more fundamental theories, and counsels the direction of future experimental efforts. In order to learn from experimental data, theoretical nuclear physicists make models to describe interactions between fields under the guidelines of quantum field theory even when there may be no closed mathematical form for those interactions. In cases where such a closed form is lacking (and, indeed, even in some cases where such a form is known) and the physics of interest is confined to a physical regime, the dominant paradigm is that of effective field theory (EFT). A cutoff or cutoffs in some physical variable(s) bound the regime where an EFT seeks to describe physical phenomena, which restricts the degrees of freedom, the constituent fields and interactions available for calculations. Additionally, an EFT preserves the symmetries of the underlying theory to create its own Lagrangian that is an infinite sum including all possible terms compliant with those symmetries. An EFT therefore needs a power-counting scheme that organizes the terms by like magnitude. With the calculation of physical observables from an infinite sum of terms being impossible under any circumstances (and putting to the side the fact that such sums are almost always asymptotic and will diverge given enough terms), EFTs truncate at some order and leave an infinite number of higher-order terms out of calculations; the contribution of these terms to theoretical predictions constitutes the truncation error. The specific instantiation of EFT on which this thesis focuses is chiral effective field theory (χEFT), which treats interactions between protons and neutrons (“nucleons,” collectively) as mediated by the exchange of pions. In χEFT, (open full item for complete abstract)

Committee: Richard Furnstahl (Advisor); Thomas Humanic (Committee Member); Yuri Kovchegov (Committee Member); Louis DiMauro (Committee Member) Subjects: Nuclear Physics; Physics; Statistics