Selected Publications: In-Medium Similarity Renormalization Group for Open-Shell Nuclei, K. Tsukiyama, S.K. Bogner and A. Schwenk, Phys.Rev. C 85, 061304 (2012).
Testing the density matrix expansion against ab-initio
calculations of trapped neutron drops, S.K. Bogner et al., Phys. Rev. C 84, 044306 (2011).
In-medium similarity renormalization group for nuclei, K. Tsukiyama, S.K. Bogner and A. Schwenk, Phys. Rev. Lett. 106, 222502 (2011).
From low-momentum interactions to nuclear structure, S.K. Bogner, R.J. Furnstahl and A. Schwenk, Prog. Part. Nucl. Phys. 65, 94 (2010).
My research focuses on applications of renormalization group (RG) and effective field theory (EFT) methods to the microscopic description of nuclei and nuclear matter. EFT and RG methods have long enjoyed a prominent role in condensed matter and high energy theory due to their power of simplification for strongly interacting multi-scale systems. More recently, these complementary techniques have become widespread in low-energy nuclear physics, enabling the prospect for model-independent calculations of nuclear structure and reactions with controllable theoretical errors and providing a more tangible link to the underlying quantum chromodynamics.
From a computational perspective, the use of EFT and RG techniques substantially simplifies many-body calculations by restricting the necessary degrees of freedom to the energy scales of interest. In addition to extending the reach of ab-inito calculations by eliminating unnecessary degrees of freedom, many problems become amenable to simple perturbative treatments. Since a mean-field description now becomes a reasonable starting point for nuclei and nuclear matter, it becomes possible to provide a microscopic foundation for extremely successful (but largely phenomenological) methods such as the nuclear shell model and nuclear density functional theory (DFT) that are used to describe properties of the medium-mass and heavy nuclei where ab-inito methods are computationally prohibitive. The use of RG and EFT methods to construct effective nuclear shell model Hamiltonians and energy density functionals from the underlying nuclear force in a major component of the DOE-funded Scientific Discovery thru Advanced Computing (SciDAC) project "Nuclear Computational Low-Energy Initiative (NUCLEI)" of which I am a member.
My research program presents a diverse range of research opportunities for potential Ph.D. students, encompassing three very different (but interrelated) components that offer a balance of analytical and numerical work: 1) inter-nucleon interactions, 2) ab-initio methods for finite nuclei and infinite nuclear matter, and 3) density functional theory for nuclei.
Specific topics that I am currently interested in are: calculating the equation of state for nuclear matter from microscopic inter-nucleon interactions, exploring the role of three-nucleon forces in neutron-rich nuclei, microscopic construction of shell model Hamiltonians and effective operators, developing microscopically based density functional theory for nuclei, and loosely bound systems at the limits of stability.
Ground-state energies of closed shell nuclei without (top) and with (bottom) 3N forces at different resolution scales {lambda}. 3N forces are crucial to reproduce the experimental trend (black bars) in the Calcium isotopes.