Christian Drischler

Christian Drischler

Assistant Professor of Physics and FRIB-TA Bridge Faculty

Research

I’m a theoretical physicist working at the intersection of nuclear physics and nuclear astrophysics.

My research interests include applications of chiral effective field theory (EFT) and many-body theory to derive microscopic constraints on the nuclear matter equation of state (EOS) and the structure of neutron stars.

I have been developing Bayesian statistical methods and fast & accurate emulators to facilitate rigorous uncertainty quantification and statistically robust comparisons between nuclear theory, observational, and experimental constraints on the EOS obtained in the FRIB and multimessenger era.

I study strongly interacting, strongly correlated matter, ranging from atomic nuclei probed by laboratory experiments to neutron stars observed by multimessenger astronomy. Although the theory of strong interactions, quantum chromodynamics (QCD), describes nuclear matter across all relevant density scales, no microscopic framework is currently available to predict the EOS and composition of the high-density matter in the cores of heavy neutron stars.

While a lot has recently been learned about dense matter through neutron star observation, heavy-ion collisions, and theory predictions, many key questions remain unanswered; for example:

My research, funded by both DOE and NSF, aims to advance our microscopic understanding of the nuclear EOS, the structure and evolution of neutron stars, and the nucleosynthesis of heavy elements in the universe.

To this end, I leverage chiral EFT of low-energy QCD, many-body theory, and state-of-the-art computational methods to solve the nuclear many-body problem with quantified uncertainties. My original research has made significant contributions to nuclear physics and nuclear astrophysics. It has been recognized internationally through research fellowships, awards, and invitations to give plenary talks and write review articles.

Nuclear theory has made tremendous progress in developing chiral EFT into a powerful framework for deriving nuclear forces consistent with the symmetries of low-energy QCD. I have contributed to this progress with several new ideas in chiral EFT, many-body theory, Bayesian machine learning (ML), and their applications to the study of neutron star physics.

My Monte Carlo framework for diagrammatic nuclear matter calculations overcame previously required approximations and limitations using automated diagram evaluation, thereby enabling more accurate EOS predictions with controlled uncertainties. With my BUQEYE collaborators, I set the standard for rigorously quantifying theoretical uncertainties in EOS predictions due to truncating the EFT expansion at a finite order.

These EFT truncation errors grow rapidly with baryon density, and rigorously quantifying them is critical for modeling neutron stars; previous EOS predictions only provided rough uncertainty estimates. My EOS calculations with quantified uncertainties have led to statistically robust predictions for neutron star structure that can be confronted with the wealth of experimental and observational EOS constraints anticipated in the multimessenger era, so advancing our understanding of dense matter.

In the next few years, I aim to take full advantage of multimessenger astronomy, novel experimental campaigns, and advances in nuclear theory to constrain the nuclear EOS at zero and finite temperatures with unprecedented precision. This will shed light on important questions in nuclear astrophysics, such as:

The high computational cost of nuclear many-body calculations will be mitigated by developing fast and accurate emulators using model-reduction methods.

Theoretical modeling of nuclear systems, which are notoriously complex, often includes superfluous information for describing the quantities of interest. Emulators are fast surrogate models that systematically reduce a system’s complexity while accurately approximating high-fidelity models. They are game-changers in applying Bayesian statistical methods to nuclear physics and are actively under study.

My research program is tightly coupled to the Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) and multimessenger observations, both of which will produce a wealth of data in the next decade. I aim to provide rigorous interpretations of these data to obtain a fundamental understanding of dense matter with quantified uncertainties.

This research is naturally collaborative, and I’m grateful to my colleagues in the following collaborations for making this joint endeavor productive, engaging, and exciting:

Interested in EOS physics and fast and accurate emulators for nuclear physics?

If so, please feel free to reach out to me. I’m always happy to discuss this research with anyone interested. In the meantime, let me draw your attention to the following pedagogical review articles for further reading:

I recently gave the recorded Science Café titled The Strong Force Awakens: A Neutron Star Story, which covered many of the mentioned subjects in a generally accessible way.