Witold (Witek) Nazarewicz
Atomic nuclei, the core of matter and the fuel of stars, are self-bound collections of protons and neutrons (nucleons) that interact through forces that have their origin in quantum chromo-dynamics. Nuclei comprise 99.9% of all baryonic matter in the Universe. The complex nature of the nuclear forces among protons and neutrons yields a diverse and unique variety of nuclear phenomena, which form the basis for the experimental and theoretical studies. Developing a comprehensive description of all nuclei, a long-standing goal of nuclear physics, requires theoretical and experimental investigations of rare atomic nuclei, i.e. systems with neutron-to-proton ratios larger and smaller than those naturally occurring on earth. The main area of my professional activity is the theoretical description of those exotic, short-lived nuclei that inhabit remote regions of nuclear landscape. This research invites a strong interaction between nuclear physics, many-body-problem, and high- performance computing. Key scientific themes that are being addressed by my research are captured by overarching questions:
How did visible matter come into being and how does it evolve?
How does subatomic matter organize itself and what phenomena emerge?
Are the fundamental interactions that are basic to the structure of matter fully understood?
How can the knowledge and technological progress provided by nuclear physics best be used to benefit society?
Quantum Many-Body Problem
Heavy nuclei are splendid laboratories of many-body science. While the number of degrees of freedom in heavy nuclei is large, it is still very small compared to the number of electrons in a solid or atoms in a mole of gas. Nevertheless, nuclei exhibit behaviors that are emergent in nature and present in other complex systems. For instance, shell structure, symmetry breaking phenomena, collective excitations, and superconductivity are found in nuclei, atomic clusters, quantum dots, small metallic grains, and trapped atom gases.
Although the interactions of nuclear physics differ from the electromagnetic interactions that dominate chemistry, materials, and biological molecules, the theoretical methods and many of the computational techniques to solve the quantum many-body problems are shared. Examples are ab-initio and configuration interaction methods, and the Density Functional Theory, used by nuclear theorists to describe light and heavy nuclei and nucleonic matter.
Physics of Open Systems
Today, much interest in various fields of physics is devoted to the study of small open quantum systems, whose properties are profoundly affected by environment, i.e., continuum of decay channels. Although every finite fermion system has its own characteristic features, resonance phenomena are generic; they are great interdisciplinary unifiers. In the field of nuclear physics, the growing interest in theory of open quantum systems is associated with experimental efforts in producing weakly bound/unbound nuclei close to the particle drip-lines, and studying structures and reactions with those exotic systems. In this context, the major problem for nuclear theory is a unification of structure and reaction aspects of nuclei, which is based on the open quantum system many-body formalism.
Physics of FRIB
The Facility for Rare Isotope Beams will be a world-leading laboratory for the study of nuclear structure, reactions and astrophysics. Experiments with intense beams of rare isotopes produced at FRIB will guide us toward a comprehensive description of nuclei, elucidate the origin of the elements in the cosmos, help provide an understanding of matter in neutron stars and establish the scientific foundation for innovative applications of nuclear science to society. FRIB will be essential for gaining access to key regions of the nuclear chart, where the measured nuclear properties will challenge established concepts, and highlight shortcomings and needed modifications to current theory. Conversely, nuclear theory will play a critical role in providing the intellectual framework for the science at FRIB, and will provide invaluable guidance to FRIB’s experimental programs.
"The limits of the nuclear landscape," J. Erler, N. Birge, M. Kortelainen, W. Nazarewicz, E. Olsen, A.M. Perhac, and M. Stoitsov, Nature 486, 509 (2012).
"Spontaneous fission lifetimes from the minimization of self-consistent collective action," J. Sadhukhan, K.Mazurek, A. Baran, J. Dobaczewski, W. Nazarewicz and J. A. Sheikh, Phys. Rev. C 88, 064314 (2013).
"Shell model in the complex energy plane," N. Michel, W. Nazarewicz, M. Ploszajczak, and T. Vertse, J. Phys. G (Topical Review) 36, 013101 (2009).
"Shape coexistence and triaxiality in the superheavy nuclei," S. Cwiok, P.H. Heenen, and W. Nazarewicz, Nature 433, 705 (2005).