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Nuclear Structure
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. Key scientific themes that are being addressed by my research are
captured by overarching questions:
o What is the nature of the nuclear force that binds protons and neutrons into stable
nuclei and rare isotopes?
o What are the limits of nuclear existence?
o What is the origin of simple patterns in complex nuclei?
o How can our knowledge of nuclei and our ability to produce them benefit the
humankind?
Most of the above physics problems invite a strong interaction between nuclear physics,
many-body-problem, and high- performance computing.
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, that is based on the open quantum system manybody formalism. Solution of this challenging problem has been advanced recently
through the new-generation continuum shell model approaches, in particular the Gamow
Shell Model based on the Berggren ensemble. The recent development of the DensityMatrix Renormalization Group algorithm for open quantum systems within the rigged
Hilbert space formulation of quantum mechanics, enables presently fully converged
configuration interaction calculations.