Understanding the structure of the nuclei has been an ongoing challenge that spans almost a century.
It has been described as the oldest outstanding problem that has had a long and difficult history. Progress has been slow, although efforts were multi-pronged. On one hand there is Yukawa's theory that attempts to describe the physics of the nuclei using protons and neutrons as the degrees of freedom via meson exchanges, leading to the field of nuclear phenomenology. On the other hand, it has been well established that Quantum Chromodynamics is the correct theory of strong interaction. But QCD becomes non-perturbative at low-energies and hence nuclear structure calculations using quarks and gluon degrees of freedom become impossible.
In 1990, Steven Weinberg established the fundamental link between QCD and nuclear phenomenology via Effective Field theories. From a modern point of view, nuclei are the asymptotic bound states of quarks and gluons and are described by the low-energy degrees of freedom, that is, nucleons interacting via pion exchanges. The crucial connection between QCD and nuclear phenomenology comes through the low-energy symmetries of QCD, that is, the spontaneously broken approximate chiral symmetry, resulting in the identification of the pions as the pseudo-Goldstone bosons. The crux of the EFT approach is the decoupling of the long and short distance physics.
One can use similar ideas in the phenomenological sector and decouple the high and low-degrees of freedom via Unitary transformations of the Hamiltonian. In this talk, I will discuss the difficulties in the conventional approaches to nuclear physics and emphasize how modern ideas have revolutionized the field and will enumerate the progress that has been made in the past two decades in addition to highlighting the work that is done here at IIT Madras.
Sunethra is an Assistant Professor at the Department of Physics, IIT Madras. Her main research interests lie in the application of modern ideas of EFT/RG to various nuclear many-body problems, especially to the study of superfluidity in Neutron stars. She has also had some experience applying similar ideas to cold atomic systems in the past. She got her Bachelor's in Physics at Stella Maris College, Chennai and her Master's at IIT Madras. She then went on to do her PhD at the Ohio State University, Columbus, Ohio with Prof. Richard Furnstahl. Her doctoral work focused on the application of EFT/RG ideas to the phenomenological two-body interaction. She did two postdoctoral stints, where she explored problems in low-energy QCD with Prof. Ananthanarayan at CHEP, IISc and the application of RG ideas to cold atomic systems with Prof. Markus Mueller at ICTP, Trieste, Italy.