Investigation of Chirality, Vorticity and Spin Polarization in Heavy ion Collisions

Indiana University, Bloomington IN

Investigators

Abstract

Nuclear matter is at the heart of all visible matter in our universe. While it is known to be built from fundamental particles called quarks and gluons, precisely how the structures and properties of nuclear matter arise from the quarks and gluons remains a big question in fundamental physics. An important way to explore the question is through nuclear collision experiments, ongoing at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), that create a hot "subatomic soup" called quark-gluon plasma (QGP). This project helps understand the QGP by examining its behavior under extremely strong magnetic and vorticity fields. The PI accomplishes this by developing the theoretical description of QGP spin transport under such fields, performing phenomenological simulations to calculate observables, and analyzing the implications from comparison with experimental data. In addition to extracting QGP properties from such study, which is one of the major frontiers in today’s nuclear science, this project provides opportunities for engaging and mentoring graduate and undergraduate students in research as well as for carrying out a variety of public outreach activities. The objective of this project is to investigate novel transport arising from interplay between microscopic particle spin and macroscopic chirality, vorticity and magnetic fields of the bulk matter created in heavy ion collisions. The first component is to quantitatively understand the so-called chiral magnetic effect and associated background correlations. This is done by utilizing the anomalous-viscous fluid dynamics simulation framework, with an emphasis on analyzing the influence of initial nuclear structure inputs. The goal is to achieve an explanation of the latest high-precision isobar collision measurements as well as a coherent interpretation for the signal/background evolution from isobar to gold-gold collisions. The second component aims to advance the hydrodynamic framework with angular momentum as well as to phenomenologically compute spin polarization observables using a combination of hydrodynamic and transport models for a wide range of beam energies. The results offer insights into the latest STAR and HADES data at a few GeV collision energy as well as the similarity and difference between low and high energy collisions. More broadly, the project outcome helps expand our knowledge frontier on spin quantum transport under chirality, vorticity, and magnetic fields for general many-body systems across different disciplines. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.