Coupled Transport Equations for Quarkonium Production in Heavy Ion Collisions

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Motivated by recent applications of the open quantum system formalism to understand quarkonium transport in the quark-gluon plasma, we develop a set of coupled Boltzmann equations for open heavy quark-antiquark pairs and quarkonia. Our approach keeps track of the correlation between the heavy quark-antiquark pair from quarkonium dissociation and thus is able to account for both uncorrelated and correlated recombination. By solving the coupled Boltzmann equations for current heavy ion collision experiments, we find correlated recombination is crucial to describe the data of bottomonia nuclear modification factors. To further test the importance of correlated recombination in experiments, we propose a new observable: $\frac{R_{AA}[\chi_b(1P)]}{R_{AA}[\Upsilon(2S)]}$. Future measurements of this ratio will help distinguish calculations with and without correlated recombination.







Steffen A. Bass

Arts and Sciences Distinguished Professor of Physics

Prof. Bass does research at the intersection of theoretical nuclear and particle physics, in particular studying highly energetic collisions of heavy nuclei, with which one aims to create a primordial state of matter at extremely high temperatures and densities (the Quark-Gluon-Plasma) that resembles the composition of the early Universe shortly after the Big Bang. 

It has been only in the last two decades that accelerators have been in operation that give us the capabilities to create the conditions of temperature and density in the laboratory that are favorable for the Quark-Gluon-Plasma  (QGP) to exist. The Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory and the accompaniment of detector systems were built specifically to observe and study this phase of matter. Similar studies have recently commenced at the CERN Large Hadron Collider. The experiments at RHIC have discovered a new form of ultra-dense matter with unprecedented properties, a plasma composed of unbound quarks and gluons, that appears to behave as a nearly ``perfect liquid.''

Prof. Bass is a leading expert in the phenomenology of the Quark-Gluon-Plasma (QGP) and in knowledge extraction from large scale data sets via computational modeling. He is best known for his work developing a variety of computational models for the description of these ultra-relativistic heavy-ion collisions, as well as for his contributions to the phenomenology of the QGP and the determination of the shear viscosity of the QGP.

 Prof. Bass is a member of the Divisions of Nuclear and Computational Physics of the American Physical Society. He has published more than 160 peer-reviewed articles. He is a member of the Editorial Board of Journal of Physics G: Nuclear and Particle Physics.  In 2014 he was named Outstanding Referee for APS Journals and was elected a Fellow of the American Physical Society.

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