Quarkonium propagation in the quark–gluon plasma

Abstract

In relativistic heavy ion collisions at RHIC and the LHC, a quark-gluon plasma (QGP) is created for a short duration of about 10 fm/c. Quarkonia (bound states of cc and bb) are sensitive probes of this phase on length scales comparable to the size of the bound states which are less than 1 fm. Observations of quarkonia in these collisions provide us with a lot of information about how the presence of a QGP affects various quarkonium states. This has motivated the development of the theory of heavy quarks and their bound states in a thermal medium, and its application to the phenomenology of quarkonia in heavy ion collisions. We review some of these developments here.

Non-Abelian Electric Field Correlator at NLO for Dark Matter Relic Abundance and Quarkonium Transport

“…The retarded correlation for the electric fields is constructed by applying derivatives on the retarded correlation function of two gauge fields. 10 Evaluating directly in d dimensions, we obtain…”

“…where we have included the two "external" propagators that are present in our original formulation in the Schwinger-Keldysh contour. One can directly check from the path integral that the complete retarded correlation has the structure D R (p)iM R D R (p) in terms 10 At this point, there is a subtlety that needs to be addressed in the definition of the retarded correlation function, because derivatives do not commute with the time-ordering operator that defines the correlator (in this case, a retarded correlation). The usual choice when defining time-ordered correlation functions in QFT textbooks is to take the derivatives outside the time-ordering symbol (i.e., T * -product), because it is this choice that respects Lorentz covariance.…”

Quark–Gluon plasma and heavy-ion phenomenology

“…Collective flow of the final-state hadrons observed in ultra-relativistic heavy-ion collisions or even in smaller systems formed in high-multiplicity pp and p/d/ 3 Henucleus collisions is one of the most important diagnostic tools to probe the initial state of the system and to shed light on the properties of the short-lived, strongly-interacting many-body state formed in these collisions. The evolution of initial state fluctuations leaves imprints on the power spectrum of flow coefficients.…”

“…The behaviour of the heavy quarkonium states in hot strongly interacting matter was proposed as a test of its confining nature, since a sufficiently hot deconfined medium will dissolve any binding between the quarkantiquark pair. A mini-review [3] is restricted to the issue of Quarkonium propagation in QGP.…”

Nonequilibrium evolution of quarkonium in medium

“…In this sense, a quarkonium is a sensitive probe of QGP at higher temperatures, typically determined by its bound state size. During the last decade, there have been a lot of developments in understanding the non-equilibrium evolution of quarkonium in the QGP as an open quantum system [2][3][4], which we summarize in this article.…”