Quarkonium suppression in heavy-ion collisions: an EFT and open quantum system approach

by Nora brambilla

Monday 4 May 2026, 16:00 → 18:00 Europe/Zurich

4/2-037 - TH meeting room (CERN)

Heavy particles are sensitive probes of strongly interacting hot matter.
Quarkonia— bound states of a heavy quark and antiquark — are endowed with a
hierarchy of nonrelativistic scales which makes them uniquely
well-controlled probes of the quark–gluon plasma.
In this talk I will show how the non-equilibrium evolution of small-radius
quarkonia in the QGP can be described by combining potential
nonrelativistic QCD with the open-quantum-system framework. This leads to
quantum master equations — and, in suitable regimes, to Lindblad equations
— that preserve the quantum and non-Abelian nature of the system. The
medium enters through chromoelectric field correlators, and, in a suitable
limit, through quarkonium transport  coefficients such as the quarkonium
momentum diffusion coefficient and its  dispersive counterpart — which we
compute both in perturbation theory and  on the lattice. The effective
field theory thus  turns equilibrium  first-principles input into a
genuinely real-time, non-equilibrium prediction.
Using the Monte Carlo wave-function method on a realistic (3+1)D
dissipative-hydrodynamic background, we obtain bottomonium nuclear
modification factors for LHC 5.02 TeV Pb–Pb collisions
including dissociation, recombination, and late-time feed-down of excited
states.  The all-orders resummation of the binding-energy-over-temperature
expansion, now in progress, gives the framework full reach in temperature,
brings smaller systems  such as O–O into scope, and lets us follow the
heavy-quark pair as it approaches thermal equilibrium with the medium.