Entropic destruction of heavy quarkonium in the quark-gluon plasma

The excitations of a bound state immersed in a strongly coupled system are often delocalized and characterized by a large entropy, so that the state is strongly entangled with the rest of the statistical system. If this entropy S increases with the separation r between the constituents of the bound state, S=S(r), then the resulting entropicforceF=T ∂S/ ∂r (T is temperature) can drive the dissociation process. Lattice QCD indicates a large amount of entropy associated with the heavy quark pair in strongly coupled quark-gluon plasma. This entropy S(r) peaks at temperatures 0.9T_c≤T≤1.5T_c (T_c is the deconfinement temperature) and grows with the inter-quark distance r. This peak in the holographic description arises because the heavy quark pair acts as an eyewitness to the black hole formation in the bulk - the process that describes the deconfinement transition. In terms of the boundary theory, this entropy likely emerges from the entanglement of a "long string" connecting the quark and antiquark with the rest of the system. We argue that the entropic mechanism results in an anomalously strong quarkonium suppression in the temperature range near T_c. This entropic destruction may thus explain why the experimentally measured quarkonium nuclear modification factor at RHIC (lower energy density) is smaller than at LHC (higher energy density), possibly resolving the "quarkonium suppression puzzle" - all of the previously known mechanisms of quarkonium dissociation operate more effectively at higher energy densities, and this contradicts the data.