Thermal spectral functions of heavy and exotic Mesons from a hQCD at finite density

Abstract

In this work, we study spectral functions of heavy and exotic mesons in a self-consistent Einstein-Maxwell-dilaton model at finite temperature and chemical potential, where the dilaton is allowed to back-react on the geometry. A non-quadratic dilaton profile is introduced to reproduce the nonlinear Regge trajectories of heavy-flavor mesons, and the corresponding spectral functions are computed for charmonium, bottomonium, tetraquark, and hybrid channels. In all cases, increasing either temperature or chemical potential suppresses and broadens the quasiparticle peaks, signaling sequential in-medium dissociation; for each radial family, the 2S-like state melts before the 1S-like state. The predicted melting temperatures obey the mass ordering $T_{\rm melt}^{\pi_1(1400)}<T_{\rm melt}^{J/\psi}<T_{\rm melt}^{Z_c(3900)}<T_{\rm melt}^{\Upsilon(1S)}$, with $T_{\rm melt}\simeq 1.08,\ 2.96,\ 4.44$, and $5.93\,T_c$, respectively, so heavier states remain bound up to higher temperatures. These results provide quantitative, testable predictions for heavy-ion experiments probing tetraquark and hybrid mesons in hot and dense QCD matter.