Holographic QCD model for heavy and exotic mesons at finite density: A self-consistent dynamical approach

Abstract

We present a self-consistent dynamical holographic QCD model to investigate the mass spectra and melting behavior of heavy and exotic mesons at finite temperature and finite density. Our approach is based on the Einstein-Maxwell-Dilaton (EMD) framework and incorporates an elsewhere already introduced, albeit by hand, phenomenological non-quadratic dilaton profile. This allows one to capture the non-linear Regge trajectories of heavy-flavor mesons and model certain exotic states. We show how to construct such models by actually solving the coupled Einstein, Maxwell, and dilaton field equations, ensuring mathematical self-consistency to replace any ad-hoc input. At finite temperature, we analyze the confinement-deconfinement transition via a Hawking-Page phase transition. We compute the spectral functions, revealing the sequential melting of quarkonia as the temperature is increased. Extending to finite density, we explore the impact of baryon chemical potential on meson stability, showing significant modifications in spectral peaks and effective potentials that indicate a more rapid melting of mesonic states as the chemical potential increases in the deconfined phase. The dual of the small/large black hole transition now indicates towards a first order phase transition line ending at a second order critical point. Interestingly, the spectral functions smoothly cross this phase transition line.