Vector manifestation and matter formed in relativistic heavy-ion processes

Recent developments in our description of RHIC and related heavy-ion phenomena in terms of hidden local symmetry theories are reviewed with a focus on the novel nearly massless states in the vicinity of—both below and above—the chiral restoration temperature T c . We present complementary and intuitive ways to understand both Harada–Yamawakiʹs vector manifestation structure and Brown–Rho scaling—which are closely related—in terms of “melting” of soft glues observed in lattice calculations and join the massless modes that arise in the vector manifestation (in the chiral limit) just below T c to tightly bound massless states above T c . This phenomenon may be interpreted in terms of the Bèg–Shei theorem. It is suggested that hidden local symmetry theories arise naturally in holographic dual QCD from string theory, and a clear understanding of what really happens near the critical point could come from a deeper understanding of the dual bulk theory. Other matters discussed are the relation between Brown–Rho scaling and Landau Fermi-liquid fixed point parameters at the equilibrium density, its implications for “low-mass dileptons” produced in heavy-ion collisions, the reconstruction of vector mesons in peripheral collisions, the pion velocity in the vicinity of the chiral transition point, kaon condensation viewed from the VM fixed point, nuclear physics with Brown–Rho scaling, and the generic feature of dropping masses at the RGE fixed points in generalized hidden local symmetry theories.