5 The Problem of Mass : Mesonic Bound States

We discuss the problem of mass, noting that meson masses decrease with increasing scale as the dynamically generated condensate of “soft glue” is melted (Brown/Rho scaling). We then extend the Bielefeld LGS color singlet interaction computed for heavy quarks in a model-dependent way by including the Ampére law velocityvelocity interaction. Parameterizing the resulting interaction in terms of effective strength of the potential and including screening, we find that the masses of π, σ, ρ and A1 excitations, 32 degrees of freedom in all, go to zero (in the chiral limit) as T → Tc essentially independently of the input quark (thermal) masses in the range of 1 − 2 GeV, calculated also in Bielefeld. We discuss other LGS which show q̄q bound states, which we interpret as our chirally restored mesons, for T > Tc.