THE STRUCTURE OF MESONS NEAR T_c – THE QCD-TARO COLLABORATION –

Lattice Monte Carlo data versus perturbation theory

“…The interpretation of the well-known discrepancy between g 0 -PT and Monte Carlo ∆β data has been problematic in the past. For example, in [8], a fit was attempted to their ∆β data using a coupling with two free parameters. A good fit was obtained only for an unphysical value of one of these parameters, leaving the explanation of the discrepancy open.…”

Heavy quarkonia at high temperature

“…Different calculations give model dependent results. Some predict a significant decrease [3][4][5][6] while others suggest that the masses stay constant [7] or even rise with temperature [8][9][10]. The assumptions for instance about a temperature dependence of the string tension, σ(T ), the strong coupling constant, α s (T ), the effective quark mass M Q (T ) and the gluon condensate Ω|F µν F µν |Ω = G 2 (T ) primarily depend on perturbation theory and may not be reliable in the temperature region under consideration.…”

“…So far most of the work has been concentrated on the calculation of screening masses obtained from spatial correlators which do not have a direct connection to the physical mass of a resonance as defined for instance by the position of a peak in the spectral function. In recent investigations of the temperature dependent structure in the light mesonic channels screening masses from spatial correlations have been found to differ from effective pole masses from correlations in the Euclidean time direction [9,10]. The mass shift of hadrons made of light quarks is expected to be mainly controlled by chiral symmetry restoration.…”