QCD with adjoint scalars in 2D: properties in the colourless scalar sector

We present a numerical study of an SU(3) gauged 2D model for adjoint scalar fields, defined by dimensional reduction of pure gauge QCD in (2 + 1)D at high temperature. We show that the correlations between Polyakov loops are saturated by two colourless bound states, respectively, even and odd under the Z(2) symmetry related to time reversal in the original theory. Their co ntributions (poles) in correlation functions of local composite operators A n, respectively, of degree n = 2p and 2p + 1 in the scalar fields (p = 1,2) fulfill factorization. The contributions of two particle states (cuts) are detected. Their size agrees with estimates based on a meanfield-like decom position of the p = 2 operators into polynomials in p = 1 operators. In con trast to the naive picture of Debye screening, no sizable signal in any An correlation can be attributed to 1/n times a Debye screening length associa ted with n elementary fields. These results are quantitatively consistent w ith the picture of scalar "matter" fields confined within colourless bounds tates whose residual "strong" interactions are very weak. (C) 2001 Elsevier Science B.V. All rights reserved.