Triquark correlations and pentaquarks in a QCD sum rule approach

The role of quark correlations in the description of hadron dynamics in many domains of physics, from low energy dynamics to very hot (dense) systems, is being appreciated. Strong correlations of two quarks (diquark) have been widely investigated in this respect. Recently, we have proposed a dynamical scheme to describe the Theta(+) pentaquark in which also three quark correlations (triquark) were instrumental in producing a low mass exotic state. We perform a study, within the QCD sum rule approach including OPE and direct instanton contributions, of triquark correlations and obtain two quasi-bound light ud (s) over bar color quark clusters of 800 and 930 MeV, respectively. (c) 2005 Elsevier B.V. All rights reserved.