ar X iv : h ep - p h / 06 01 19 5 v 2 3 A ug 2 00 6 Colour Connection and Diquark Fragmentation in e + e − → cc̄qq̄ → h ′ s Process

The hadronization effects induced by different colour connections of cc̄qq̄ system in e+e− annihilation are investigated by a toy model where diquark fragmentation is employed based on Pythia. It is found that the correlations between the charm baryons and charm antibaryons produced via diquark pair fragmentation are much stronger, and their momentum spectra are harder than those from the standard colour connection in Pythia. keywords: Colour Connection, Diquark, Hadronization The hadronization for partons fragmenting into hadrons is very important, and can only be treated by hadronization models up to now. The colour connection plays a crucial rôle to set the “surface” between the Perturbative Quantum Chromodynamics (PQCD) phase and the hadronization one, while the topic related to the colour connection is beyond the approach of PQCD. It is argued that some clews can be drawn from analyzing the decomposition of the colour space of the final partons produced in PQCD phase [1–3]. For the colour space of the parton system, there are many decomposition ways corresponding to various colour connections, respectively (see, e.g., [4, 5]). Hence, it is instructive to study the special properties of the final hadrons, which could give information for the evidence of specific colour connections. Such kinds of investigation have been made for various parton systems [6–8]. One interesting and important example is the (q1 q̄2 q3 q̄4) system produced via hard collisions. This is the simplest system where many phenomena/mechanisms related to QCD properties could be studied, e.g., (re)combination of quarks in producing special hadrons, influence on reconstruction of intermediate particles (like W±) by soft interaction, etc., most of which more or less relate with the colour connections among the four (anti)quarks. In this letter, the possible colour connections of this system are briefly reviewed. It is pointed out that the hadronization effects of one kind of the colour connections have never been modeled yet. Its special case (diquark pair fragmentation) in e+e− annihilation is investigated in detail. For q1q̄2q3q̄4 system, two of the decomposition ways of its colour space are given as follows: (31 ⊗32)⊗ (33⊗34) = (112 ⊕812)⊗ (134 ⊕834) = (112 ⊗134)⊕ (812 ⊗834)⊕·· · , (1) (31 ⊗34)⊗ (33⊗32) = (114 ⊕814)⊗ (132 ⊕832) = (114 ⊗132)⊕ (814 ⊗832)⊕·· · , (2) [email protected] [email protected] [email protected] [email protected]