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Jari Häkkinen

Properties of hadronization in e+e- -annihilation

Abstract:
Possible effects from colour interferences in strong interactions are discussed and investigated, and possible experimental signals in e+e- --> hadrons and e+e- --> W+W- --> hadrons are suggested. The observability of the signals depend on the relative probabilities of the occurrence of interferences, and can provide a measurement of the probabilities. This is important since these probabilities cannot be calculated within perturbative QCD. Models of colour interference are implemented into existing MC programs. An investigation to which extent the spin of initial quarks in e+e- --> Z --> qqbar can be transferred to hadrons formed in the hadronization process is made, and heavy quark fragmentation within the framework of the Lund string model is discussed. A computer program to calculate group theoretical (colour) factors of QCD Feynman diagrams is presented, and the production of deuteron in Upsilon decay and in e+e- --> qqbar events is studied.

Keywords:
hadronization, e+e- -annihilation, colour interferences, strong interactions, QCD, MC programs, heavy quark fragmentation

$\Lambda$-polarization in \epem-annihilation at the Z$^0$-pole G\"osta Gustafson and Jari H\"akkinen, Phys. Lett. B303 350 (1993)

Deuteron production in \epem-annihilation G\"osta Gustafson and Jari H\"akkinen, Z. Phys. C61 683 (1994)

Colour Interference and Confinement Effects in W-pair Production G\"osta Gustafson and Jari H\"akkinen, Z. Phys. C64 659 (1994)

Colour connections in \epem-annihilation Christer Friberg, G\"osta Gustafson, and Jari H\"akkinen, LU-TP 96-10

$\epb \epba$ fragmentation and B$\pi$ correlations Jari H\"akkinen, LU-TP 96-11

Colour: A Computer Program for QCD Colour Factor Calculations Jari H\"akkinen and Hamid Kharraziha, LU TP 96-08

Abstrakt:
M\"ojliga effekter av colour-interferenser i stark v\"axelverkan diskuteras och unders\"oks, m\"ojliga experimentella signaler i e+e- --> hadroner och e+e- --> W+W- --> hadroner f\"oresl{\aa}s. Observerbarheten av signalerna beror p{\aa} den relativa sannolikheten f\"or interferens, och kan d\"arigenom ge en m\"ojlighet att m\"ata eventuell f\"orekomst av interferenser. Denna m\"atning \"ar viktig eftersom de relativa sannolikheterna inte kan ber\"aknas inom st\"ornings-QCD. Modeller f\"or color-interferenser har implementerats i existerande MC-program. En unders\"okning av hur stor del av inital kvark spinet som \"overf\"ors till hadroner som formas i hadroniseringsprocessen utf\"ors, och tungkvarkfragmentering inom lundamodellen diskuteras. Ett datorprogram f\"or ber\"akning av de gruppteoretiska (colour-) faktorerna f\"or QCD feynman- diagram presenteras, samt deutronproduktion i Ypsilon s\"onderfall och i e+e- --> qqba h\"andelser studeras.

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