| This thesis mainly researched the decay constants and distribution amplitudes ofηandη′mesons with the method of QCD sum rule and constituent quark model.The effect of SU(3) flavor symmetric breaking is considered in our work.QCD sum rule is not only a quite significant non-pertubative method in hadronic physics but also a powerful tool of hadronic physics and nuclear physics.ηandη′are a pair of very interesting mesons and the argument of them has never stopped since they were found in 1961 and 1964 respectively.The value of theη-η′mixing angle in the pseudoscalar-meson nonet has been discussed many times in the last forty years.Quite possibly it has become one of the most interesting to measure SU(3)-breaking hadronic parameters since SU(3) symmetry was proposed.We adopt the similar physics method which is used to deal with theπmeson to calculate the decay constants and distribution amplitudes ofηandη′mesons.We find that the odd moment is canceled and only even moment is non-zero,because the contribution of quark and antiquark for the moments is symmetry in the same constitution quark term (such as(?)u,(?)d and(?)s).Finally we obtain the decay constant ofηmeson,fη=0.168±0.04Gev,and the decay constant ofη′meson, fη′ =0.224±0.006Gev with the same method.Moreover,we figure out the approximate form ofηandη′mesons' twist-2 and twist-3 distribution amplitudes by calculating a few moments of them.Comparing our results withπmeson,we find that theηmeson's distribution amplitude approximation form is close toπmeson's, while theη′meson's distribution amplitude is different toπmeson's. Our results indicate that the SU(3) flavor symmetric breaking has(?)e influence on decay constant ofηmeson,while it has different influence on the distribution amplitude ofηandη′mesons.So we get the conclusion that the SU(3) flavor symmetric breaking should not be ignored in accurate calculation.
|
PDF Full Text Request