Topics in QCD Sum Rules

• Main Authors: Kwei-Chou Yang, 楊桂周
• Other Authors: W-Y Pauchy Hwang
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/65992116309331985857

博士 === 國立臺灣大學 === 物理研究所 === 82 === In the method of QCD sum rules, roles played by quark condensates and by the gluon condensate are taken into account in the determination of the properties of hadrons. In this thesis, we use the method of QCD sum rules to calculate hadron properties. The first part is devoted to the neutron-proton mass difference. We attempt to include diagrams consistently up to dimension 9, assuming different up and down current-quark masses, and distinguish between <0.lgvert.:.ubar.u:.lgvert.0> and <0.lgvert.:.dbar.d:.lgvert.0> The second part describes the investigation of both the .DELTA.-N and .SIGMA.-.LAMBDA. mass splittings. In the case of the .Delta.-N mass splitting, our numerical results indicate that the mass splitting is dominated primarily by the quark-gluon condensate <0.lgvert.g_c\bar q .sigma._{.mu..nu.}(.lambda.^a/ 2)G^{.mu..nu.}_a q.lgvert.0>. In the case of .SIGMA.zero-.LAMBDA. mass splitting, we obtain a value of about 66 MeV, which is slightly smaller than the observed value of 77 MeV. In the final part of the thesis, we treat the semileptonic decay of D or B meson into a light meson and leptons, such as, .Bbar. zero .arrr. .pi.^+ e^- ..nu.bar. and D zero .arrr. K^{*-} e^+ .nu.. The application of the QCD sum rule method to such decays enables us to determine the relevant decay form factors in a certain range of q squared. The method allows us to include the strong interaction effects, in the determination of the Kobayashi-Maskawa (KM) matrix elements from the decay data.