Dalitz Analysis Of D~0? K~-?~+? And D~0?K_S~0?~0? Decays At Belle

The mixing of neutral D0 mesons and the CP violation are currently a frontier topic in the field of particle physics.The Dalitz-plot results of Do's right-sign(RS)decay provide the necessary input for measurement of the D0-D0 mixing in the wrong-sign(WS)decay via TDDA technique.The weak decay of D0 meson has rich physical information,which is an important way to study the dynamics of charm meson and light hadron spectrum.In this thesis,the Dalitz analysis of D0? K-?+? and Do?KS0?0?decays are performed,which is aimed to study the two-body decay mechanism and the properties of K*and a-family resonances,together with searching for CP violation of Do meson.This thesis is based on an integrated luminosity of 953 fb-1 accumulated by the Belle experiment at KEKB asymmetric e+e-collider.The Do candidates are recon-structed with decay chain D*+?D0?S+,D0? K-?+?,where D*+is from the cc pro-cess.Through a M-Q two-dimensional fit,1 1 1.2k signal candidates are extracted in the signal region.An unbinned maximum likelihood fit is performed to experimental data,from which eight significant intermediate resonance states are determined.K*(1680)-and K2*(1980)-decaying into K-? are observed for the first time,and the S wave in-cluding K0*(1430)-decaying into K? is also observed.The significant contribution of ao(980)? ??' process is confirmed.No CP violation is found in the intermediate resonant processes of D0?K-?+? decay.Normalized with decay of D*+?[D0?K-?+]?S+,the branching ratio of D0?K-?+? is measured for the first time.Fur-thermore,we measured the relative ratio of K*(1680)-?K-? to K*(1680)?K-?0 as 0.11-0.06.0.07.The branching ratio for the decay of D0?[K2*(1980)-?K-?]?+ is measured as(2.2-1.9+1.7)× 10-4,and the branching ratio of D0?K*(892)0? decay is(1.41-0.12+0.13)%.This thesis also uses the above-mentioned method to measure the branching ra-tio of D0?KS0?0? by normalized decay of D*+?[D0?KS0?0]?S+,which gives improved accuracy compared with previous result.Based on 980 fb-1 integrated lumi-nosity collected by Belle,17.9k signal cases are extracted in the signal region for exper-imental data.From Dalitz-plot fit result,seven significant intermediate resonances are determined.The process of K*(1680)0 decaying into KS0? is observed and the branch-ing ratio of K*(1680)0?*KS0? to K*(1680)0?K0S?0 is measured as 0.04-0.03+0.05.The branching ratio of D0?K*(892)0? is measured as(1.44-0.15+0.12)%.The CP violation in D0?KS0?0? decay is also studied.