Amplitude Analysis Of D_s~+?K_S~0?~+?~0 And Absolute Branching Fraction Measurement Of D_s~+?K_S~0?~+?~0 And D_s~+??~+?~-?~+?~0 At BES?

The study of the singly Cabibbo-suppressed(SCS)DS+?K0?+?0 decay can help us accurately understand the proportion and branch ratio of the intermediate process and test the SU(3)symmetry of the standard model and its breaking effect,which is helpful to test the resonance effect of the pole model of the annihilation contribution,and provide the amplitude and phase between the contributions of different topological types in this process Strong phase information.DS+?K0?+?0 has a large BF at the order of 10-2.This decay is,therefore.usually suited as a reference channel for other decays of the Ds meson and used as normalization for decay chains involving charm quarks.An accurate knowledge of its substructure is important to reduce systematic uncertainties in analyses using this channel.In addition,Utilizing the data set corresponding to an integrated luminosity of 6.32 fb-1 recorded at a center-of-mass energy of 4.18 to 4.23 GeV with the BESIII detector,we report the amplitude analysis and branching fraction measurement of single-Cabibbo-suppressed DS+?KS0?+?0 decay.In the amplitude analysis,we used the double-tag selection to select cases of data,and obtained 609 events.After the amplitude of intermediate process is constructed by covariant tensor analysis,we construct the likelihood function of signal and background simultaneously by maximum likelihood method,and fit the data to determine the ratio of different intermediate decay processes:DS+?KS0?+:(50.25±7.15±3.86)%,DS+?KS0?(1450)+:(20.38±4.30±4.82)%,DS+?K*(892)0?+:(8.17±2.63±0.93)%,DS+?K*(1410)?+:(3.63±1.63±0.51)%,DS+?K*(892)+?0:(4.63±1.42±0.44)%?In the absolute branching fraction measurement,we use the same tag mode as in the wave analysis(the selection method is different)to select the data and MC samples,and by fitting the data,we get 547 signals.Using the amplitude analysis results,we generated the new Generic MC,and obtained the double tag selection efficiency.Finally,after deducting the influence of the background,we accurately measured the branching fraction result:B(DS+?KS0?+?0)=(5.20±0.36(stat)±0.16(syst))×10-3.The DS+??+?-?+?0 decay is the major peaking background of DS+?KS0?+?0.so we measure its BF to have a better estimation of peaking background subtraction.The branching fraction of DS+??+?-?+?0 is determined to be B(DS+??+?-?+?0)=(1.38±0.07(stat)±0.05(sys))%.