Helicity Amplitude Analysis Of ?(3686)??~-(?)~+ At BES?

By studying the production and decay process of hadrons,we can measure the properties of hadrons,such as spin,parity and polarization properties,which is very helpful to understand the internal structure of hadrons and provides an important ex-perimental results for the theoretical QCD study.In this thesis,we analyze 448×106?(3686)events collected with the BESIII de-tector at the BEPCII electron-positron collider.The helicity amplitudes of ?(3686)??-?+,?-?K-??K-p?-,?+?K+??K+p?+and the decay parameter?? of ??K? are measured for the first time.The analysis result favors ?-has a spin of 3/2 over a spin of 1/2 with a significance of 14.2?:With the measurement result of J?=3/2,the helicity amplitudes are measured to be:h1=0.30±0.11±0.04,?1=0.69±0.41±0.13(A1/2,1/2/A1/2,-1/2=h1ei?1);h3=0.26±0.05±0.02,?3=2.60±0.16±0.08(A3/2,1/2/A1/2,-1/2=h3ei?3);h4=0.51±0.03±0.01,?4=0.34±0.80±0.31(A3/2,3/2/A1/2,-1/2=h4ei?4).At the same time,the decay parameter of ?-K? is measured to be ??-=-??+=4.29±0.45±0.23.The measured value of ??-tells that the D-wave plays a leading role in the process of ??K?,which is different from theoretical prediction that P-wave plays a leading role.The above measurement results have another set of pos-sible solutions,but only ?1 and ?4 are significantly different,the values of the other parameters are very similar:h1=0.31±0.10±0.04,?1=2.38±0.37±0.14;h3=0.27±0.05±0.02,?3=2.57±0.16±0.05;h4=0.51±0.03±0.01,?4=1.37±0.68±0.18;??-=-??+=4.15±0.44±0.20.The decay parameter ??,is calculated as ??=0.24±0.10.The branching fraction of ?(3686)??-?+ is measured by a single-tag method of ?-/?+ to be:B(?(3686)??-?+)=(5.85±0.12±0.24)×10-5,where the first uncertainty is statistical uncertainty,and the second is systematic uncertainty.Com pared with the previously published result,the relative uncertainty of the measurement result is reduced from 8.2%to 4.6%.