Measurement Of CP Even Fraction And Strong Phase Difference In D~0 And (?)~0 Decay To ?~+?~-?~+?~-at BES?

Since the discovery of Higgs at 2012,particle physics are mainly categorized into two types:precisie test on Standard Model(SM)and direct search for new physics.As a e+e-collider running at ?-charm energy region,BEPC?/BES? has run successfully for more than 10 years,the very well detector performance and the large data sample with high quality provide an excellent platform for high energy physics study.In this thesis,two studies are done using BES?'s data,as shown following.As a basic concept of SM,the unitarity of the CKM matrix can be presented as a closed triangle.The measurement of the three angles of the unitarity triangle is one major approach to test SM precisely.As the most un-precise angle,?'s measurement needs external input of D decay information,such as strong phase difference,CP even fraction,or decay ratio.Along with more and more data collected on B factory,the precision measurement of ? needs more precise D decay information.Using 2.93 fb-1 of(?)=3.773 GeV data collected at BES?,we measured the CP even fraction and strong phase difference in D-+4?± process.The measured results have a higher precision than previous results measured by CLEO-c,which provide an important input for ? measurement by B factory through processes like B±?DK±,and then play an important role in precise measurement of the CKM matrix and test on SM.As one of famous unknown puzzles,dark matter can't be explained by SM.Al-though many significant observations from astronomy,there is neither no direct ob-servation nor clear understanding of dark matter.Some new physics models,such as Next-to-Minimal Supersymmetric Standard Model(NMSSM),have predicted the quarkonium vector could decay to an A0 radiatively,which A0 could decay to two neu-tralino ?0.And the ?0 is a candidate of dark matter,therefore,the dark matter could be searched through quarkonium radiatively decays.Using the 448.1 million ?(3686)data set collected on BESIII,88.48 million J/? events are reconstructed,and J/? ra-diatively decays to dark matter are searched.Without any significant signal observed,using frequentist CLs method,the branching ratio's upper limits at 90%confident level are calculated.The value corresponding to zero A0 mass is 7.0 × 10-7,which is around 6 times better than previous results by CLEO-c.Furthermore,using the result of this analysis,the two parameters of NMSSM,cos ?A and tan ? are constrained.This thesis also introduced the STCF collider experiment,which is under R&D stage.As a possible next generation e+e-collider,the luminosity of STCF is improved more than 50 times,which means much more data at ?-charm energy region.This thesis introduced the development of fast simulation package,which is necessary for STCF physics simulation group for simulation study.