Studies on Spin-Spin-Correlations in dileptonic top pair-events at LHC

During summer of 2008 the proton–proton-collider LHC will start its oper- ation. With a centre-of-mass engery of 14 TeV and an initial luminosity of $10^{33} cm^{-2} s^{-1}$ about $8 × 10^{6}$ top-pairs will be produced per year. Due to its short lifetime the two quarks decay before any hadronization can take place and the top-quarks can be treated as a free quarks. As effect of this, a unique possibility is the study of the undiluted top-spin. The spin information of the top is passed to the decay particles and visible as angular distributions. Because of the processes that lead to the pair-production the spins of the two tops are correlated. The high event rate allows to do precise studies of spin–spin-correlations with the CMS experiment. The present study uses the dileptonic decay channel at an integrated luminosity of $10 fb^{-1}$ . For the preparatory studies detailed event simulation and reconstruction for the CMS detector are done. Taking the expected statistical and systematic uncertainties into account a precision of 7% for the correlation measurement can be achieved.