Investigations On Associated Production Of Gravitons And Top Quark Pair At LHC

The ADD model proposed as a possible solution to the hierarchy problem,is characterized by its prediction of Large Extra Dimension(LED)that there are extra compact dimensions of space,which is probably macroscopically large and accessible to gravity but not to ordinary matter.This thesis studies the Kaluza-Klein(KK)graviton production in the large extra dimension model via the associated production of top quark pair plus missing transverse momentum signatures at the LHC.Then this thesis investigates the process PP→t(?)Gn.The integrated cross sections and the differential cross section of this process are presented in the LED model.We find that the Leading Order(LO)result is significant enough that this channel has observable effects in the LHC experiments.When the fundamental energy scale MD is 2.3 TeV,the cross section of this process only reaches a few fb,or less as Md goes higher at the LHC with (?)= 6,7,13,14 TeV.