A Search for Rare Decay D0 --> mu+mu - High Energy Physics UPRM

i4.3 Data Selection 55hadron identification) to separate kaons from muons also, since pions and muons behavealmost identically in the Čerenkov system. The name given for this variable €¡¯d is .ii. Inner Muons. For the Inner Muon System (IMU) the algorithm begins byverifying if the candidate trajectories to be muons leave signal in the five PWC chambers.The trajectories are projected into the IMU planes and associated hits are identified bylooking within a circle around the projection .In the IMU system there are six MH planes.There must be four hits in theseplanes. We can proceed to calculate ] ^ which gives us the trajectory compatibility withthe MH hits. There are two other things that are taken into consideration when we do thiscalculation. These are the multiple Coulomb scattering that occurs inside the steel filtersand the granularity of the scintillator paddles.Lastly, an isolation variable is calculated which corresponds to the largest CL for anyother trajectory to have caused the same MH hits.Because there are steel filters in the IMU that can stop muons with low momentum,the number of required planes is reduced to two from the original number of four forcandidates with a momentum less than “•”—– 10 . This will increase the efficiency at lowmomentum.The efficiency for the muon identification algorithm is over 98% for momentumabove 10 “•”—– while misidentification is of the order of 0.5%. In-flight b d q4;decayscandidate to the misidentification rate. For this decay the pion and muon direction of flightare very closely matched.