Search for Drell Yan in √s=41.6 GeV p-N collisions at HERA-b [Elektronische Ressource] / presented by Jens Kessler

Dissertationsubmitted to theCombined Faculties for the Natural Sciences and forMathematicsof the Ruperto-Carola University of Heidelberg, Germanyfor the degree ofDoctor of Natural Sciencespresented byDiplom-Physicist Jens Kesslerborn in Dillingen/SaarOral examination: 31.10.2007Search for Drell Yan√in s =41.6 GeV p-N Collisionsat HERA-bReferees: Prof. Dr. Franz EiseleProf. Dr. Karl-Tasso Kn¨opfleAbstractIn this thesis, the data taken with the HERA-b detector in the running pe-riod 2002/2003 is used to measure the cross section of the Drell Yan process+ −qq¯ → l l , where quark and antiquark annihilate and produce a lepton pair.HERA-b, a fixed target spectrometer, is one of the four experiments at the stor-ageringHERAatDESY.Itusestheprotonbeamtoproducecollisionswithwiretargets of different materials.The main challenge of the thesis is to extract a Drell Yan signal from the datasetwithout loosing too many events and to find a suitable background simulationwhich can be subtracted from the kinematical distributions. For this purpose,a Single Track Monte Carlo is generated to calculate event weights, which areapplied to the likesign dataset. This procedure is necessary since the detectoracceptance of HERA-b is dependant on the charges of the leptons.After background subtraction and acceptance and luminosity corrections, differ-ential cross sections of the Drell Yan process are plotted, for the first time in thenegative x regime.