Measurement of the high-Q"2 neutral current deep inelastic scattering cross sections with the ZEUS detector at HERA

The present thesis presents a measurement of the electron- and positron-proton neutral current deep inelastic scattering cross sections at high four-momentum transfer. The data used in these measurements were collected by the ZEUS experiment running in the HERA collider in Hamburg. The data analysed corresponds to integrated luminosities of 15.87 pb"-"1 for e"-p and 62.53 pb"-"1 for e"+p scattering, and was collected at a centre-of-mass energy of 318 GeV. The double-differential cross sections d"2#sigma#/dxdQ"2 for e"-p and e"+p were measured in the ranges of 0.005 #<=# x #<=# 0.65 and 200 GeV"2 #<=# Q"2 #<=# 30000 GeV"2. The single-differential cross sections d#sigma#/dQ"2, d#sigma#/dx and d#sigma#/dy were measured for Q"2 > 200 GeV"2. To observe the effect of the Z-boson exchange, the single-differential cross sections d#sigma#/dx and d#sigma#/dy were measured for Q"2 > 10000 GeV"2 from both e"-p and e"+p data. The measured cross sections are in good agreement with the expectations of the Standard Model. In addition to the study of the neutral current deep inelastic scattering process, the results were used to study the structure of the proton. The structure function F_2, which depends on the total quark content of the proton, was extracted using both the e"-p and the e"+p data samples. The measurements were combined to improve the accuracy of the extracted F_2 at high Q"2. The use of both data samples also permitted the extraction of the structure function xF_3, which depends on the valence-quark content of the proton. (orig.)SIGLEAvailable from TIB Hannover: RA 8919(2003-022) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman