Measurements of the Neutral Current ep Cross Sections Using Longitudinally Polarised Lepton Beams at HERAII

This thesis presents inclusive $e^\pm p$ single and double
differential cross sections for neutral current deep inelastic
scattering measured as functions of the four-momentum transfer
squared $Q^2$ and the Bjorken variable $x$ in interactions of
longitudinally polarised leptons with unpolarised protons using the
H1 detector at HERA~II. An overview of the phenomenology of deep
inelastic scattering is given and the experimental apparatus as
well as the measurement and analysis procedures are described. The
analysis is based on $e^+p$ data taken in 2003-04 and $e^-p$ data
taken in 2005 at a centre-of-mass energy of $\sqrt s = 318$~GeV,
with integrated luminosities of 47.6~pb$^{-1}$ and 98.4~pb$^{-1}$
for the $e^+ p$ and $e^- p$ samples, respectively. The cross
sections are measured in the range of $200 < Q^2 <
20\,000$~GeV$^2$ and $0.0032