First Measurement of Charged Current Cross Sections with Longitudinally Polarised Positrons at HERA
The analysis presented in this thesis concerns the $e^{+}p$ deep inelastic\ncharged current scattering cross sections measured with the H1 detector at HERA.\nThe analysed data were taken in the years 2003-04 at a centre-of-mass energy\n$\\sqrt{s} = 319 \\ GeV $ and comprise two periods of\npositron beams with positive and negative longitudinal polarisation, corresponding\nto an integrated luminosity of 26.9 $pb^{-1}$ and 20.7 $pb^{-1}$, respectively.\nThe cross sections are measured in a kinematic region of\nfour-momentum transfer squared $Q^2 \\geqslant 300 \\ GeV^2$ and inelasticity\n$y \\leqslant 0.9$. \\\\\nFrom the analysed data the polarisation dependence of the total charged current\ncross section is determined for the first time at high $Q^2$. The results are\ncompared with predictions of the Standard Model and found to be in agreement,\ni.e. possible contributions from non-standard right-handed currents are\nconsistent with zero.