Polarized Di-hadron production in lepton-nucleon collisions at the next-to-leading order of QCD

We compute the next-to-leading order QCD corrections to the spin-dependent cross section for hadron-pair photoproduction. In the first part of the Thesis the calculation is performed using largely analytical methods. We present a detailed phenomenological study of our results focussing on the $K$-factors and scale dependence of the next-to-leading order cross sections. The second part is dedicated to an alternative approach using Monte-Carlo integration techniques. We present a detailed description how this method works in practice and give phenomenological studies for the photoproduction of two hadrons. This process is relevant for the extraction of the gluon polarization in present and future spin-dependent lepton-nucleon scattering experiments

Ensemble averaging of conductance fluctuations in multiwall carbon nanotubes

Abstract. We report resistance measurements for a single multiwall carbon nanotube as a function of gate voltage and perpendicular magnetic field. The tubes were trapped onto pre-patterned Al electrodes by means of an ac electric field. Magnetoresistance traces measured for various values of the gate voltage were averaged, which corresponds to an ensemble averaging of conductance fluctuations induced by quantum interference. The ensemble averaging decreases the conductance fluctuations, while leaving the weak localization contribution to the resistance unchanged. Our data can be consistently interpreted in terms quantum transport in the presence of a weak disorder