Semi-inclusive Lambda electroproduction in the target fragmentation region at CLAS

[摘要] Studies into the spin structure of the proton have been an active area of research after the EMC experiment and others found that only 30% of the total proton spin is carried by the valence quarks. Hadron production in Semi-Inclusive Deep Inelastic Scattering (SIDIS) is one way to study this phenomenon and is the focus of this thesis, whichdescribes the measurement of the polarisation of theLambda. Hadron production is generally examined in the Current Fragmentation Region (CFR), where the detected hadronoriginates from the struck quark, in terms of parton distribution and fragmentation functions. Conversely in the Target Fragmentation Region (TFR), the hadron is produced in the fragmentation of the target remnants. In this region the process is described by Fracture Functions which represent the joint probability of producing the final hadron from the target remnants when a parton of the target nucleon is struck by the virtual photon. We propose to aid in the understanding of these functions by extracting the transferred polarisation of Lambda in the SIDIS electroproduction of the hadron from a proton target: ep -> Lambda e' X . In this work, data recorded with the CLAS detector system at Thomas Jefferson National Laboratory during the e1f experimental run with a longitudinally polarised beam on an unpolarised target were analysed. The polarisation of the Lambda has been extracted by using the Maximum Likelihood Extraction (MLE) and Beam Spin Asymmetry (BSA) methods.

[发布机构] University:University of Glasgow;Department:School of Physics and Astronomy

[关键词] QC Physics