Book Synopsis Recent Developments in Nucleon Spin Structure with Focus on H_{1L}^{\perp} and Pretzelosity H_{1T}^\perp by :
Download or read book Recent Developments in Nucleon Spin Structure with Focus on H_{1L}^{\perp} and Pretzelosity H_{1T}^\perp written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The leading twist transverse momentum dependent parton distribution functions h_{1L}^{\perp} and h_{1T}^\perp, which is sometimes called "pretzelosity," are studied. For h_{1L}^{\perp} we consider a "Wandzura-Wilczek-type" approximation, which follows from QCD equations of motion upon the neglect of pure twist-3 terms and allows to express it in terms of transversity. On the basis of available data from HERMES we test the practical usefulness of this approximation and discuss how it can be further tested by future CLAS and COMPASS data. We review the theoretical properties of retzelosity and observe an interesting relation valid in a large class of relativistic models: The difference between helicity and transversity distributions, which is often said to be a 'measure of relativistic effects' in the nucleon, is nothing but the transverse moment of pretzelosity. We discuss preliminary deuteron target data from COMPASS on the single spin asymmetry (SSA) in semi-incl.
