Transverse spin asymmetries in neutral strange particle production

[摘要] The origin of the quantum mechanical spin of the proton in terms of its constituents is not yet fully understood. The discovery that the intrinsic spin of quarks contributes only a small fraction of the total proton spin sparked a huge theoretical and experimental effort to understand the origin of the remainder. In particular the transverse spin properties of the proton remain poorly understood. Significant transverse spin asymmetries in the production of hadrons have been observed over many years, and are related to both the transverse polarisation of quarks in a transversely polarised proton and to the spin dependence of orbital motion. These asymmetries are of interest because of perturbative QCD predictions that such asymmetries should be small. Measurements of such asymmetries may yield further insights into the transverse spin structure of the proton. The Relativistic Heavy Ion Collider (RHIC) is the world's first polarised proton collider, and has been taking proton data since 2001. Polarised proton collisions at \(\sqrt{s}\) = 200 GeV taken during the 2006 RHIC run have been analysed and the transverse single and double spin asymmetries in the production of the neutral strange particles \(K^0_S\), \(\Lambda\) and \(\overline{\Lambda}\) have been measured in the transverse momentum range 0.5 < \(p_T\) < 4.0 GeV/c at \(x_F \approx\) 0. Within statistical uncertainties of a few percent the asymmetries are found to be consistent with zero.

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

[关键词] Q Science;QC Physics