Measurement of single transverse spin asymmetry via single hadrons and di-hadron correlations in the 200GeV p + p collision in the PHENIX experiment at RHIC

摘要

The spin structure of the proton has been revealed to be extremely complex. The proton spin is composed of the spins and the orbital angular momenta of quarks and gluons in the proton. The first results from polarized deep inelastic scattering (pDIS) experiments in the late 1980s and early 1990s revealed that quarks do not carry a significant fraction of the proton\u27s spin. The recent global analysis on gluon spin including RHIC results showed that gluons have a very small contribution on the spin of proton. Therefore, it is extremely important for physicists understanding the contribution from the orbital angular momenta of quarks and gluons. However, it is very difficult for the current experiments measuring the orbital angular momentum directly and accurately. The Sivers-type single transverse spin asymmetry provides us a window to study the orbital angular momentum.In this thesis, results for the single transverse spin asymmetry of forward charged hadrons in polarized proton collisions measured with the PHENIX detector are presented.A predicted sizable asymmetry has been observed which is consistent with the results from other experiments. A correlation between neutral pions and charged hadrons measured in the central region of the PHENIX detector has been used to extract the single transverse spin asymmetry due to the Sivers effect. The Sivers effect describes the relation of the proton\u27s spin and its intrinsic transverse momentum. The latter one has been thought to originate from the orbital angular momentum of proton.