Nucleon Spin Physics

Abstract

The quark-gluon dynamics inside a nucleon is easily accessible system around us to study the low energy phenomena of quantum chromodynamics. For the purpose of understanding the internal dynamics of the nucleon, a lot of high energy experiments have been performed so far. As a consequence, we have gained knowledge that unpolarized parton distribution function well describes the internal structure of the nucleon with regarding to results of spin-independent measurement. However, the spin-dependent interactions are also inevitable feature to understand quantum chromodynamics. For the exclusive investigation of quantum chromodynamics, the spin-dependent dynamics inside a polarized nucleon is also a key topic to be revealed. For this purpose, polarized parton distribution functions are principal physics quantities to be studied. Especially, whereas the polarized parton distributions for quarks have been revealed with enough precision to understand their contribution to the nucleon spin 1/2, the distribution function for gluon has not been enough understood yet. In this work, the gluon polarization is investigated by measuring heavy flavor production in polarized proton-proton collisions. For the introduction of this study, we explain the spin physics in the nucleon and the measurement of the polarized parton distribution functions through experiments in this chapter. And in the last section, we introduce the measurement of the gluon polarization with the heavy flavor production.