The Spin Structure of the Proton at Low Q2: A Measurement of the Structure Function g2p

Abstract

Quantum Chromodynamics (QCD) is the fundamental theory that describes the strong interaction. It has been verified in the asymptotically free region. However, the non-perturbative confinement of quarks within the nucleon is still not well understood within QCD. In the non-perturbative regime, low-energy effective field theories such as chiral perturbation theory provide predictions for the spin structure functions. The neutron spin structure functions, g1n and g2n, and the proton spin structure function, g1p, have been measured over a wide kinematic range and compared with the theoretical predictions. However, the proton spin structure function, g2p, remains largely unmeasured. The E08-027 collaboration successfully performed the first measurement of the inclusive electron-proton scattering in the Q2 range 0.02-0.2 GeV2. The results allow us to obtain the generalized spin polarizabilities and test the Burkhardtt-Cottingham (BC) sum rule. Chiral perturbation theory is expected to work in this kinematic range and this measurement of spin polarizabilities will give a benchmark test to chiral perturbation theory calculations. This thesis will discuss preliminary results from the E08-027 data analysis.