Precision measurements of g 1 of the proton and of the deuteron with 6 GeV electrons

Le résumé fourni par la source

The inclusive polarized structure functions of the proton and deuteron, ${g}_{1}^{p}$ and ${g}_{1}^{d}$, were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at laboratory angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual deep inelastic region kinematics, ${Q}^{2}>1$ ${\mathrm{GeV}}^{2}$ and the final-state invariant mass $W>2$ GeV, the ratio of polarized to unpolarized structure functions ${g}_{1}/{F}_{1}$ is found to be nearly independent of ${Q}^{2}$ at fixed $x$. Significant resonant structure is apparent at values of $W$ up to 2.3 GeV. In the framework of perturbative quantum chromodynamics, the high-$W$ results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions.

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