6533b86ffe1ef96bd12ce75f

RESEARCH PRODUCT

The spin-dependent structure function g1(x) of the deuteron from polarized deep-inelastic muon scattering

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We present a new measurement of the spin-dependent structure function $g_{1}^{\rm d}$ of the deuteron from deep inelastic scattering of 190 GeV polarized muons on polarized deuterons. The results are combined with our previous measurements of $g_{1}^{\rm d}$. A perturbative QCD evolution in next-to-leading order is used to compute $g_{1}^{\rm d}(x)$ at a constant $Q^{2}$. At $Q^{2} = 10$ GeV$^{2}$, we obtain a first moment $\Gamma_{1}^{\rm d} = \int_{0}^{1} g_{1}^{\rm d}{\rm d}x = 0.041 \pm 0.008$, a flavour-singlet axial charge of the nucleon $a_{0} = 0.30 \pm 0.08$, and an axial charge of the strange quark $a_{s} = -0.09 \pm 0.03$. Using our earlier determination of $\Gamma_{1}^{\rm p}$, we obtain $\Gamma_1^{\rm p} - \Gamma_1^{\rm n} = 0.183 \pm 0.035$ at $Q^2 = 10\,\mbox{GeV}^2$. This result is in agreement with the Bjorken sum rule which predicts $\Gamma_1^{\rm p} - \Gamma_1^{\rm n} = 0.186 \pm 0.002$ at the same $Q^2$.