On the new COMPASS measurement of the deuteron spin-dependent structure function $g_1^d$

Abstract

Very recently, a new measurement of the deuteron spin-dependent structure function $g_1^d (x)$ was reported by the COMPASS group. A main change from the old SMC measurement is a considerable improvement of the statistical accuracy in the low $x$ region $0.004 < x < 0.03$. We point out that the new COMPASS data for $g_1^d (x)$ as well as their QCD fits for $\Delta \Sigma$ and $\Delta s + \Delta \bar{s}$ are all remarkably close to our theoretical predictions given several years ago based on the chiral quark soliton model.