Final COMPASS results on the deuteron spin-dependent structure function $g_1^{\mathrm{d}}$ and the Bjorken sum rule

Abstract

Final results are presented from the inclusive measurement of deep-inelastic polarised-muon scattering on longitudinally polarised deuterons using a ${}^6$LiD target. The data were taken at $160\mathrm{GeV}$ beam energy and the results are shown for the kinematic range $1(\mathrm{GeV}/c{)}^2<Q^2<100(\mathrm{GeV}/c{)}^2$ in photon virtuality, $0.004<x<0.7$ in the Bjorken scaling variable and $W>4\mathrm{GeV}/c^2$ in the mass of the hadronic final state. The deuteron double-spin asymmetry $A_1^{\mathrm{d}}$ and the deuteron longitudinal-spin structure function $g_1^{\mathrm{d}}$ are presented in bins of $x$ and $Q^2$. Towards lowest accessible values of $x$, $g_1^{\mathrm{d}}$ decreases and becomes consistent with zero within uncertainties. The presented final $g_1^{\mathrm{d}}$ values together with the recently published final $g_1^{\mathrm{p}}$ values of COMPASS are used to again evaluate the Bjorken sum rule and perform the QCD fit to the $g_1$ world data at next-to-leading order of the strong coupling constant. In both cases, changes in central values of the resulting numbers are well within statistical uncertainties. The flavour-singlet axial charge $a_0$, {which is identified in the $\overline{\mathrm{MS}}$ renormalisation scheme with the total contribution of quark helicities to the nucleon spin}, is extracted from only the COMPASS deuteron data with negligible extrapolation uncertainty: $a_0(Q^2=3(\mathrm{GeV}/c{)}^2)=0.32\pm 0.02_{\mathrm{stat}}\pm 0.04_{\mathrm{syst}}\pm 0.05_{\mathrm{evol}}$. Together with the recent results on the proton spin structure function $g_1^{\mathrm{p}}$, the results on $g_1^{\mathrm{d}}$ constitute the COMPASS legacy on the measurements of $g_1$ through inclusive spin-dependent deep inelastic scattering.

16 pages, 6 figures

References in corpus (18)

• The COMPASS Experiment at CERN
• The Spin Structure of the Nucleon
• Measurements of the Proton and Deuteron Spin Structure Functions g1 and g2
• Precise determination of the spin structure function ${\mathbf{g}}_1$ of the proton, deuteron and neutron
• The Deuteron Spin-dependent Structure Function g1d and its First Moment
• A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target
• The Calculation of the Two-Loop Spin Splitting Functions $P_{ij}^{(1)}(x)$
• Measurement of the Deuteron Spin Structure Function g_1^d(x) for 1 (GeV/c)^2 < Q^2 < 40 (GeV/c)^2
• Determination of the Bjorken Sum and Strong Coupling from Polarized Structure Functions
• The Spin-dependent Structure Function of the Proton g_1^p and a Test of the Bjorken Sum Rule
• Polarized Parton Distribution Functions in the Nucleon
• Measurement of the $x$- and $Q^2$-Dependence of the Asymmetry $A_1$ on the Nucleon
• Measurements of R=sigma_L/sigma_T for 0.03<x<0.1 and Fit to World Data
• The Spin Structure Function $g_1^{\mathrm{p}}$ of the Proton and a Test of the Bjorken Sum Rule
• On the Behaviour of Non--Singlet Structure Functions at Small $x$
• First Measurement of the Tensor Structure Function $b_1$ of the Deuteron
• Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2
• The Ellis-Jaffe Sum Rule: The Estimates of the Next-to-Next-to- Leading-Order QCD Corrections

Cited by in corpus (26)

• The Spin Structure of the Nucleon
• First analysis of world polarized DIS data with small-$x$ helicity evolution
• Measurement of the Bjorken Sum at very low $Q^2$
• Analytical approaches to the determination of spin-dependent parton distribution functions at NNLO approximation
• Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at $\sqrt{s}=200$ GeV
• Polarized electron-deuteron deep-inelastic scattering with spectator nucleon tagging
• Study of spin-dependent structure functions of ${}^3\mathrm{He}$ and ${}^3\mathrm{H}$ at NNLO approximation and corresponding nuclear corrections
• Bjorken sum rule with hyperasymptotic precision
• Polarised parton distribution functions and proton spin
• $O({\alpha }_s^2$) Polarized Heavy Flavor Corrections}to Deep-Inelastic Scattering at $Q^2\gg m^2$
• Future tests of parton distributions
• Optimized determination of the polarized Bjorken sum rule in pQCD
• Global analysis of polarized DIS & SIDIS data with improved small-$x$ helicity evolution
• Polarized GPDs and structure functions of $\rho$ meson
• Evaluation of Bjorken polarised sum rule with a renormalon-motivated approach
• Impact of recent COMPASS data on polarized parton distributions and structure functions
• Sensitivity of strange quark polarization to flavor SU(3) symmetry breaking
• Investigations on the flavor-dependent axial charges of the octet baryons
• Recent data analysis to revisit the spin structure function of nucleon in Laplace space
• An analysis of polarized parton distribution functions with nonlinear QCD evolution equations
• Deciphering Twist-3 Chiral-Even GPDs in the Light-Front Quark-Diquark Model
• Measurement of the nucleon spin structure functions for 0.01<$Q^2$<1 GeV${}^2$ using CLAS
• Probing nucleon spin structure in deep-inelastic scattering, proton-proton collisions and Drell-Yan processes
• The quark orbital angular momentum of ground state octet baryons
• Toward Precision Helicity PDFs from Global DIS and SIDIS Fits with Projected EIC Measurements
• Nucleon spin structure functions, considering target mass correction and higher twist effects at the NNLO accuracy and their transverse momentum dependence