Topological Charge Screening and the `Proton Spin' Beyond the Chiral Limit

Abstract

The theory of the `proton spin' effect proposed in our earlier papers is extended to include the chiral SU(3) symmetry breaking and flavour mixing induced by non-vanishing quark masses in QCD. The theoretical basis is the derivation of exact, unified Goldberger-Treiman (GT) relations valid beyond the chiral limit. The observed suppression in the flavour singlet axial charge $a^0(Q^2)$ is explained by an anomalously small value for the slope of the singlet current correlation function $<0|T~\pl^\m J_{\m 5}^0 ~ \pl^\n J_{\n 5}^0 |0>$, a consequence of the screening of topological charge in the QCD vacuum. Numerical predictions are obtained by evaluating the current correlation functions using QCD spectral sum rules. The results, $a^0(Q^2)=0.31\pm 0.02$ and $\int dx{g}_1^p(x,Q^2)=0.141\pm 0.005$ (at $Q^2=10 \~\GV^2$), are in good agreement with current experimental data on the polarised proton structure function $g_1^p$.

44 pages, plain TeX, 2 ps figures

References in corpus (2)

• Determination of the Bjorken Sum and Strong Coupling from Polarized Structure Functions
• Testing Target Independence of the `Proton Spin' Effect in Semi-Inclusive Deep Inelastic Scattering

Cited by in corpus (32)

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• SU(N) gauge theories at large N
• Theta dependence of SU(N) gauge theories in the presence of a topological term
• X(1835) as the Lowest Mass Pseudoscalar Glueball and Proton Spin Problem
• QCD Tests of the Puzzling Scalar Mesons
• Direct instantons, topological charge screening and QCD glueball sum rules
• The U_A(1) Problem on the Lattice with Ginsparg-Wilson Fermions
• Understanding the proton's spin structure
• The role of the chiral anomaly in polarized deeply inelastic scattering I: Finding the triangle graph inside the box diagram in Bjorken and Regge asymptotics
• Gluonia, Scalar and Hybrid Mesons in QCD
• The role of the chiral anomaly in polarized deeply inelastic scattering II: Topological screening and transitions from emergent axion-like dynamics
• Scalar Mesons in QCD
• Light scalar mesons in QCD
• eta' meson production in proton-proton collisions
• Scalar mesons and the muon anomaly
• Pseudoscalar Meson Decay Constants and Couplings, the Witten-Veneziano Formula beyond large N_c, and the Topological Susceptibility
• Axial exchange currents and nucleon spin
• Tests of the nature and of the gluon content of the σ(0.6) from D and D_{s} semileptonic decays
• Radiative ${\eta }^{\prime }$ Decays, the Topological Susceptibility and the Witten-Veneziano Mass Formula
• Reviewing the problem of the U(1) axial symmetry and the chiral transition in QCD
• Lattice determination of the topological susceptibility slope ${\chi }^{\prime }$ of $2d{\mathrm{CP}}^{N-1}$ models at large $N$
• Scalar mesons in QCD and tests of the gluon content of the sigma
• The Polarised Photon $g_1^{\gamma }$ Sum Rule at the Linear Collider and High Luminosity B Factories
• Fractional topological charge in $SU(N)$ gauge theories without dynamical quarks
• Axial and pseudoscalar current correlators and their couplings to eta and etaprime mesons
• The effects of an extra U(1) axial condensate on the radiative decay eta' --> gamma gamma at finite temperature
• The derivative of the topological susceptibility at zero momentum and an estimate of ${\eta }^{\prime }$ mass in the chiral limit
• $U(1{)}_A$ axial anomaly, ${\eta }^{\prime }$, and topological susceptibility in the holographic soft-wall model
• Gluonic effects in vector meson photoproduction at large momentum transfers
• Towards an understanding of nucleon spin structure: from hard to soft scales
• Eta-Eta' mixing and the derivative of the topological susceptibility at zero momentum transfer
• The problem of the U(1) axial symmetry and the chiral transition in QCD