Neutron spin-dependent structure function, Bjorken sum rule, and first evidence for singlet contribution at low $x$

Abstract

We perform the isospin decomposition of proton and neutron SLAC data for moderately low $x$ in the region $0.01\le x\le 0.1$. The isovector part is well described by a power behaviour $x^{\alpha }$, where $\alpha$ does not correspond to the intercept of single $a_1$ Regge trajectory, as expected. However, the observed power leads to the validity of Bjorken sum rule and it is consistent with the power extracted from all previous data using NLO evolution. At the same time, the isoscalar part behaviour may be interpreted as a partial cancellation between a positive non-singlet contribution and a strongly negative singlet one. Further experimental consequences are mentioned.

LATEX, 11 pages, 2 figures available from the authors; Submitted to PRD

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• Nonlinear effects in gluon distribution predicted by GLR-MQ evolution equation at next-to-leading order in LHC data
• DIS structure functions and the double-spin asymmetry in ${\rho }^0$ electroproduction within a Regge approach
• Spin constraints on Regge predictions and perturbative evolution in high energy collisions
• Small-x analysis on the effect of gluon recombinations inside hadrons in light of the GLR-MQ-ZRS equation
• Studies on gluon evolution and geometrical scaling in kinematic constrained unitarized BFKL equation: application to high-precision HERA DIS data
• Small-x behavior of non-singlet spin structure function and Bjorken sum rule with pQCD correction up to NNLO and Higher twist correction