Small-x Behavior of Non-singlet Spin Structure Function and Bjorken Sum Rule with pQCD Correction up to NNLO and Higher Twist Correction

Abstract

A calculation of the non-singlet part of spin dependent structure function, xg N S 1 (x, Q 2 ) and associated sum rule, the Bjorken Sum rule up to next-next-to-leading order(NNLO) is presented. We use a unified approach incorporating Regge theory and the theoretical framework of perturbative Quantum Chromodynamics. Using a Regge behaved model with Q 2 dependent intercept as the initial input, we have solved the Dokshitzer-GribovLipatov-Altarelli-Parisi (DGLAP) evolution equation up to NNLO at small-2 ) and the solutions are utilised to calculate the polarised Bjorken sum rule(BSR). We have also extracted the higher twist contribution to BSR based on a simple parametrisation. These results for both of xg2 ) and BSR, along with higher twist corrections are observed to be consistent with the available data taken from SMC, E143, HERMES, COM-PASS and JLab experiments. In addition, our results are also compared with that of other theoretical and phenomenological analysis based on different models and a very good agreement is also observed in this regard. Further a very good consistency between our calculated results and theoretical QCD predictions of BSR is also achieved.

Nucleon spin structure functions at NNLO in the presence of target mass corrections and higher twist effects

“…In the light-cone operator-product expansion (OPE), the leading-twist (twist τ = 2) contributions correspond to scattering off asymptotically free partons, while the higher-twist contributions emerge due to multiparton correlations. The leading-twist spin-dependent proton and neutron structure functions, g p,n 1 (x, Q 2 ) at NNLO, can be expressed as a linear combination of polarized parton densities and coefficient functions as [13,21,22]…”

Nonlinear Effects in Gluon Distribution Predicted by GLR-MQ Evolution Equation at Next-to-leading Order in LHC Data

“…The results are then adjusted to fit the experimental data (mainly at small-x) available for the proton structure function F 2 (x, Q 2 ) measured in DIS, over a large range of values of x and Q 2 by adjusting the parameters in the initial distributions. With much phenomenological success approximate solutions of the linear DGLAP evolution equations have been reported in recent years [21][22][23][24][25][26][27][28][29][30].…”