Momentum Fractions carried by quarks and gluons in models of proton structure functions at small x
Published on Jun 30, 2017in International Journal of Modern Physics A1.153
· DOI :10.1142/S0217751X1750107X
In this paper, we report an analysis of partial momentum fractions carried by quarks and gluons in six alternative phenomenological models of proton structure function valid in limited small x regions: xai ≤ x ≤ xbi, i = 1 to 6; the limits being determined by phenomenological range of validity in each model. Since the physics of small x is not completely understood at this point, we have considered both self-similarity-based as well as QCD-based models. The procedure by which one can determine the applicability ranges in x and Q2 of the models is presented. We find that while the self-similarity-based models with linear rise in Q2 has limited phenomenological ranges of validity, an improved version with linear rise in log Q2 has a wider phenomenological range. We then compare the partial momentum fractions in all the small x models. Our analysis implies that the role of small x sea quarks in calculating the second moments of parton distribution is minor one. We have also made a comprehensive comparison of all the phenomenological models considered to the available perturbative QCD, lattice QCD as well as Ads/QCD results.