Hard processes

A phenomenological solution small x to the longitudinal structure function dynamical behavior

“…In this limit, the gluon distribution will become large, so its contribution to the evolution of the parton distribution becomes dominant. Therefore the gluon distribution has a rapid rise behavior small x, that is xg(x, Q 2 ) = f g x −λ , where λ is corresponding to the hard-Pomeron intercept [30][31][32][33]62]. Exploiting the small-x asymptotic behavior for the gluon distribution and charm structure functions to the evolution equations of the gluonic longitudinal structure function and charm longitudinal structure function respectively (Eqs.23, 27), evolution of the longitudinal structure function at small-x can be found as…”

“…In Figs.1-3, we present the small x behavior of the F L structure function according to the evolution equation (28) (heavy + gluonic) of longitudinal structure function with results of DL [30][31][32][33]62] and CD models [63]. In the right hand side, F…”

“…1−z and µ is the mass factorization scale, which has been put equal to the renormalization scales µ 2 = 4m [30][31][32][33]62] and CD [63] models respectively. right: The total FL compared with kT factorization [64] and H1 data [54] with total error.…”

“…In the phenomenological analysis of the high energy behavior of hadronic as well as photoproduction total cross section, the value of the intercept is determined as α sof t ≈1.08 (as this is the effective soft Pomeron) [30]. In DIS, a second hard-Pomeron must be added with a larger intercept α hp ≈1.4 [31][32][33][34][35] and recently decreases to the value 1.317 where estimated directly from the data on the proton unpolrized structure function [36]. It is tempting, however, to explore the possibility of obtaining approximate analytic solutions of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) [37][38][39] equations themselves in the restricted domain of small-x at least.…”

Parton Distributions

“…There is also work on connecting the partons to alternative approaches at small x, e.g. dipole models 45 , and pomerons 46 . These approaches can suggest improvements to the fits and changes in predictions, e.g.…”