WHERE ARE THE BFKL POMERON and SHADOWING CORRECTIONS IN DIS ?

In this talk, I will argue that the HERA experimental data show that the typical parameter (κ) responsible for the value of the shadowing corrections (SC) in DIS is so large that the BFKL Pomeron is hidden under SC. The SC turn out to be large enough but mostly for the gluon structure function which is not well determined by the available experimental data and by the current theoretical procedure. In this talk I am going to answer two questions: Q1: Where is the BFKL [2] Pomeron? Q2: Where are shadowing corrections (SC)? Actually, the answers have been presented in our paper [1], but here I will discuss them in more details. First, let me explain why it is reasonable to ask such questions. Indeed, at first sight, the situation looks very transparent, namely, the HERA data can be described by means of the usual DGLAP [3] evolution equations without any other ingredients such as the BFKL Pomeron and / or SC ( see any of plenary talks during the past three years). My personal opinion is that this fact brought more questions than answers since we need to show ( to justify theoretically our approach) that the corrections due to the BFKL dynamics and/or due to the SC are negligible small at least at the HERA kinematic region. If it is not so ( as I will show below) the DGLAP approach is not better or worse than any other model developed to describe the experimental data. The main goal of this talk is to show that the experimental data from HERA confirm that both the BFKL contribution and the SC should be rather large in the HERA kinematic region. Actually, everything that I want to tell is given in Fig.1, but I need to explain what are plotted in this figure. 1. < γ >= 1 2 and< γ >= 1. Let me recall a standard procedure of solving of the DGLAP evolution equations. The first step: we introduce moments of the structure function, namely, xG(x,Q) = 1 2πi ∫ C e M(ω,Q) dω, where contour C is located to the right of all singularities of moment M(ω,Q). The second step: we find the solution to the DGLAP equation for moment dM(ω,Q) d lnQ2 = γ(ω)M(ω,Q) . (1) The solution is M(ω,Q) = M(ω,Q0) · e γ(ω) ln(Q/Q 0 ) . (2) Here M(ω,Q0) is the nonperturbative input which should be taken from experimental data or from “soft” phenomenology ( model). The third step: we find the solution for the parton structure function using the inverse transform, namely: xG(x,Q) = ∫ C dω 2πi e ln(1/x) + γ(ω) ln(Q /Q 0 M(ω,Q0) . (3)