How open charm production and scaling violations probe the rightmost hard BFKL pole exchange

In 1994 Zakharov and the present authors argued that in color dipole (CD) B FKL approach to DIS excitation of open charm at moderately large Q(2) is do minated by hard BFKL exchange. In view of the rapid accumulation of the exp erimental data on small-x charm structure function of the proton F-2(c) fro m HERA, we subject the issue of dominance of the rightmost hard BFKL pole e xchange to further scrutiny. Based on CD BFKL-Regge factorization we report parameter-free predictions for the charm structure function F-2(c) and sho w that the background to the dominant rightmost hard BFKL exchange from sub leading hard BFKL and soft-pomeron exchanges is negligible small from real photo-production to DIS at Q(2) less than or similar to 50-100 GeV2. The ag reement with the experiment is good and lends strong support for the interc ept of the rightmost hard BFKL pole Delta (P) = alpha (P) - 1 = 0.4 as foun d in 1994 in the color dipole approach. We comment on the related determina tion of Delta (P) from the x-dependence of the longitudinal structure funct ion F-L(x, Q(2)) and of the scaling violation partial derivativeF(2)/partia l derivative log Q(2) taken at a suitable value of Q(2). (C) 2001 Published by Elsevier Science B.V.