Ratio of the structure functions and the color dipole model bound

Abstract

We observe that the DGLAP evolution equations at NNLO analysis predicts a ratio of the structure functions in region of small Bjorken variable x. The ratio FL(x,Q2)/F2(x,Q2) is obtained and compared with the prediction of the dipole model and HERA data. In particular we show that this ratio is lower than dipole model bound at high-Q2 values and it is higher at low-Q2 values. Then the effect of adding a higher twist term to the description of the ratio FL(x,Q2)/F2(x,Q2) for Q2<20GeV2 is investigated. Also the bounds are discussed by including charm distribution on FL/F2. We discuss, furthermore, how this ratio can be determined the proton structure function with respect to the reduced cross section at high-y values.