Quantitative analysis of Geometrical Scaling in Deep Inelastic Scattering

Abstract: We analyze geometrical scaling in deep inelastic scattering using experimental data from HERA ep collider. Parallel analyses are performed for energy and Bjorken-x data binnings. In particular, value of parameter \lambda which governs x-dependence of saturation scale is found for both binnings: \lambda_En = 0.352 \pm 0.008 and \lambda_Bj = 0.302 \pm 0.004. We use the following method: \lambda_En is found as a value for which ratios \sigma^{W1}{\gamma*p}(\tau)/\sigma^{W2}{\gamma*p}(\tau) are closest to 1 (\sigma^{Wi}_{\gamma*p} is a photon-proton cross section with definite energy W_i and \tau = Q^2 x^{\lambda} is a scaling variable); \lambda_Bj is found analogously using ratios of cross sections with definite Bjorken-x variable. We show also that GS is present for x<0.2.