Closing Talk: Qcd Moriond 2006

One of the advantages of giving the closing talk at a conference with only plenary sessions, is that a summary is certainly superfluous. I shall take full advantage of that freedom in my talk and present only a few topics. In the infinite momentum frame (IMF) a proton or nucleus is seen as a Lorentz contracted disk, and xg(x, Q 2) is the number of gluons per unit rapidity of transverse size less than 1/Q on that disk. At small x the number of gluons becomes so large that there is a saturation in the growth of the number of gluons. As a consequence of this saturation, the total virtual-photon proton scattering cross section satisfies a geometrical scaling law 1 as shown in Fig. 1, σ(x, Q 2) → σ(τ), τ = Q 2 /Q 2 s (x), Q s (x) = (x/x 0) λ , λ = 0.3. (1) Q s (x) is the x-dependent saturation scale. Recent work in this area is beginning to look in more detail at the region near and beyond the saturation boundary. 2,3 While there is geometrical scaling in the region close to the saturation