Nonlinear evolution and parton distributions at LHC and THERA energies

We suggest a new procedure for extrapolating the parton distributions from HERA energies to higher energies at (THERA, LHC). The procedure suggested c onsists of two steps: first, we solve the nonlinear evolution equation whic h includes the higher-twist contributions, however this equation is deficie nt due to the low (log(1/x)) accuracy of our calculations. Second, we intro duce a correcting function for which we write a DGLAP type linear evolution equation. We show that this correcting function is small in the whole kine matic region and decreases at low x. The nonlinear evolution equation is so lved numerically and first estimates for the saturation scale, as well as f or the value of the gluon density at THERA and LHC energies are made. We sh ow that nonlinear effects lead to damping of the gluon density by a factor of 2-3 at x approximate to 10(-7). (C) 2001 Elsevier Science B.V. All right s reserved.