PARTON DISTRIBUTIONS FOR HIGH-ENERGY COLLISIONS

Recent data from deep inelastic scattering experiments at x greater-than-or-similar-to 10(-2) are used to fix the parton distributions down to x congruent-to 10(-4) and Q2 congruent-to 0.3 GeV2. The predicted extrapolations are uniquely determined by the requirement of a valence-like structure of all parton distributions at some low resolution scale and are furthermore shown to be insensitive in the small-x region, 10(-4) less-than-or-similar-to x less-than-or-equal-to 10(-2), to the detailed experimental input at the presently accessible x > 10(-2). Simple parameterizations of the resulting parton distributions are presented in the range 10(-5) less-than-or-similar-to x < 1 and 0.3 less-than-or-similar-to Q2 less-than-or-similar-to 10(8) GeV2 as obtained from the leading- and higher-order evolution equations.