Theory Seminar May 5


Abstract

Impact of the total resummation of the leading logarithms on the
small x behavior of the spin structure function g_1
Boris Ermolaev
Ioffe Phys. Tech. Inst.
Total resummation of the leading (double and single) logarithms
converts the smallx behavior of g_1 into the Regge one in contrast to
the DGLAP predictions.
Accounting for the running coupling effects allows to estimate the
intercepts of the nonsinglet and singlet components of g_1 (0.4 and 0.8
approx) and also estimate the sign of the g_1 singlet at x<<1 (negative).
Ther is a new scaling for g_1 at small x: g_1 depends on one
argument (Q^2/x^2) instead of depending on two, x and Q^2.
Contrary to the common opinion, we find that the impact of the resummation
is quite sizable for the values of x = 0.005 approx and less. DGLAP
formally does not account for those contributions but actually imitates them
through using the singular fits for the parton densities.

Directions
to Fermilab.
Keith Ellis, ellis@fnal.gov
and Ayres Freitas, afreitas@fnal.gov