Theory Seminar May 5
Impact of the total resummation of the leading logarithms on the
small x behavior of the spin structure function g_1
Ioffe Phys. Tech. Inst.
Total resummation of the leading (double and single) logarithms
converts the small-x 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 non-singlet 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.
Keith Ellis, email@example.com
and Ayres Freitas, firstname.lastname@example.org