Speaker
Description
I present the renormalization group improved collinear resummation of the
photon-gluon impact factors. We construct the resummed cross section for
virtual photon-photon (𝛾∗𝛾∗) scattering
which incorporates the impact factors and BFKL gluon Green’s function up
to the next-to-leading logarithmic accuracy in energy. The impact factors
include important kinematical effects which
are responsible for the most singular poles in Mellin space at
next-to-leading order. Further conditions on the resummed cross section
are obtained by requiring the consistency with the
collinear limits. Our analysis is consistent with previous impact factor
calculations at NLO, apart from a new term proportional to C_F that we
find for the longitudinal polarization. Finally, we
use the resummed cross section to compare with the LEP data on the
𝛾∗𝛾∗ cross section and with previous calculations. The resummed result
is lower than the leading logarithmic approximation
but higher than the pure next-to-leading one, and is consistent with the
experimental data.
