A resummation of large sub-leading corrections at small x

Abstract

The NLL corrections to the BFKL kernel are known to be very large, to the extent that even for small values of alpha_s, they lead to physical cross sections which are not positive definite. It is shown in the context of a toy model, that such pathological behaviour is an artifact of the truncation at NLL order, and is associated in particular with double transverse logarithms. These are resummed in a manner consistent with the full NLL kernel, and are shown to change its properties quite considerably.

19 pages LaTeX, 5 figures, includes JHEP.cls and cite.sty. Version 2 additionally includes an appendix, numerous clarifications, correction of typos and extra references