Fall and rise of the gluon splitting function

This talk reviews some recent results on the NLL resummed small-x gluon splitting function, as determined including renormalisation-group improvements. It also discusses the observation that the LO, NLO, NNLO, etc. hierarchy for the gluon splitting function breaks down not when (alpha_s log 1/x) is of order one but rather for (alpha_s log^2 1/x) of order one.Comment: 7 pages, 3 figures; Talk presented at DIS 2004, Strbske Pleso, Slovakia, April 2004, and at the Eighth Workshop on Non-Perturbative Quantum Chromodynamics, Paris, France, June 200

The status of NLL BFKL

This talk summarises the current status of the NLL corrections to BFKL physics and discusses the question of small-x factorisation.Comment: 4 pages, 2 figures. Uses moriond.sty (included). Talk presented at the XXXVth Rencontres de Moriond, QCD and High Energy Hadronic Interactions, Les Arcs, France, March 18-25, 200

Recent developments in perturbative QCD

A brief overview of some recently active topics in perturbative QCD, including: string-inspired recursion techniques at tree level; recursion approaches and automation of standard techniques for 1-loop calculations; the status of NNLO jet calculations; and non-trivial structures that appear in higher-order calculations.Comment: 9 pages, 1 figure. Invited talk at the XIV International Workshop on Deep Inelastic Scattering (DIS 2006), April 2006, Tsukuba, Japa

Moriond 2009, QCD and High Energy Interactions: Theory Summary

These proceedings provide a brief summary of the theoretical topics that were covered at Moriond QCD 2009, including non-perturbative QCD, perturbative QCD at colliders, a small component of physics beyond the standard model and heavy-ion collisions.Comment: 13 pages, 7 figures; v2 adds a reference; v3 includes small changes to tex

A Practical Seedless Infrared Safe Cone Algorithm

This writeup highlights the infrared unsafety of the "midpoint" cone jet-algorithm and provides a brief overview of why this is a serious issue. It then shows how one can build a safe (seedless) cone algorithm and discusses the potential impact on measurements.Comment: 4 pages, 4 figures. Talk presented at the XLII Rencontres de Moriond, QCD and Hadronic Interactions, La Thuile, March 200

A resummation of large sub-leading corrections at small x

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