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

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

Summary of the XXVIIth Rencontres de Blois: Particle Physics and Cosmology

This writeup summarises some of the highlights from the 2015 Rencontres de Blois, with a compression ratio of about 100:1 relative to the original presentations.Comment: 22 pages, 24 figures, presented at XXVIIth Rencontres de Blois, France, 31 May - 5 June 201

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

QCD in hadron collisions

This talk examines recent progress in collider QCD and some facets of the interplay between these developments and searches for new particles and phenomena at the Tevatron and LHC.Comment: 9 pages, 4 figures, contribution to the proceedings of La Thuile 2012, the XXVI Rencontres de Physique de la Vall\'ee d'Aost

A posteriori inclusion of PDFs in NLO QCD final-state calculations

Any NLO calculation of a QCD final-state observable involves Monte Carlo integration over a large number of events. For DIS and hadron colliders this must usually be repeated for each new PDF set, making it impractical to consider many `error' PDF sets, or carry out PDF fits. Here we discuss ``a posteriori'' inclusion of PDFs, whereby the Monte Carlo run calculates a grid (in x and Q) of cross section weights that can subsequently be combined with an arbitrary PDF. The procedure is numerically equivalent to using an interpolated form of the PDF. The main novelty relative to prior work is the use of higher-order interpolation, which substantially improves the tradeoff between accuracy and memory use. An accuracy of about 0.01% has been reached for the single inclusive cross-section in the central rapidity region |y|<0.5 for jet transverse momenta from 100 to 5000 GeV. This method should facilitate the consistent inclusion of final-state data from HERA, Tevatron and LHC in PDF fits, thus helping to increase the sensitivity of LHC to deviations from standard Model predictions.Comment: contribution to the CERN DESY workshop on "HERA and LHC

CAESAR: Computer Automated Resummations

This talk gives a brief discussion of the motivations and principles behind computer automated expert semi-analytical resummation (CAESAR) for QCD final states.Comment: 4 pages; talk presented at DIS 2004, Strbske Pleso, Slovakia, April 200