Inclusive jet cross section measurement at D0

We present a new preliminary measurement of the inclusive jet cross section in pp-bar collisions based on a integrated luminosity of about 0.8 fb-1. The data were acquired using the D0 detector between 2002 and 2005. Jets are reconstructed using an iterative cone algorithm with radius R_cone = 0.7. The inclusive jet cross section is presented as a function of transverse jet momentum and rapidity. Predictions from perturbative QCD in next-to-leading order, plus threshold corrections in 2-loop accuracy describe the shape in the transverse jet momentum.Comment: 4 pages, 4 figures; proceedings of the DIS 2006 worksho

D0 QCD studies

A number of recent measurements from D0 that can be used to constrain parton distributions and tune QCD Monte Carlo models are presented. The selection includes W charge asymmetry, Z+jet event properties, dijet azimuthal decorrelations and the inclusive jet cross section.Comment: 4 pages, 4 figures; proceedings of the DIS 2006 worksho

Heavy quark jets at the LHC

We summarize measurements of b and c jet production at the LHC, which are an important signature and background for decays of massive particles such as H-to-b-bbar. These include measurements of the inclusive and dijet production of heavy quark jets, b and c jets produced in association with vector bosons Z and W, and decays of boosted Z bosons into pairs of b-bbar. The current status of b tagging and b jet energy scale is also reviewed. These measurements test perturbative QCD in the four and five-flavor number schemes, and provide insight into the relative importance of heavy flavor production through flavor creation, flavor excitation and gluon splitting channels. The W+c measurement provides additionally a powerful way to probe the strange quark and antiquark sea in the proton. The recent studies looking separately at production of one and two b jets find generally good agreement with theory predictions for two b-jet production, while some discrepancies are observed for singly produced b jets, particularly at large b-jet pT , where gluon splitting becomes dominant.Comment: Article submitted to the International Journal of Modern Physics A (IJMPA) as part of the special issue on the "Jet Measurements at the LHC", editor G. Dissertori. 16 pages, 27 figure

Inducing Constraint Grammars

Constraint Grammar rules are induced from corpora. A simple scheme based on local information, i.e., on lexical biases and next-neighbour contexts, extended through the use of barriers, reached 87.3 percent precision (1.12 tags/word) at 98.2 percent recall. The results compare favourably with other methods that are used for similar tasks although they are by no means as good as the results achieved using the original hand-written rules developed over several years time.Comment: 10 pages, uuencoded, gzipped PostScrip