A very important new theoretical study appeared yesterday in the hep-ph preprint arxiv.
Titled "Precise Predictions on W+4 Jet Production at the Large Hadron Collider", it is signed by a strong team of theorists: C. Berger, Z. Bern, L. Dixon, F. Febres Cordero, D. Forde, T. Gleisberg, H. Ita, D. Kosover, and D. Maitre. I will try to summarize its importance for the physics of the Large Hadron Collider in accessible terms tomorrow; for the time being I just wish to point it out for those who are capable of reading the paper but are too lazy to check the arxiv daily. I know, you belong to this set but you won't admit it!
Okay, just an anticipation: the rate of physics processes yielding a W boson plus four hadronic jets has been computed with improved accuracy, making it more profitable for experimental searches for top quarks as well as signatures of new physics to estimate, identify, and reduce this nasty background. For top-antitop quark searches the W+4 jet process is the leading contamination to the data which one may select to collect "lepton plus jets" top pair candidates. These are the ones, for instance, on which the first Tevatron evidence of the top quark was based, 16 years ago. The seven top pair candidates are shown in a historical CDF plot on the right: from those seven events (shown by the unbroken histogram) the top quark mass was reconstructed to be 174+-12 GeV, a result in amazing agreement to today's precise world average of 173.3+-1.1 GeV ...
(Hatched histograms overlaid to the experimental data represent the expected W+jets background and the sum of W+jets and top processes).
More comments and a more thorough explanation coming tomorrow!
