Why Precision ?
Johannes Blümlein A · 2013
PoS(RADCOR2011)048 Why Precision?Johannes Blümlein PoS(RADCOR2011)048Why Precision?Johannes Blümlein instabilities due to large cancellations, which needs special implementations [60].At this conference reports were given on a variety of multi-leg processes.Hard multi-particle processes at NLO QCD were discussed in [61,62].The NLO QCD corrections to hadronic W + W -b b production have been calculated in [44,63].This process is of importance to measure the t t cross section and its background for this channel of final states.As an example we show in Fig. 2 the invariant M e + b mass for the process pp → W + W -b b + X. Results on multi-boson (+ jet) production were discussed in [64,65].The tensor reduction algorithm for one-loop multileg Feynman integrals is of importance to obtain stable numerical results.It has been derived and implemented up to seven-point functions in [66].New results by the GRACE-collaboration have been presented in [67].The Golem and Samurai projects have recently been united allowing for further advanced calculations [68].The calculation of the process W + W -j j at NLO was discussed in [69].A recursive one-loop algorithm for many-particle amplitudes has been presented in [70].The signal-background interference in gg → H → VV , being not small, has been discussed in [71], see also [72].Electro-weak and QCD corrections to pp → Z * + exponentiation have been implemented in the code Herwiri2.0[73].New aspects in the automation of Standard Model processes in MadLoop were described in [74].Alternative NLO subtraction schemes were discussed in [75].Using the Berends-Giele [52, 53] and unitarity method, 1-loop corrections to multi jets up to 12-14 gluons were calculated in [76].At hadron colliders double parton scattering occurs, i.e. two partonic emissions from a single initial state nucleon contribute in a scattering process.For this process electro-weak boson production has been calculated in [77].Very efficient multi-leg tools at NLO have been created during the last years, which allow the calculation of virtual corrections and real emission.Some of them are equipped with hadronic shower algorithms.A number of packages allow to import newly calculated cross sections for individual reactions in a standardized way.We list a series of codes in alphabetic order.