Dijet production at HERA in next-to-leading order

Abstract

Two-jet cross sections in deep inelastic scattering at HERA are calculated in next-to-leading order. The QCD corrections are implemented in a new ep → n jets event generator, MEPJET, which allows to analyze arbitrary jet definition schemes and general cuts in terms of parton 4-momenta. First results are presented for the JADE, the cone and the k T schemes. For the W -scheme, disagreement with previous results and large radiative corrections and recombination scheme dependencies are traced to a common origin.

Event shapes in e+e annihilation and deep inelastic scattering

“…Beyond leading order, perturbative calculations involve complex cancellations between soft and collinear real and virtual contributions and are nearly always left to general-purpose "fixed-order Monte Carlo" programs. The current state of the art is next-to-leading order (NLO), and available programs include: for e + e − to 3 jets, EVENT [41], EERAD [42] and EVENT2 [43]; for e + e − to 4 jets, Menlo Parc [44], Mercutio [45] and EERAD2 [46]; for DIS to 2+1 jets, MEPJET [47], DISENT [43] and DISASTER++ [48]; and for all the above processes and additionally DIS to 3 + 1 jets and various hadron-hadron and photo-production processes, NLOJET++ [49,50] (for photo-production, there is additionally JETVIP [51]). In recent years much progress has been made towards NNLO calculations, though complete results remain to be obtained (for a review of the current situation, see [52]).…”

Antenna subtraction with hadronic initial states

“…Several NLO calculations are already available in the literature both for the DIS jet production [3,23] and for the vector boson production [24].…”

Investigation of power corrections to event shape variables measured in deep-inelastic scattering

“…In order to test the reliability of the perturbative predictions, careful comparisons of MEPJET [19], DISENT and DISASTER++ [20] have been carried out [21]. Due to intrinsic restrictions of the integration technique applied in MEPJET (phase space slicing), however, it can not be used for the mean event shapes.…”

“…(iii) In the power corrections eqs. (18), (19) and (20) it is not obvious which number of flavours to take. As default N f = 5 is used for the perturbative part and the subtraction terms and N f = 3 in the coefficients of the power corrections.…”