ar X iv : h ep - p h / 97 11 36 6 v 1 1 8 N ov 1 99 7 406 : Jet Production in DIS at NLO Including Z and W Exchange

Next-to-leading order QCD predictions for 1-jet and 2-jet cross sections in deep inelastic scattering with complete neutral current (γ and Z) and charged current (W) exchange are presented. Electroweak effects in DIS n-jet production are known to become important for Q > ∼ 2500 GeV . These effects can be studied with the fully differential ep → n jets event generator mepjet [1, 2] which allows to analyze any 1or 2-jet like observable in NLO in terms of parton 4-momenta. Numerical results for 1and 2-jet cross sections in ep scattering are shown in Fig. 1. Jets are defined in a cone scheme (in the laboratory frame) with R = 1 and p T (j) > 5 GeV. In addition, we require 0.04 < y < 1, an energy cut of E(e) > 10 GeV on the scattered lepton (in NC scattering) and a cut on the pseudo-rapidity η of the scattered lepton and jets of |η| < 3.5. The Q distribution of the NC 2-jet cross section (including γ and Z exchange) is compared to the CC 2-jet cross section in Fig. 1a. The difference between the ep and ep results in the NC case is entirely due to the additional Z exchange, which increases (decreases) the 1-photon result in the ep (ep) case by more than a factor of two for very high Q. The Q-dependence of the 2-jet rate, defined as the ratio of the 2-jet to the 1-jet cross section, is shown in Fig. 1b for ep scattering in NC (solid) and CC (dashed) exchange. The QCD corrections to the electroweak cross sections are investigated in Figs. 1c-f where the Q dependence of the K-factors for NC and CC 1and 2-jet cross sections are shown. While NC and CC effects differ markedly for ep and ep scattering, the QCD K-factors are largely independent of the initial state lepton. We find very similar K-factors for jets defined in the kT scheme with E T = 40 GeV. More results can be found in [2]. References [1] E. Mirkes and D. Zeppenfeld, Phys. Lett. B380 (1996) 105, [hepph/9511448]; Acta Phys. Pol. B27 (1996) 1393, [hep-ph/9604281]. [2] E. Mirkes, [hep-ph/9711224]. [3] M. Glück, E. Reya and A. Vogt, Zeit. Phys. C67 (1995) 433. [4] A.D. Martin, R.G. Roberts, W.J. Stirling, Phys. Lett. B387 (1996) 419. 1 Talk given by E. Mirkes at the International Europhysics Conference on HighEnergy Physics (HEP 97), Jerusalem, Israel, 19-26 Aug 1997. 2 E. Mirkes, S. Willfahrt and D. Zeppenfeld log10Q 2 [GeV] dσ /d lo g Q 2 [p b] a) e p→ 2 jets NC CC e p e p log10Q [GeV] 2je t r at e b) e p→ 2 jets ___________ e p→ 1 jet NC CC 10 -4 10 -3 10 -2 10 -1 1 10 10 2 10 3 10 4 2 3 4 5 -0.1 0 0.1 0.2 0.3 0.4 0.5