Jet and Di-Jet production in Photon-Photon collisions

We present the computation of next-to-leading order (NLO) QCD corrections to di-photon production in association with two or three hard jets in pp collisions at a center-of-mass energy of 8 TeV. The inclusion of NLO corrections is shown to substantially reduce the theoretical uncertainties estimated from scale variations on total cross section predictions. We study a range of differential distributions relevant for phenomenological studies of photon pair production in associa...

Jet and di-jet production are studied in collisions of quasi-real photons collected during the LEP2 program at e+e- center-of-mass energies from 189 to 209 GeV. OPAL reports good agreement of NLO perturbative QCD with the measured differential di-jet cross sections, which reach a mean transverse energy of the di-jet system of 25 GeV. L3, on the other hand, finds drastic disagreement of the same calculation with single jet production for transverse jet momenta larger than abou...

We calculate the NNLO QCD corrections to diphoton production with an additional jet at the LHC. Our calculation represents the first NNLO-accurate prediction for the transverse momentum distribution of the diphoton system. The improvement in the accuracy of the theoretical prediction is significant, by a factor of up to four relative to NLO QCD. Our calculation is exact except for the finite remainder of the two-loop amplitude which is included at leading color. The numerical...

In this talk we present the calculation of next-to-next-to-leading order (NNLO) QCD corrections to dijet production and related observables at hadron colliders in the purely gluonic channel. Results for this channel are obtained keeping all orders of $N_C$ in the colour expansion. We show that the NNLO correction significantly reduces the scale uncertainty compared to next-to-leading order (NLO). We present the NNLO double-differential single jet inclusive cross section where...

Di-jet production is studied in collisions of quasi-real photons radiated by the LEP beams at e+e- centre-of-mass energies 161 and 172 GeV. The jets are reconstructed using a cone jet finding algorithm. The angular distributions of direct and double-resolved processes are measured and compared to the predictions of leading order and next-to-leading order perturbative QCD. The jet energy profiles are also studied. The inclusive two-jet cross-section is measured as a function o...

We study jet production in photon-photon reactions at the next-to-leading logarithm accuracy. The discussion of the theoretical uncertainties and the role of the quark and gluon distributions in the photon is emphasized. The phenomenology at TRISTAN energies is discussed and predictions are made for LEP 200.

Recent progress in application of higher order QCD calculations to jet and inclusive particle production in photon induced collisions is reviewed. Attention is paid to theoretical uncertainties of such calculations, particularly those coming from the choice of renormalization and factorization scales.

We present the next-to-leading order QCD corrections to the production of a photon pair in association with one or two jets. This class of processes constitutes an important background for Higgs physics at the LHC. For the one jet process we include photon fragmentation contributions and perform a comparison between different photon isolation criteria and various isolation parameters. The two jet calculation has been performed using a smooth cone isolation criterion. We find ...

We present the first next-to leading order accurate hadron-level predictions for inclusive QCD and jet observables in photo-production for the upcoming electron--ion collider.

Di-jet producion is studied in collisions of quasi-real photons at e+e- centre- of-mass energies sqrt(s)ee from 189 to 209 GeV at LEP. The data were collected with the OPAL detector. Jets are reconstructed using an inclusive k_t clustering algorithm for all cross-section measurements presented. A cone jet algorithm is used in addition to study the different structure of the jets resulting from either of the algorithms. The inclusive di-jet cross-section is measured as a funct...