Perturbative QCD description of jet data from LHC Run-I and Tevatron Run-II

We present a systematic comparison of jet predictions at the LHC and the Tevatron, with accuracy up to next-to-next-to-leading order (NNLO). The exact computation at NNLO is completed for the gluons-only channel, so we compare the exact predictions for this channel with an approximate prediction based on threshold resummation, in order to determine the regions where this approximation is reliable at NNLO. The kinematic regions used in this study are identical to the experimental setup used by recently published jet data from the ATLAS and CMS experiments at the LHC, and CDF and D0 experiments at the Tevatron. We study the effect of choosing different renormalisation and factorisation scales for the NNLO exact prediction and as an exercise assess their impact on a PDF fit including these corrections. Finally we provide numerical values of the NNLO k-factors relevant for the LHC and Tevatron experiments.Comment: 51 pages, 13 figures, 35 tables. Final version, matches published version in JHE

Transverse-momentum resummation for Higgs boson pair production at the LHC with top-quark mass effects

We consider Higgs boson pair production via gluon fusion in hadronic collisions. We report the calculation of the transverse-momentum ($q_T$) distribution of the Higgs boson pair with top-quark mass ($M_t$) effects fully taken into account. At small values of $q_T$ we resum the logarithmically-enhanced perturbative QCD contributions up to next-to-leading logarithmic (NLL) accuracy. At intermediate and large values of $q_T$ we consistently combine resummation with the ${\cal O}(\alpha_S^3)$ fixed-order results. After integration over $q_T$, we recover the next-to-leading order (NLO) result for the inclusive cross section with full dependence on $M_t$. We present illustrative numerical results at LHC energies, together with an estimate of the corresponding perturbative uncertainties, and we study the impact of the top-quark mass effects.Comment: 11 pages, 2 figures, matches version published in JHE

Precise QCD predictions for jet production at the LHC

Theoretical predictions used in experimental analysis of LHC data have an inherent theoretical uncertainty associated to the relevant order in the perturbative expansion that the observable is computed. In this talk we briefly introduce and motivate the topic of QCD radiative corrections stressing the impact of including higher-order QCD effects in the theory predictions and in particular we consider two-loop QCD corrections. We present numerical results at NNLO for gluonic jet production where jets are reconstructed using the anti-$k_T$ jet algorithm from gluon-gluon and quark-antiquark scattering and discuss the inclusion of leading-$N_F$ quark contributions in the final-state.Comment: 8 pages, 8 figures, Presented at the International Symposium on Multiparticle Dynamics (ISMD 2014), Bologna, Italy, September 8-12, 2014. EPJ Web of Conferences, to appea

NNLO predictions for Z-boson pair production at the LHC

We present a calculation of the NNLO QCD corrections to Z-boson pair production at hadron colliders, based on the N-jettiness method for the real radiation parts. We discuss the size and shape of the perturbative corrections along with their associated scale uncertainties and compare our results to recent LHC data at $\sqrt{s}=13$ TeV.Comment: 19 pages, 2 Tables, 4 figures. Version to appear in JHE

Infrared subtraction at next-to-next-to-leading order for gluonic initial states

In this thesis we describe a procedure for isolating the infrared singularities present in gluonic scattering amplitudes at next-to-leading and next-to-next-to-leading order. We adopted the antenna subtraction framework which has been successfully applied to the calculation of NNLO corrections to the 3-jet cross section and related event shape distributions in electron-positron annihilation. We consider processes with coloured particles in the initial state, and in particular two-jet production in hadron-hadron collisions at accelerators such as the Large Hadron Collider (LHC). We derive explicit formulae for subtracting the single and double unresolved contributions from the double radiation gluonic processes using antenna functions with initial state partons. We show numerically that the subtraction term effectively approximates the matrix element in the various single and double unresolved configurations

Second order QCD corrections to gluonic jet production at hadron colliders

We report on the calculation of the next-to-next-to-leading order (NNLO) QCD corrections to the production of two gluonic jets at hadron colliders. In previous work, we discussed gluonic dijet production in the gluon-gluon channel. Here, for the first time, we update our numerical results to include the leading colour contribution to the production of two gluonic jets via quark-antiquark scattering.Comment: 8 pages, 4 figures, Proceedings of "Loops and Legs in Quantum Field Theory", Weimar April 201