325 research outputs found
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 ()
distribution of the Higgs boson pair with top-quark mass () effects fully
taken into account. At small values of we resum the
logarithmically-enhanced perturbative QCD contributions up to next-to-leading
logarithmic (NLL) accuracy. At intermediate and large values of we
consistently combine resummation with the fixed-order
results. After integration over , we recover the next-to-leading order
(NLO) result for the inclusive cross section with full dependence on . 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- jet algorithm from gluon-gluon and quark-antiquark scattering and
discuss the inclusion of leading- 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 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
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