James Currie

NNLO QCD corrections to jet production at hadron colliders from gluon scattering

A bstractWe present the next-to-next-to-leading order (NNLO) QCD corrections to dijet production in the purely gluonic channel retaining the full dependence on the number of colours. The sub-leading colour contribution in this channel first appears at NNLO and increases the NNLO correction by around 10% and exhibits a pT dependence, rising from 8% at low pT to 15% at high pT. The present calculation demonstrates the utility of the antenna subtraction method for computing the full colour NNLO corrections to dijet production at the Large Hadron Collider.

Infrared structure at NNLO using antenna subtraction

A bstractWe consider the infrared structure of hadron-hadron collisions at next-to-next-to leading order using the antenna subtraction method. The general form of the subtraction terms is presented for double real, real-virtual and double virtual contributions. At NLO and NNLO it is shown that the virtual and double virtual subtraction terms can be written in terms of integrated dipoles, formed by systematically combining the mass factorisation contributions and integrated antenna functions. The integrated dipoles describing ℓ unresolved partons, denoted

Single Jet Inclusive Production for the Individual Jet

J_2^{{\left( \ell \right)}}

p_{\rm T}

, are related to Catani’s IR singularity operators,

Scale Choice at the LHC

I_{ij}^{{\left( \ell \right)}}\left( \in \right)

Second order QCD corrections to gluonic jet production at hadron colliders

. It is shown that the IR pole structure of the virtual and double virtual contributions can be written as a sum over integrated dipoles within the antenna subtraction formalism and the master expressions analogous to Catani’s one- and two-loop factorisation formulae are derived. To demonstrate the techniques described in this paper, we apply antenna subtraction to the production of two gluon jets via quark-antiquark scattering at NLO and NNLO. Double real, real-virtual and double virtual subtraction terms are explicitly derived for the leading colour NNLO contribution.

Antenna Subtraction in pQCD at NNLO

We study the single jet inclusive cross section up to next-to-next-to leading order in perturbative QCD, implemented in the parton-level event generator NNLOJET. Our results are fully differential in the jet transverse momentum and rapidity, and we apply fiducial cuts for comparison with the available ATLAS 7 TeV 4.5 fb−1 data for jet radius R = 0.4. For the theoretical calculation, we employ the antenna subtraction method to reliably cancel all infrared divergences present at intermediate stages of the calculation. We present all results using the individual jet transverse momentum µR = µF ∼ pT as the renormalization and factorization scale for each jet’s contribution to the single jet inclusive cross section. Finally, we consider the differences between our predictions using this scale choice to those for the leading jet transverse momentum scale choice, with reference to the ATLAS data.

arXiv : Jet cross sections and transverse momentum distributions with NNLOJET

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.

NNLO QCD corrections to dijet production at hadron colliders

In this talk I discuss the antenna subtraction method for isolating infrared (IR) singularities of jet cross sections in perturbative QCD. The method is applied at next-to-next-to-leading order (NNLO) to dijet production in hadron collisions at the LHC. The double real radiative corrections to the dijet cross section are considered and their IR behaviour is examined. IR subtraction terms are constructed to absorb numerical divergences of the cross section in the single and double unresolved regions of phase space using the antenna subtraction method. A pictorial representation of matrix elements and antenna functions is presented with specific examples of how such diagrams can be used in practical calculations.

Jet cross sections with NNLOJET

This talk discusses recent results for next-to-next-to-leading order (NNLO) QCD corrections to jet cross sections and transverse momentum distributions. The results are obtained in the NNLOJET code framework, which provides an implementation of the antenna subtraction method for the handling of infrared singular contributions at NNLO. We briefly describe the NNLOJET implementation, with particular emphasis on the construction of the real radiation phase space, which is tailored to ensure stability in all infrared sensitive regions.