NNLO QCD corrections to diphoton production with an additional jet at the LHC

Chawdhry, Herschel A.; Czakon, Michał; Mitov, Alexander; Poncelet, Rene

doi:10.1007/jhep09(2021)093

Cited by 67 publications

(55 citation statements)

References 42 publications

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“…By using a dynamical photon isolation, which regulates any parton-photon collinear configurations and discards the fragmentation contribution, these singularities can be handled with generic QCD subtraction methods up to NNLO. Following this procedure, NNLO results have been obtained for photon-plus-jet production [26,27], di-photon production [29][30][31][32], di-photon-plus-jet production [33,34] and tri-photon production [35,36]. In the following, it is assumed that the genuine QCD singularities have already been handled using antenna subtraction, such that only the remaining parton-photon collinear singularities remain to be dealt with.…”

Section: Photon Production Cross Sectionmentioning

confidence: 99%

Photon Fragmentation in the Antenna Subtraction Formalism

Gehrmann,

Schürmann

2022

Preprint

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The theoretical description of photon production at particle colliders combines direct photon radiation and fragmentation processes, which can not be separated from each other for definitions of photon isolation used in experimental measurements. The theoretical description of these processes must account for collinear parton-photon configurations, retaining the dependence on the photon momentum fraction, and includes the parton-to-photon fragmentation functions. We extend the antenna subtraction method to include photon fragmentation processes up to next-to-next-to-leading order (NNLO) in QCD. Collinear photon radiation is handled using newly introduced fragmentation antenna functions and associated phase space mappings. We derive the integrated forms of the fragmentation antenna functions and describe their interplay with the mass factorisation of the photon fragmentation functions. The construction principles of antenna subtraction terms up to NNLO for identified photons are outlined, thereby enabling the application of the method to different photon production processes at colliders.

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Section: Photon Production Cross Sectionmentioning

confidence: 99%

Photon Fragmentation in the Antenna Subtraction Formalism

Gehrmann,

Schürmann

2022

Preprint

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“…It is worth noting, that the Nnlojet prediction for p T,γγ > 0 is only NLO accurate, and an even higher-order calculation would be needed to describe these phase-space regions at NNLO accuracy, e.g. γγ+jet at NNLO [66].…”

Section: Differential Cross Sectionsmentioning

confidence: 99%

Measurement of the production cross section of pairs of isolated photons in pp collisions at 13 TeV with the ATLAS detector

Collaboration

Aad

Abbott

et al. 2021

J. High Energ. Phys.

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A measurement of prompt photon-pair production in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV is presented. The data were recorded by the ATLAS detector at the LHC with an integrated luminosity of 139 fb−1. Events with two photons in the well-instrumented region of the detector are selected. The photons are required to be isolated and have a transverse momentum of $$ {p}_{\mathrm{T}{,}_{\gamma 1(2)}} $$ p T , γ 1 2 > 40 (30) GeV for the leading (sub-leading) photon. The differential cross sections as functions of several observables for the diphoton system are measured and compared with theoretical predictions from state-of-the-art Monte Carlo and fixed-order calculations. The QCD predictions from next-to-next-to-leading-order calculations and multi-leg merged calculations are able to describe the measured integrated and differential cross sections within uncertainties, whereas lower-order calculations show significant deviations, demonstrating that higher-order perturbative QCD corrections are crucial for this process. The resummed predictions with parton showers additionally provide an excellent description of the low transverse-momentum regime of the diphoton system.

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“…At next-to-next-to-leading order (NNLO) the required two-loop amplitudes still need to be derived on a process-by-process basis. To date, full NNLO predictions for 2 → 2 processes are widely available (see [11][12][13][14][15][16][17][18][19] for recent progress), while for 2 → 3 processes only a few two-loop amplitudes [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] and pioneering NNLO results [36][37][38][39] exist. The complexity and the status of NLO calculations for loop-induced processes is similar, with an increasing number of 2 → 2 predictions [40][41][42][43][44] and first results for 2 → 3 processes [45].…”

Section: Introductionmentioning

confidence: 99%

Two-loop tensor integral coefficients in OpenLoops

Pozzorini,

Schär,

Zoller

2022

Preprint

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We present a new and fully general algorithm for the automated construction of the integrands of two-loop scattering amplitudes. This is achieved through a generalisation of the open-loops method to two loops. The core of the algorithm consists of a numerical recursion, where the various building blocks of two-loop diagrams are connected to each other through process-independent operations that depend only on the Feynman rules of the model at hand. This recursion is implemented in terms of tensor coefficients that encode the polynomial dependence of loop numerators on the two independent loop momenta. The resulting coefficients are ready to be combined with corresponding tensor integrals to form scattering probability densities at two loops. To optimise CPU efficiency we have compared several algorithmic options identifying one that outperforms naive solutions by two orders of magnitude. This new algorithm is implemented in the OpenLoops framework in a fully automated way for two-loop QED and QCD corrections to any Standard Model process. The technical performance is discussed in detail for several 2 → 2 and 2 → 3 processes with up to order 10 5 two-loop diagrams. We find that the CPU cost scales linearly with the number of two-loop diagrams and is comparable to the cost of corresponding real-virtual ingredients in a NNLO calculation. This new algorithm constitutes a key building block for the construction of an automated generator of scattering amplitudes at two loops.

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NNLO QCD corrections to diphoton production with an additional jet at the LHC

Cited by 67 publications

References 42 publications

Photon Fragmentation in the Antenna Subtraction Formalism

Photon Fragmentation in the Antenna Subtraction Formalism

Measurement of the production cross section of pairs of isolated photons in pp collisions at 13 TeV with the ATLAS detector

Two-loop tensor integral coefficients in OpenLoops

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