Direct Photon Production at Next-to–Next-to-Leading Order

Campbell, John M.; Ellis, R. Keith; Williams, Ciaran

doi:10.1103/physrevlett.118.222001

Cited by 109 publications

(119 citation statements)

References 57 publications

(58 reference statements)

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“…At this level of accuracy it is also necessary to include the effect of NLO electroweak corrections, which are also known for this process [15][16][17][18]. For γ þ jet production, the closelyrelated direct photon process has recently been computed at NNLO in QCD [19] and the NLO EW corrections are known as well [20].…”

Section: Introductionmentioning

confidence: 99%

Driving missing data at the LHC: NNLO predictions for the ratio ofγ+jandZ+j

2017

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Driving missing data at the LHC: NNLO predictions for the ratio of γ + j and Z + j In this paper, we present a calculation of the γ þ j process at next-to-next-to-leading order (NNLO) in QCD and compare the resulting predictions to 8 TeV CMS data. We find good agreement with the shape of the photon p T spectrum, particularly after the inclusion of additional electroweak corrections, but there is a tension between the overall normalization of the theoretical prediction and the measurement. We use our results to compute the ratio of Zð→l þ l − Þ þ j to γ þ j events as a function of the vector boson transverse momentum at NNLO, a quantity that is used to normalize Zð→ννÞ þ j backgrounds in searches for dark matter and supersymmetry. Our NNLO calculation significantly reduces the theoretical uncertainty on this ratio, thus boosting its power for future searches of new physics.

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Section: Introductionmentioning

confidence: 99%

Driving missing data at the LHC: NNLO predictions for the ratio ofγ+jandZ+j

2017

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“…The large scale variations indicate that the NNLO calculations are needed to make more realistic theoretical predictions. Such calculations [40] are now becoming available and will be the subject of further work.…”

Section: The Study Of Scale Uncertaintymentioning

confidence: 99%

“…Although at NLO there are more contributing subprocesses ( ) → ( ) and → and the others from the virtual corrections to the Bornlevel processes, the point-like coupling of the photon to quarks makes the calculations easier [19,20,29] (note that the first calculation of direct photon production at next-tonext-to-leading order (NNLO) accuracy in QCD has also been presented recently [40]). It is established that the annihilation channel is suppressed compared to the other subprocesses at pp colliders such as LHC and RHIC whereas, at the Tevatron that is a pp collider, this channel is relevant [47].…”

Section: Predictions For the Isolated Prompt Photon Production At 13 Tevmentioning

confidence: 99%

“…It should be also noted that we use the kinematic settings introduced in [91]. All calculations in this work are performed using the JetPhox with including all diagrams up to the LO and NLO order of QED and QCD coupling, respectively, defined in the MS renormalization scheme (it is worth pointing out in this context that since the NNLO calculations [40] have not yet been incorporated into any readily available codes like JetPhox, the NLO results are still interesting). The fine-structure constant ( EM ) is set to the JetPhox default of 1/137.…”

Section: Predictions For the Isolated Prompt Photon Production At 13 Tevmentioning

confidence: 99%

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Predictions for the Isolated Prompt Photon Production at the LHC ats= 13 TeV

Goharipour

Mehraban

2017

Advances in High Energy Physics

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The prompt photon production in hadronic collisions has a long history of providing information on the substructure of hadrons and testing the perturbative techniques of QCD. Some valuable information about the parton densities in the nucleon and nuclei, especially of the gluon, can also be achieved by analysing the measurements of the prompt photon production cross section whether inclusively or in association with heavy quarks or jets. In this work, we present predictions for the inclusive isolated prompt photon production in pp collisions at center-of-mass energy of 13 TeV using various modern PDF sets. The calculations are presented as a function of both photon transverse energy and pseudorapidity for the ATLAS kinematic coverage. We also study in detail the theoretical uncertainty in the cross sections due to the variation of the renormalization, factorization, and fragmentation scales. Moreover, we introduce and calculate the ratios of photon momenta for different rapidity regions and study the impact of various input PDFs on such quantity.

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“…For these new data once again the theoretical uncertainties at NLO, this time from JETPHOX [23,24], are larger than the experimental uncertainties. The prompt photon cross section is now also available at NNLO [25].…”

Section: Heavy Flavour Top and Prompt Photon Productionmentioning

confidence: 99%

Constraints on the Parton Density Functions of the Proton by Measurements with the ATLAS Detector

Sutton¹

2018

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2017)

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Parton distribution functions (PDFs) are crucial ingredients for measurements at hadron colliders, since they describe the initial states and therefore critically impact the precision of cross section predictions for observables. This contribution will review recent precision analyses, where the PDFs play an important role and discuss the impact of several new ATLAS cross-section measurements on PDFs of the proton. Particular emphasis will be given to the determination of the strange and the gluon content of the proton.

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Direct Photon Production at Next-to–Next-to-Leading Order

Cited by 109 publications

References 57 publications

Driving missing data at the LHC: NNLO predictions for the ratio ofγ+jandZ+j

Driving missing data at the LHC: NNLO predictions for the ratio ofγ+jandZ+j

Predictions for the Isolated Prompt Photon Production at the LHC ats= 13 TeV

Constraints on the Parton Density Functions of the Proton by Measurements with the ATLAS Detector

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