Reconsideration of the inclusive prompt photon production at the LHC with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>k</mml:mi><mml:mi>T</mml:mi></mml:msub></mml:math>-factorization

Lipatov, A. V.; Malyshev, M. A.

doi:10.1103/physrevd.94.034020

Cited by 29 publications

(31 citation statements)

References 38 publications

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“…The isolation requirement significantly (up to ∼ 10% of the visible cross section) reduces contribution from the so-called photon fragmentation mechanisms, not implemented into the pegasus. The isolation criterion and additional conditions which preserve our calculations from divergences have been specially discussed, for example, in [52] Open heavy flavor production…”

Section: Simulated Processesmentioning

confidence: 99%

Particle event generator: a simple-in-use system PEGASUS version 1.0

2020

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pegasus is a parton-level Monte-Carlo event generator designed to calculate cross sections for a wide range of hard QCD processes at high energy pp and pp collisions, which incorporates the dynamics of transverse momentum dependent (TMD) parton distributions in a proton. Being supplemented with off-shell production amplitudes for a number of partonic subprocesses and provided with necessary TMD gluon density functions, it produces weighted or unweighted event records which can be saved as a plain data file or a file in a commonly used Les Houches Event format. A distinctive feature of the pegasus is an intuitive and extremely user friendly interface, allowing one to easily implement various kinematical cuts into the calculations. Results can be also presented "on the fly" with built-in tool pegasus plotter. A short theoretical basis is presented and detailed program description is given.

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Section: Simulated Processesmentioning

confidence: 99%

Particle event generator: a simple-in-use system PEGASUS version 1.0

2020

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“…Measurements of inclusive prompt-photon production also provide benchmarks to use in investigating novel approaches to parton radiation [12], next-to-leading-order (NLO) QCD corrections with matched parton showers [13], the relevance of threshold logarithms in QCD and electroweak corrections [14] and NNLO QCD corrections [15][16][17]. More specifically, the production of prompt photons, which is less sensitive to hadronisation effects than that of jets, can be used to pursue an alternative QCD description based on the k T factorisation approach combining off-shell amplitudes and transverse-momentum-dependent parton densities [12]. The prompt-photon data allow the investigation of the fragmentation contribution, which can be done either via fragmentation functions or through the inclusion of parton showers [13].…”

Section: Introductionmentioning

confidence: 99%

Measurement of the inclusive isolated-photon cross section in pp collisions at $$ \sqrt{s} $$ = 13 TeV using 36 fb−1 of ATLAS data

Aad

Abbott²,

Abbott³

et al. 2019

J. High Energ. Phys.

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Measurement of the inclusive isolated-photon cross section in pp collisions at √ s = 13 TeV using 36 fb −1 of ATLAS dataThe ATLAS CollaborationThe differential cross section for isolated-photon production in pp collisions is measured at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC using an integrated luminosity of 36.1 fb −1 . The differential cross section is presented as a function of the photon transverse energy in different regions of photon pseudorapidity. The differential cross section as a function of the absolute value of the photon pseudorapidity is also presented in different regions of photon transverse energy. Next-to-leading-order QCD calculations from Jetphox and Sherpa as well as next-to-next-to-leading-order QCD calculations from Nnlojet are compared with the measurement, using several parameterisations of the proton parton distribution functions. The predictions provide a good description of the data within the experimental and theoretical uncertainties. c 2019 CERN for the benefit of the ATLAS Collaboration. Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license. γ T > 125 GeV and |η γ | < 2.37, excluding the region 1.37 < |η γ | < 1.56. In addition, the double-differential cross section as a function of |η γ | in different regions of E γ T is also presented. The results are based on a data sample with a more than ten-fold increase in statistics relative to the previous study [5]. The measurement presented here is found to be consistent with the previous one in the overlapping kinematic regions. This increase in statistics allows improvements in the calibration of the photon energy and reductions in the experimental systematic uncertainties affecting the cross-section measurement, as well as an extension of the coverage in E γ T to higher values than previously measured. In this analysis, the region where the measurement is limited by systematic uncertainties is extended to E γ T ∼ 1 TeV, beyond what was achieved in the previous measurement. The NLO QCD predictions of Jetphox [19,20] and Sherpa [21] based on several parameterisations of the PDFs are compared with the measurement. The NNLO QCD prediction of Nnlojet [16], which has significantly reduced uncertainties due to fewer missing higher-order terms, is also confronted with the data. ATLAS detectorThe ATLAS detector [22][23][24] is a multipurpose detector with a forward-backward symmetric cylindrical geometry. It consists of an inner tracking detector surrounded by a thin superconducting solenoid, electromagnetic and hadronic calorimeters, and a muon spectrometer incorporating three large superconducting toroid magnets. The inner-detector system is immersed in a 2 T axial magnetic field and provides charged-particle tracking in the range |η| < 2.5. The high-granularity silicon pixel detector is closest to the interaction region and provides four measurements per track. The pixel detector is followed by the silicon microstrip tracker, which typically provides four three-dimension...

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“…The latter two corrections are computed simultaneously on an event-by-event basis [18] and the combined correction is typically 2 GeV. The combined correction 3 Conversion vertex candidates are reconstructed from pairs of oppositely charged tracks in the inner detector that are likely to be electrons [28]. 4 The relative energy resolution is parameterised as σ(E)/E = a/ √ E ⊕ c, where a is the sampling term and c is the constant term.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the cross section for inclusive isolated-photon production in pp collisions at s=13 TeV using the ATLAS detector

Aaboud¹,

Berger²,

Burger³

et al. 2017

Physics Letters B

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Measurement of the cross section for inclusive isolated-photon production in pp collisions at √ s = 13 TeV using the ATLAS detectorThe ATLAS Collaboration Inclusive isolated-photon production in pp collisions at a centre-of-mass energy of 13 TeV is studied with the ATLAS detector at the LHC using a data set with an integrated luminosity of 3.2 fb −1 . The cross section is measured as a function of the photon transverse energy above 125 GeV in different regions of photon pseudorapidity. Next-to-leading-order perturbative QCD and Monte Carlo event-generator predictions are compared to the cross-section measurements and provide an adequate description of the data.The production of prompt photons in proton-proton (pp) collisions, pp → γ + X, provides a testing ground for perturbative QCD (pQCD) with a hard colourless probe. All photons produced in pp collisions that are not secondaries from hadron decays are considered as "prompt". Two processes contribute to prompt-photon production in pp → γ + X: the direct process, in which the photon originates directly from the hard interaction, and the fragmentation process, in which the photon is emitted in the fragmentation of a high transverse momentum (p T ) parton [1,2]. Measurements of inclusive prompt-photon production were used recently to investigate novel approaches to the description of parton radiation [3] and the importance of resummation of threshold logarithms in QCD and of the electroweak corrections [4].Comparisons of prompt-photon data and pQCD are usually limited by the theoretical uncertainties associated with the missing higher-order terms in the perturbative expansion. The extension of the recent next-to-next-to-leading-order (NNLO) pQCD calculations for jet production [5] to prompt-photon production 1 will allow a more stringent test of pQCD. To make such a test with small experimental and theoretical uncertainties, it is optimal to perform measurements of prompt-photon production at high photon transverse energies and at the highest possible centre-of-mass energy of the colliding particles.Since the dominant production mechanism in pp collisions at the LHC proceeds via the qg → qγ process, measurements of prompt-photon production are sensitive at leading order (LO) to the gluon density in the proton [7][8][9][10][11][12][13][14][15][16]. Although prompt photon data were initially included in the determination of the proton parton distribution functions (PDFs), their use was abandoned some years ago. Since then, theoretical developments [13, 14] have shown ways to improve the description of the data in terms of pQCD, and a recent study quantified the impact of prompt-photon data from hadron colliders on the gluon density in the proton [15]. New measurements of prompt-photon production at higher centre-of-mass energies are expected to further constrain the gluon density in the proton when combined with previous data.These measurements can also be used to tune the Monte Carlo (MC) models to improve the understanding of prompt-photon production. In addition...

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Reconsideration of the inclusive prompt photon production at the LHC withkT-factorization

Cited by 29 publications

References 38 publications

Particle event generator: a simple-in-use system PEGASUS version 1.0

Particle event generator: a simple-in-use system PEGASUS version 1.0

Measurement of the inclusive isolated-photon cross section in pp collisions at $$ \sqrt{s} $$ = 13 TeV using 36 fb−1 of ATLAS data

Measurement of the cross section for inclusive isolated-photon production in pp collisions at s=13 TeV using the ATLAS detector

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