The third-order QCD corrections to deep-inelastic scattering by photon exchange

Vermaseren, J. A. M.; Vogt, A.; Moch, S.

doi:10.1016/j.nuclphysb.2005.06.020

Cited by 422 publications

(499 citation statements)

References 109 publications

(327 reference statements)

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“…The NNLO (2-loop) coefficients c (2) 2,3 have been originally calculated in [50,51] and, for definiteness, we take c (2) 2,NS ≡ c (2)+ 2,NS , c (2) 2,q and c (2) 2,g from [52], and c (2) 3,NS ≡ c (2)− 3,NS from [51]. Since the longitudinal structure function F L = F 2 − 2xF 1 vanishes at LO, it has become common [50] to consider the first nonvanishing O(α s ) contribution to F L as the LO one, i.e., the perturbative…”

Section: Evolutions Of Parton Distributions and Structure Functionsmentioning

confidence: 99%

“…L have been calculated in [52,53], where also the well known LO c (1) L and NLO c (2) L coefficients can be found. Although we perform all calculations in Mellin n-moment space, it should be nevertheless mentioned that in Bjorken-x space the simple products in (14) turn into the standard convolutions of the Wilson coefficients with the parton distributions.…”

Section: Evolutions Of Parton Distributions and Structure Functionsmentioning

confidence: 99%

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Dynamical next-to-next-to-leading order parton distributions

2009

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Utilizing recent DIS measurements (σ r , F 2,3,L ) and data on hadronic dilepton production we determine at NNLO (3-loop) of QCD the dynamical parton distributions of the nucleon generated radiatively from valencelike positive input distributions at an optimally chosen low resolution scale (Q 2 0 < 1 GeV 2 ). These are compared with 'standard' NNLO distributions generated from positive input distributions at some fixed and higher resolution scale (Q 2 0 > 1 GeV 2 ). Although the NNLO corrections imply in both approaches an improved value of χ 2 , typically χ 2 NNLO 0.9χ 2 NLO , present DIS data are still not sufficiently accurate to distinguish between NLO results and the minute NNLO effects of a few percent, despite of the fact that the dynamical NNLO uncertainties are somewhat smaller than the NLO ones and both are, as expected, smaller than those of their 'standard' counterparts. The dynamical predictions for F L (x, Q 2 ) become perturbatively stable already at Q 2 = 2 − 3 GeV 2 where precision measurements could even delineate NNLO effects in the very small-x region. This is in contrast to the common 'standard' approach but NNLO/NLO differences are here less distinguishable due to the larger 1σ uncertainty bands. Within the dynamical approach we obtain α s (M 2 Z ) = 0.1124 ± 0.0020, whereas the somewhat less constrained 'standard' fit gives α s (M 2 Z ) = 0.1158 ± 0.0035.arXiv:0810.4274v2 [hep-ph]

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Section: Evolutions Of Parton Distributions and Structure Functionsmentioning

confidence: 99%

Section: Evolutions Of Parton Distributions and Structure Functionsmentioning

confidence: 99%

Dynamical next-to-next-to-leading order parton distributions

2009

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“…Both coefficient functions and the anomalous dimensions which drive perturbative evolution are now known up to next-to-next-to leading order (and in fact the coefficient function up to NNNLO [21]). Therefore, we will provide determinations of the parton distributions at leading (LO), next-to-leading (NLO) and next-to-next-to leading order (NNLO).…”

Section: Jhep03(2007)039mentioning

confidence: 99%

Neural network determination of parton distributions: the nonsinglet case

Collaboration¹,

Debbio²,

Forte³

et al. 2007

J. High Energy Phys.

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Abstract:We provide a determination of the isotriplet quark distribution from available deep-inelastic data using neural networks. We give a general introduction to the neural network approach to parton distributions, which provides a solution to the problem of constructing a faithful and unbiased probability distribution of parton densities based on available experimental information. We discuss in detail the techniques which are necessary in order to construct a Monte Carlo representation of the data, to construct and evolve neural parton distributions, and to train them in such a way that the correct statistical features of the data are reproduced. We present the results of the application of this method to the determination of the nonsinglet quark distribution up to next-to-next-to-leading order, and compare them with those obtained using other approaches.

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“…See [22,31] for next-to-next-to-leading logarithmic (NNLL) resummation results. Due to several important QCD results at the three loop level that are recently available [32][33][34][35][36][37][38], the resummation upto N 3 LL has also become a reality [39][40][41][42]. The fixed order partial soft-plus-virtual N 3 LO corrections [39,43] to the DY and Higgs productions show the reliability of the perturbation theory and the stability against the scale variations.…”

mentioning

confidence: 99%

QCD threshold corrections to di-lepton and Higgs rapidity distributions beyond N2LO

2007

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We present threshold enhanced QCD corrections to rapidity distributions of di-leptons in the DrellYan process and of Higgs particles in both gluon fusion and bottom quark annihilation processes using Sudakov resummed cross sections. We have used renormalisation group invariance and the mass factorisation theorem that these hard scattering cross sections satisfy as well as Sudakov resummation of QCD amplitudes. We find that these higher order threshold QCD corrections stabilise the theoretical predictions under scale variations.Perturbative Quantum Chromodynamics (pQCD) provides a framework to successfully compute various observables in the collisions of hadrons at high energies. Recent theoretical advances in the computations of higher order QCD radiative corrections have lead to precise results for several important observables. Because of this progress, we can now predict these observables with unprecedented accuracy for physics studies at the Tevatron collider in Fermilab as well as at the upcoming Large Hadron Collider (LHC) in CERN [1].The Drell-Yan (DY) production of di-leptons [2] has been one of the most important probes of the structure of hadrons. It is also one of the dominant production processes at hadron colliders. At the LHC, it will serve as a luminosity monitor which is very important to precisely calibrate the machine for searches for physics beyond the Standard Model (SM). In DY production, a pair of leptons is produced through the decay of virtual photons, Z and W bosons that result from the collisions of incoming partons (quarks and gluons) in the hadrons. At hadron colliders, the DY process provides precise measurements of various standard model parameters. Rapidity distributions of Z bosons [3] and charge asymmetries of leptons coming from W boson decays [4] can probe the structure of the hadrons and possible excess events in di-lepton invariant mass distributions can point to physics beyond the standard model such as R-parity violating supersymmetric models and models with Z ′ , or with contact interactions [5]. Both D0 and CDF collaborations [6] at the Fermilab Tevatron made precise measurements of Z and W production cross sections and asymmetries which not only allowed for stringent tests of the standard model but also play an important role in the Higgs search at future colliders. These measurements are also possible at the LHC due to the large cross sections for the DY process.The other process which is equally important is Higgs boson production at these colliders because it will establish the Standard Model as well as look for beyond the SM Higgs [7,8]. The Higgs boson, which is responsible for the electroweak symmetry breaking in the Standard Model, is yet to be discovered. The search for this particle has been going on at the Fermilab Tevatron and is one of the most important tasks for the CERN LHC. The LEP experiments in the past provided vital information on the possible mass range of this particle [9]. The lower bound on the mass is 114.4 GeV/c 2 and an upper bound is ...

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The third-order QCD corrections to deep-inelastic scattering by photon exchange

Cited by 422 publications

References 109 publications

Dynamical next-to-next-to-leading order parton distributions

Dynamical next-to-next-to-leading order parton distributions

Neural network determination of parton distributions: the nonsinglet case

QCD threshold corrections to di-lepton and Higgs rapidity distributions beyond N2LO

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