Dynamical parton distributions of the nucleon

Jimenez-Delgado, Pedro

doi:10.1016/j.nuclphysbps.2008.12.012

Cited by 3 publications

(2 citation statements)

References 127 publications

(283 reference statements)

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“…The contributions of twist τ = 3 and higher to the polarized structure functions g 1 (x, Q 2 ) and g 2 (x, Q 2 ) are also investigated. At NNLO the value α s (M 2 Z ) = 0.1132 ± 0.0022 is obtained in good agreement with other determinations [19,20]. An alternative approach to PDFs is based on the statistical model in which the nucleon is regarded as a gas of massless partons in equilibrium at a given temperature in a volume of finite size.…”

Section: Dis 2012supporting

confidence: 82%

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Summary of the Structure Functions Working group at DIS 2012

Cooper-Sarkar,

Jimenez-Delgado,

Plačakytė

2012

Preprint

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Section: Dis 2012supporting

confidence: 82%

“…The ongoing update of the NNLO dynamical parton distributions was presented [20]. This includes several improvements in the framework, e.g.…”

Section: Dis 2012mentioning

confidence: 99%

Summary of the Structure Functions Working group at DIS 2012

Cooper-Sarkar,

Jimenez-Delgado,

Plačakytė

2012

Preprint

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QCD analysis of xF3 structure functions in deep-inelastic scattering: Mellin transform with Gegenbauer polynomials up to N3LO approximation

Arbabifar,

Morshedian,

Ghasemzadeh

et al. 2024

Phys. Rev. C

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New Limits on Intrinsic Charm in the Nucleon from Global Analysis of Parton Distributions

et al. 2015

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We present a new global QCD analysis of parton distribution functions, allowing for possible intrinsic charm (IC) contributions in the nucleon inspired by light-front models. The analysis makes use of the full range of available high-energy scattering data for Q 2 1 GeV 2 and W 2 3.5 GeV 2 , including fixed-target proton and deuteron cross sections at lower energies that were excluded in previous global analyses. The expanded data set places more stringent constraints on the momentum carried by IC, with x IC at most 0.5% (corresponding to an IC normalization of ∼ 1%) at the 4σ level for ∆χ 2 = 1. We also critically assess the impact of older EMC measurements of F c 2 at large x, which favor a nonzero IC, but with very large χ 2 values.There has been considerable interest recently in the nature of Fock states of the proton wave function involving five or more quarks, such as |uudqq , where q = u, d, s or c [1][2][3][4][5][6]. This has arisen partly from attempts to understand flavor asymmetries observed in the nucleon sea, such asd >ū [7,8] and s =s [9], which clearly point to a nonperturbative origin. In addition, there has been a long-standing debate about the existence of intrinsic charm (IC) quarks in the proton, associated with the |uudcc component of the proton wave function.Aside from the intrinsic interest in the role of nonperturbative dynamics in the structure of the nucleon sea, the leptoproduction of charm quarks is also important in providing information on the gluon distribution in the nucleon. A significant IC component in the nucleon wave function could also influence observables measured at the LHC, either directly through enhanced cross sections at large x, or indirectly via the momentum sum rule leading to a decreased momentum fraction carried by gluons.Following early indications from measurements of charm production in pp scattering of an anomalous excess of D mesons at large values of Feynman x F (see [10] and references therein), the proposal was made that the observed enhancement could be accounted for with the addition of intrinsic cc pairs in the nucleon that were not generated through perturbative gluon radiation [11]. Neglecting quark transverse momentum and assuming a charm mass much greater than other mass scales, Brodsky, Hoyer, Peterson and Sakai (BHPS) [11] derived an analytic approximation to the IC distribution that, unlike the perturbatively generated charm, was peaked at relatively large parton momentum fractions x.A number of experimental and theoretical studies have since sought to elucidate this issue, although the evidence has been somewhat inconclusive. Measurements of the charm structure function F [16] employed a hybrid scheme to interpolate between massless evolution at large Q 2 and PGF at low Q 2 , using the BHPS IC model and a model based on fluctuations of the nucleon to charmed baryon and D meson states [17][18][19]. While it was difficult to fit the data simultaneously in terms of a single IC framework, Steffens et al. found a slight preference for IC in the meso...

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Dynamical parton distributions of the nucleon

Cited by 3 publications

References 127 publications

Summary of the Structure Functions Working group at DIS 2012

Summary of the Structure Functions Working group at DIS 2012

QCD analysis of xF3 structure functions in deep-inelastic scattering: Mellin transform with Gegenbauer polynomials up to N3LO approximation

New Limits on Intrinsic Charm in the Nucleon from Global Analysis of Parton Distributions

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