Wide-angle scattering in softened field theory

Ezawa, Zyun F.

doi:10.1007/bf02739483

Cited by 111 publications

(85 citation statements)

References 5 publications

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“…As displayed in Fig. VI.41, this result strengthens the disagreement between the data and contact-interaction models, but does not produce as much curvature as expected from either pQCD (Ezawa, 1974;Farrar and Jackson, 1975) or nonperturbative DSE calculations (Hecht et al, 2001). This discrepancy persists to this day and is one of the outstanding problems in understanding the application of QCD to real-world data.…”

Section: Grv/gjr Distribution Functionssupporting

confidence: 60%

“…The QCD parton model (Ezawa, 1974;Farrar and Jackson, 1975), which determines the pion distribution function from the process depicted in Fig. III.17, indicates that at very high x the distribution should behave as (1−x) 2 .…”

Section: E the Pion Structure Functionmentioning

confidence: 99%

“…Perturbative quantum chromodynamics (pQCD) (Brodsky et al, 1995;Ji et al, 2005) and continuum non-perturbative calculations, such as Dyson-Schwinger Equation (DSE) studies dependence of the pion structure function at very high x (Ezawa, 1974;Farrar and Jackson, 1975). (Bloch et al, 2000(Bloch et al, , 1999Hecht et al, 1999Hecht et al, , 2001Maris and Roberts, 2003), which express the momentum-dependence of the dressed-quark mass function that is evident in Fig.…”

Section: E the Pion Structure Functionmentioning

confidence: 99%

“…(VI.29) in context, the parton model prediction for the pion's valence-quark distribution function is (Berger and Brodsky, 1979;Brodsky and Lepage, 1979;Ezawa, 1974;Farrar and Jackson, 1975): 11…”

Section: Pion Structure Function In the Topological Soliton Modelmentioning

confidence: 99%

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Nucleon and pion distribution functions in the valence region

2010

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We provide an experimental and theoretical perspective on the behavior of unpolarized distribution functions for the nucleon and pion on the valence-quark domain; namely, Bjorken-x > ∼ 0.4. This domain is key to much of hadron physics; e.g., a hadron is defined by its flavor content and that is a valence-quark property. Furthermore, its accurate parametrization is crucial to the provision of reliable input for large collider experiments. We focus on experimental extractions of distribution functions via electron and muon inelastic scattering, and from Drell-Yan interactions; and on theoretical treatments that emphasize an explanation of the distribution functions, providing an overview of major contemporary approaches and issues. Valence-quark physics is a compelling subject, which probes at the heart of our understanding of the Standard Model. There are numerous outstanding and unresolved challenges, which experiment and theory must confront. In connection with experiment, we explain that an upgraded Jefferson Lab facility is well-suited to provide new data on the nucleon, while a future electron ion collider could provide essential new data for the mesons. There is also great potential in using Drell-Yan interactions, at FNAL, J-PARC and GSI, to push into the large-x domain for both mesons and nucleons. We argue furthermore that explanation, in contrast to modeling and parametrization, requires a widespread acceptance of the need to adapt theory: to the lessons learnt already from the methods of nonperturbative quantum field theory; and a fuller exploitation of those methods. * Electronic address: holt@anl.gov † Electronic address: cdroberts@anl.gov

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Section: Grv/gjr Distribution Functionssupporting

confidence: 60%

Section: E the Pion Structure Functionmentioning

confidence: 99%

Section: E the Pion Structure Functionmentioning

confidence: 99%

Section: Pion Structure Function In the Topological Soliton Modelmentioning

confidence: 99%

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Nucleon and pion distribution functions in the valence region

2010

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“…Moreover, given the large value of the ratio of s-to-u current-quark masses, a comparison between the pion and kaon structure functions offers the chance to chart effects of explicit chiral symmetry breaking on the structure of would-be Goldstone modes. There is also the prediction [24,25] that a theory in which the quarks interact via 1/k 2 vector-boson exchange will produce valence-quark distribution functions for v /u π v should equal the ratio of kaon-to-pion Drell-Yan cross-sections, and we reproduce that obtained from a sample of dimuon events with invariant mass 4.1 < M < 8.5 GeV [26].…”

supporting

confidence: 68%

Empirically charting dynamical chiral symmetry breaking

Chang¹,

Roberts²,

Melnitchouk³

2010

AIP Conference Proceedings

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The goal of hadron physics is the provision of a quantitative explanation of the properties of hadrons through a solution of quantum chromodynamics (QCD). This is a fundamental problem that is unique in the history of science: never before have we been confronted by a theory whose elementary excitations are not those degrees-of-freedom readily accessible via experiment. Moreover, QCD generates forces which are so strong that less-than 2% of a nucleon's mass can be attributed to the so-called current-quark masses that appear in the QCD Lagrangian; viz., forces that generate mass from almost nothing, a phenomenon known as dynamical chiral symmetry breaking (DCSB).Neither confinement nor DCSB is apparent in QCD's Lagrangian and yet they play the dominant role in determining the observable characteristics of real-world QCD. The physics of hadrons is ruled by emergent phenomena, such as these, which can only be elucidated through the employment of nonperturbative methods in quantum field theory. This is both the greatest novelty and the greatest challenge within the Standard Model. We must find essentially new ways and means to explain precisely via mathematics the observable content of QCD. Herein we provide a snapshot of recent progress in hadron physics made using QCD's Dyson-Schwinger equations (DSEs). The complex of DSEs is a powerful tool, which has been employed with marked success to study confinement and DCSB, and their impact on hadron observables. This is apparent from Ref. [1].Asymptotic coloured states have not been observed, so no solution to QCD will be complete if it does not explain confinement. This means confinement in the real world, which contains quarks with light current-quark masses. That is distinct from the artificial universe of pure-gauge QCD without dynamical quarks, studies of which tend merely to focus on achieving an area law for a Wilson loop and hence are irrelevant to the question of light-quark confinement.Confinement can be related to the analytic properties of QCD's Schwinger functions [2] and can therefore be translated into the challenge of charting the infrared behavior of QCD's universal β -function. This is a well-posed problem whose solution can be addressed in any framework enabling the nonperturbative evaluation of renormalisation constants. In this connection we note that the hadron spectrum [3], and hadron elastic and transition form factors [4,5] provide unique information about the long-range interaction between light-quarks and, in addition, the distribution of a hadron's characterising

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