From the nucleus to the quarks

Holt, R. J.; Arrington, J.; Melnitchouk, Wally

doi:10.1063/1.3479366

Cited by 3 publications

(3 citation statements)

References 14 publications

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“…Plainly, contemporary experiment-based analyses do not provide a particularly discriminating constraint. Future experiments with a tritium target could help [60]. …”

Section: B Sachs Form Factorsmentioning

confidence: 99%

Nucleon and Roper electromagnetic elastic and transition form factors

et al. 2012

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We compute nucleon and Roper electromagnetic elastic and transition form factors using a Poincaré-covariant, symmetry-preserving treatment of a vector × vector contact-interaction. Obtained thereby, the electromagnetic interactions of baryons are typically described by hard form factors. In contrasting this behaviour with that produced by a momentum-dependent interaction, one achieves comparisons which highlight that elastic scattering and resonance electroproduction experiments probe the evolution of the strong interaction's running masses and coupling to infrared momenta. For example, the existence, and location if so, of a zero in the ratio of nucleon Sachs form factors are strongly influenced by the running of the dressed-quark mass. In our description of the nucleon and its first excited state, diquark correlations are important. These composite and fully-interacting correlations are instrumental in producing a zero in the Dirac form factor of the proton's d-quark; and in determining the ratio of d-to-u valence-quark distributions at x = 1, as we show via a simple formula that expresses dv/uv(x = 1) in terms of the nucleon's diquark content. The contact interaction produces a first excitation of the nucleon that is constituted predominantly from axial-vector diquark correlations. This impacts greatly on the γ * p → P11(1440) form factors, our results for which are qualitatively in agreement with the trend of available data. Notably, our dressed-quark core contribution to F2 * (Q 2 ) exhibits a zero at Q 2 ≈ 0.5 m 2 N . Faddeev equation treatments of a hadron's dressed-quark core usually underestimate its magnetic properties, hence we consider the effect produced by a dressed-quark anomalous electromagnetic moment. Its inclusion much improves agreement with experiment. On the domain 0 < Q 2 2 GeV 2 , meson-cloud effects are conjectured to be important in making a realistic comparison between experiment and hadron structure calculations. We find that our computed helicity amplitudes are similar to the bare amplitudes inferred via coupled-channels analyses of the electroproduction process. This supports a view that extant hadron structure calculations, which typically omit meson-cloud effects, should directly be compared with the bare-masses, -couplings, etc., determined via coupled-channels analyses.

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“…Plainly, contemporary experiment-based analyses do not provide a particularly discriminating constraint. Future experiments with a tritium target could help [60]. …”

Section: B Sachs Form Factorsmentioning

confidence: 99%

Nucleon and Roper electromagnetic elastic and transition form factors

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Plainly, contemporary experiment-based analyses do not provide a particularly discriminating constraint. Future experiments with a tritium target should help [267], emphasising again the critical interplay between experiment and theory in elucidating the nature of the strong interaction.…”

Section: Nucleon Form Factorsmentioning

confidence: 99%

Collective Perspective on Advances in Dyson—Schwinger Equation QCD

Bashir¹,

Chang²,

Cloët³

et al. 2012

Commun. Theor. Phys.

333

405

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We survey contemporary studies of hadrons and strongly interacting quarks using QCD's DysonSchwinger equations, addressing: aspects of confinement and dynamical chiral symmetry breaking; the hadron spectrum; hadron elastic and transition form factors, from small-to large-Q 2 ; parton distribution functions; the physics of hadrons containing one or more heavy quarks; and properties of the quark gluon plasma.

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“…Plainly, contemporary experiment-based analyses do not provide a particularly discriminating constraint. Future experiments with a tritium target should help [272], emphasising again the critical interplay between experiment and theory in elucidating the nature of the strong interaction.…”

Section: Valence-quark Distributions At X =mentioning

confidence: 99%

Strong QCD and Dyson–Schwinger equations

Roberts

2015

Faà Di Bruno Hopf Algebras, Dyson–Schwinger Equations, and Lie–Butcher Series

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The real-world properties of quantum chromodynamics (QCD) -the stronglyinteracting piece of the Standard Model -are dominated by two emergent phenomena: confinement; namely, the theory's elementary degrees-of-freedom -quarks and gluonshave never been detected in isolation; and dynamical chiral symmetry breaking (DCSB), which is a remarkably effective mass generating mechanism, responsible for the mass of more than 98% of visible matter in the Universe. These phenomena are not apparent in the formulae that define QCD, yet they play a principal role in determining Nature's observable characteristics. Much remains to be learnt before confinement can properly be understood. On the other hand,the last decade has seen important progress in the use of relativistic quantum field theory, so that we can now explain the origin of DCSB and are beginning to demonstrate its far-reaching consequences. Dyson-Schwinger equations have played a critical role in these advances. These lecture notes provide an introduction to Dyson-Schwinger equations (DSEs), QCD and hadron physics, and illustrate the use of DSEs to predict phenomena that are truly observable.2010 Mathematics Subject Classification: 81Q40, 81T16, 81T18

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From the nucleus to the quarks

Cited by 3 publications

References 14 publications

Nucleon and Roper electromagnetic elastic and transition form factors

Nucleon and Roper electromagnetic elastic and transition form factors

Collective Perspective on Advances in Dyson—Schwinger Equation QCD

Strong QCD and Dyson–Schwinger equations

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