On the determination of the π<sup>3</sup>He<sup>3</sup>He coupling on the basis of PCAC

Dumbrājs, O.

doi:10.1088/0305-4616/6/1/003

Cited by 65 publications

(107 citation statements)

References 8 publications

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“…There are two sources of information on the value of g,sNN. The first comes from N N scattering phase shift analysis within the framework of the one-boson-exchange potential (OBEP) model [34]. It gives ggeNN=7.3 with presumably a large error.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Quark and gluon content of the proton spin

1991

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We examine the role of quarks and gluons in polarized deep-inelastic scattering in connection with the famous European Muon Collaboration experimental result. The gluon contribution generated by the axial anomaly is shown to have a well-defined physical meaning and its gauge-invariance properties are fully clarified. We also emphasize the role of the ghost contribution in the generalized Goldberger-Treiman relation and give a detailed calculation of the correction due to unequal quark masses and to aO-77-77' mixing.

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Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Quark and gluon content of the proton spin

1991

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“…For example, a determination of g η ′ N N using F, D and θ 3 values gives g η ′ N N = 3.4 [159] whereas an estimate of the η ′ → 2γ decay rate through the baryon triangle contributions yields g η ′ N N = 6.3 [72]. The analysis of the NN potential gives g η ′ N N = 7.3 [208] while the forward NN scattering analyzed by dispersion relations gives g η ′ N N < 3 [124]. On the other hand, the only chance to determine g GN N is from the polarized DIS data via the U(1) GT relation.…”

Section: Nonperturbative Approaches To the Proton Spinmentioning

confidence: 99%

Spin physics and polarized structure functions

2000

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A review on the theoretical aspects and the experimental results of polarized deep inelastic scattering and of other hard scattering processes is presented. The longitudinally polarized structure functions are introduced and cross section fromulae are given for the case of photon as well as W ± and Z 0 exchange. Results from the SLAC and CERN polarization experiments are shown and compared with each other as well as their implications for the integrated g 1 (x, Q 2 ) are reviewed. More recent experiments presently underway (like HERMES at DESY) and future projects (like RHIC at BNL, HERA-N and a polarized HERA collider at DESY) are discussed too. The QCD interpretation and the LO and NLO Q 2 -evolution of g 1 , i.e. of the longitudinally polarized parton densities, is discussed in great detail, in particular the role of the polarized gluon density, as well as the expectations for x → 0. Particular emphasis is placed on the first moment of the polarized structure function in various factorization schemes, which is related to the axial anomaly, and on its relevance for understanding the origin of the proton spin. Sum rules (i.e. relations between moments of the structure functions) are derived and compared with recent experimental results. Various other phenomenological applications are discussed as well, in particular the parametrizations of polarized parton densities as obtained from recent data and their evolution in Q 2 . Furthermore, jet, heavy quark and direct photon production are reviewed as a sensitive probe of the polarized gluon density, and the physics prospects of the future polarized experiments at RHIC ( p p) and a polarized HERA collider ( e p) are studied. DIS semi-inclusive asymmetries and elastic neutrino-proton scattering are reviewed, which will help to disentangle the various polarized flavor densities in the nucleon. The status of single and double spin asymmetries, and the observation of handedness in the final state, are discussed as well. Structure 1 functions for higher spin hadrons and nuclei are defined and possible nuclear effects on high energy spin physics are reviewed. The theoretical concept of spin-dependent parton distributions and structure functions of the polarized photon is presented and possibilities for measuring them are briefly discussed. Various nonperturbative approaches to understand the origin of the proton spin are reviewed, such as the isosinglet U A (1) Goldberger-Treiman relation, lattice calculations and the chiral soliton model of the nucleon. The physical interpretation and model calculations of the transverse structure function g 2 are presented, as well as recent twist-3 measurements thereof, and the Burkhardt-Cottingham sum rule is revisited. Finally, the physics of chiral-odd 'transversity' distributions is described and experimental possibilities for delineating them are reviewed, which will be important for a complete understanding of the leading twist-2 sector of the nucleon's parton structure. In the Appendix the full 2-loop anomalous dimension...

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“…The contribution of the omega graph to the photoproduction of pions or eta mesons is small, so that the ωNN coupling constants cannot be determined by fitting the experimental data for these processes [21,22]. Instead, they are taken from NN scattering [23], or they are derived from the ρNN parameters via SU(3) considerations [24]. The values for g v ωNN used in the literature for photoproduction processes range from 8 [24] to 17 [25].…”

Section: A the Elementary Operatormentioning

confidence: 99%

Coherent photoproduction of pions on spin-zero nuclei in a relativistic, non-local model

1998

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A relativistic and non-local model for the coherent photoproduction of pions on spin-zero nuclei is presented. The production operator is derived from an effective Lagrangian model that contains all the degrees of freedom known to contribute to the elementary process. Using the framework of DWIA, the matrix elements of this operator are evaluated using relativistic bound state wave functions. Final state interactions are accounted for via a pion-nucleus optical potential. The effects of in-medium modifications of the production operator are discussed. We give results for 12 C and 40 Ca, and compare our calculations to the data of the A2 collaboration at MAMI.

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On the determination of the π³He³He coupling on the basis of PCAC

Cited by 65 publications

References 8 publications

Quark and gluon content of the proton spin

Quark and gluon content of the proton spin

Spin physics and polarized structure functions

Coherent photoproduction of pions on spin-zero nuclei in a relativistic, non-local model

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On the determination of the π3He3He coupling on the basis of PCAC

Cited by 65 publications

References 8 publications

Quark and gluon content of the proton spin

Quark and gluon content of the proton spin

Spin physics and polarized structure functions

Coherent photoproduction of pions on spin-zero nuclei in a relativistic, non-local model

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Product

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On the determination of the π³He³He coupling on the basis of PCAC