摘要:

I discuss recent results of inclusive and exclusive electroproduction experiments at Jefferson Lab. They include measurements of the spin response for protons and neutrons in the resonance region, exclusive single pion and multiple pion production to measure resonance transition multipoles, and searches for missing quark model states. A brief outlook to the new domain of Generalized Parton Distributions is given as well. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436585

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We report on recent progress achieved in calculating various few-nucleon low-energy observables from effective field theory. Our discussion includes scattering and bound states in the2N,3Nand4Nsystems and isospin violating effects in the2Nsystem. We also establish a link between the nucleon-nucleon potential derived in chiral effective field theory and various modern high-precision potentials. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436586

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The pion-production reaction&pgr;+A→&pgr;+&pgr;±A′as a function ofAandThas been studied with the CHAOS spectrometer at the TRIUMF meson facility. Charged pion pairs have been detected in coincidence to ensure a unique identification of&pgr;+&pgr;±events. The&pgr;+&pgr;−invariant massM&pgr;+&pgr;−Ahas been found to peak increasingly toward the2m&pgr;threshold as the nucleus mass number increases, while theM&pgr;+&pgr;+Ayield shows a negligible A-dependence near threshold. The&pgr;+&pgr;−pairs have been found to predominantly couple toS-wave, i.e.,J=0.Theoretical works on the(&pgr;&pgr;)I=J=0interaction in nuclear matter, have shown that such enhancement is the combined effect of standard many-body correlations and the restoration of chiral symmetry in nuclear matter, i.e., the appearance of the &sgr;-meson. New data for the pion-production reaction on45Scat three incident kinetic energies (240, 280, 300 MeV) have been analyzed and preliminary results are presented. The results for45Scat 280 MeV are compared with the40Caresults, previously published by the CHAOS collaboration. The45Scresults at different energies highlight theT-dependence of the &pgr;&pgr; interaction in nuclear matter. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436587

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Progress in the Effective Field Theory of two and three nucleon systems is sketched, concentrating mainly on the low energy version in which pions are integrated out as explicit degrees of freedom. Examples given are: the extraction of nucleon polarisabilities from deuteron Compton scattering at very low energies; the energy dependence of the nucleon polarisabilities; three body forces and the triton; andndpartial waves at momenta below the pion cut. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436588

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We review some recent results for elastic electron deuteron scattering (deuteron form factors) and photodisintegration of the deuteron, with emphasis on the recent high energy data from Jefferson Laboratory (JLab). ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436589

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

High resolution spectroscopy of light hypernuclei has been carried out with a newly constructed Ge detector calledHyperball. The fine structure of hypernuclei due to the &Lgr;-N spin-spin and spin-orbit interaction were clearly observed for&Lgr;7Liand&Lgr;9Be.We will discuss these results and current status of the on-going experiment at BNL. Recent observation of a double hypernuleus,Lambpha(&Lgr;&Lgr;6He),at KEK has a great impact on the study ofS=−2nuclei. The result is presented and further important questions aboutS=−2nuclei are discussed. We will also briefly describe the present status of the high intensity proton accelerator (JHF) being constructed by KEK-JAERI in Tokai. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436590

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The framework of point form relativistic quantum mechanics is used to calculate elastic deuteron and nucleon form factors. Deuteron wave functions from Argonne&ngr;18and Reid’93 potentials are used in conjunction with form factors for the proton and neutron in the point form spectator approximation. For the nucleon form factors wave functions from the Goldstone Boson Exchange model with pointlike constituent quarks and no anomalous magnetic moment give very good fits to the data. Point form electrodynamics is used to show how to construct few-body current operators, needed to improve the fit with data for the deuteron form factors. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436591

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The present status of our understanding of the electromagnetic structure of three-body nuclei and of proton radiative and weak capture on deuteron and3Heis here reviewed, in the framework of the standard nuclear physics approach. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436592

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We detail the various steps needed to calculate physical observables involving relativistic bound states, as formulated in Light-Front Dynamics (LFD). We emphasize in this context the advantages of a covariant formulation of LFD in order, first, to define a bound state of given angular momentumJon the light-front, and, second, to calculate its properties as revealed for instance by electron scattering. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436593

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We discuss some basic aspects of searching for a three-nucleon force, and describe an experimental program at the Indiana Cooler to measure analyzing powers and spin correlation coefficients inpdscattering at 135 and 200 MeV proton energy. The experiment makes use of the PINTEX internal target facility, which was recently upgraded to provide a vector- or tensor-polarized deuterium target. Preliminary results for a number of polarization observables are in qualitative agreement with Faddeev calculations. Including a three-nucleon force in the calculation tends to alleviate the remaining discrepancies. Future plans forpdbreak-up measurements are discussed. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1436594

出版商:AIP    

年代:1901

数据来源: AIP