摘要:

We review the present relativistic mean field theory from the view point of missing the contributions of pions. We discuss then the role played by pions for hadrons and light nuclei. We introduce the interesting experimental data on pionic states taken at RCNP. These data seem to suggest the occurrence of pion condensation in the nuclear surface. Qualitative discussion is made on the consequence of surface pion condensation on Gamow-Teller transitions and spin response functions and others. We demonstrate that the spin-isospin projection from the surface pion condensed intrinsic state extracts as the dominant term the 2p-2h states connected with 0p-0h state by the tensor force. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425482

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Results of a combined analysis are presented for the production of &ohgr; and &fgr; mesons in&pgr;Nreactions in the near-threshold region using throughout a conventional “non-strange” dynamics based on such processes which are allowed by the non-ideal &ohgr;-&fgr; mixing. We find a strong difference between observables in &ohgr; and &fgr; production reactions caused by the different role of the nucleon and nucleon resonance amplitudes. A series of predictions for the experimental study of this effect is shown. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425483

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

After a brief introduction about the antinucleon-nucleus interaction, the results of the OBELIX experiment concerning the annihilation cross section will be discussed in the frame of the data presently available in literature. Then the preliminary data concerning the final state of the annihilation, in particular the spectra, the multiplicities and the signal of the &rgr;-meson are presented. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425484

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The new giant dipole state excited by exchange current is investigated. While the well-known giant dipole resonance state is described as an oscillation of protons against the neutrons, the new one is composed of two giant resonance states as[0+(T=1)×1−(T=1)]1−(T=1,Tz=0)or[1−(T=1)×2+(T=1)]1−(T=1,Tz=0).These double giant resonance states may be observed experimentally in(&ggr;,pn),(e,e′pn),or (&pgr;,&pgr;). ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425485

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We study the structure and formation of the deeply bound pionic states theoretically. These states have attracted much attention since they provide us with valuable information on the behavior of “real” pions in the interior of the nucleus. In this paper, we briefly summarize the history of the research and, as one of the current activities, we show the isotope dependence of deeply bound pionic states in Sn and Pb isotopes. It is shown the isotope effects can be observed from the data of(d,&hthinsp;3He)reactions with accessible energy resolution. The isotope dependence are expected to provide us new information on the pion-nucleus isovector interaction and/or the neutron density distributions of nuclei. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425486

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Chiral symmetry of baryons is studied by identifying them with linear representations of the chiral symmetry group. We show that two distinctive chiral assignments are possible. Based on these two assignments, linear sigma models are constructed and their physical implications are studied. Then we propose experiments to observe the relative sign of axial charges of the positive and negative parity nucleons through the &pgr; and &eegr; productions at the threshold region. This can be used as a probe to distinguish the two chiral assignments. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425487

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We address the question if one can empirically distinguish between the two proposed solutions to the “UA(1)problem:” the ’t Hooft, and the Veneziano-WittenUA(1)symmetry breaking effective interactions. Two hadronic observables are offered as discriminants: (1) The scalar(0+)meson spectrum; (2) Weinberg’s second spectral sum rule. Their present experimental status is discussed. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425488

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Electromagnetic meson production formalisms are reviewed, with emphasise placed on their ability in search for new baryon resonancesvia&ggr;p→K+&Lgr;and&ggr;p→&eegr;pprocesses. The relevant studies, aiming to deepen our insights to hadron spectroscopy, constitute strong tests of the QCD inspired theoretical developments. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425489

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The Continuous Electron Accelerator Facility, CEBAF, is devoted to the investigation of the electromagnetic structure of mesons, nucleons, and nuclei using high-energy and high duty-cycle electron and photon beams. The physics program and the experimental equipment at CEBAF will be described. Selected examples for the results obtained will be given. The motivation for upgrading the accelerator to higher energy will be discussed. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425490

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The Laser-Electron-Photon facility at SPring-8 (LEPS) is now taking data for all hadronic reactions at compton-backscattered photon energies between 1.5 GeV and 2.4 GeV. A linearly polarized photon beam is incident on a liquid hydrogen target or nuclear targets. A large dipole spectrometer analyzes charged particles produced at forward angles. First results from SPring-8/LEPS will be presented with special emphasis on the study of photoproduction of &fgr; mesons near threshold. Some prospects for the near future will also be presented and discussed in close connection with photoproduction of hyperons. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1425491

出版商:AIP    

年代:1901

数据来源: AIP