摘要:

We review recent developments in lattice QCD calculations of the light hadron spectrum and quark masses. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482451

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Our current knowledge about glueballs and hybrid mesons from lattice QCD simulations is briefly reviewed. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482452

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Hybrid adiabatic potentials are considered in the framework of the QCD string model. The einbein field formalism is applied to obtain the large‐distance behaviour of adiabatic potentials. The calculated excitation curves are shown to be the result of interplay between potential‐type longitudinal and string‐type transverse vibrations. The results are compared with recent lattice data. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482453

出版商:AIP    

年代:1902

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.1482454

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Pythagoreanism, as derived from the physics of music, an artificial quantized system, involved simple ratios between integers and was conjectured by the Pythagoreans to extend to the whole of physics (the Music of the Spheres). It hit the jackpot in 1895 with Balmer’s formula and has dominated XXth Century physics, with its Quantum Foundations. I review the history of Hadron Spectroscopy and my personal role in 1958–1964, i.e. (1) my 1960 discovery of SU(3) symmetry with an octet assignment for thej = 12baryons (independently reached somewhat later by M. Gell‐Mann), and (2) in 1961 (with H. Goldberg) my mathematical construction of a structural model which was then developed into the physical quark model by Gell‐Mann and Zweig. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482455

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The investigation of the excitation spectrum of nucleons provides important information on many open questions in baryon spectroscopy. The key to any progress is the identification of the effective degrees of freedom leading to a qualitative understanding of strong QCD. The problem ofmissing resonancespredicted by quark models and the nature of the nucleon resonance S11(1535) is discussed on the basis of recent experimental results of the CB‐ELSA experiment at the e−accelerator ELSA in Bonn. Among other things, the data show clear structures due to high‐mass resonance production. Successive decays via &Dgr;(1232)&pgr; are observed. The study of symmetries among negative‐parity baryons allows predictions of &Dgr;*decay properties and, therefore, will shed some light on the rather unknown &Dgr; spectrum. At present, QCD does not account for quark confinement. However, flavor symmetry seems to play a striking role in the confinement of three quarks. This is well observed for the first (u,d) quark family and predictions are also made for the second family (s). Open questions remain as to what the role of the gluon is, for instance. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482456

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

It is interesting that the fields of meson and baryon spectroscopy have taken divergent paths in the last decade. It is time the fields were more aware of the similarities and this author hopes the fields will benefit from each other’s accomplishments. This note will point out the similarities and the differences. Sometimes, the differences are in nomenclature. However, there are also practical reasons for the divergences. The typical meson experiment has a more complicated final state than baryon experiments and the most complete theoretical treatments limit the number of final state particles to three. There are also important differences in sociology. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482457

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The Crystal Ball Spectrometer is being used at the Brookhaven National Laboratory Alternating Gradient Synchrotron in a series of experiments that study final states of &pgr;−p andK−p induced reactions that result in all neutral particles. Data have been obtained on the decays ofN*, &Dgr;, &lgr;, and &Sgr; resonances. Threshold &eegr; production has been studied in detail for both &pgr;−p andK−p. Sequential resonance decays have been studied by studying the2&pgr;oproduction mechanism both in the fundamental interaction and in nuclei. In addition, we have used the &eegr;s produced near threshold to make precision measurements searching in particular for rare and forbidden &eegr; decays. The new limits on branching ratios provide stringent constraints on current theoretical models. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482458

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

J/&psgr; attenuation is considered to be one of the best tell‐tale signatures of Quark‐Gluon Plasma which is expected to be formed in the collision of relativistic heavy ions. In order to make sure that the observedJ/&psgr; attenuation does not have other, more benign, explanations, it is necessary to measureJ/&psgr;‐Nucleon absorption cross section. It is proposed that the best way to do so is to studyJ/&psgr; formation in the annihilation of antiprotons with nuclear protons. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482459

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

It is pointed out that the hadron spectroscopy should be a study of the structure of the QCD vacuum, low‐energy elementary excitations on top of which are hadrons. Concentrating on the dynamical breaking of the chiral symmetry in the QCD vacuum, we emphasize the importance to clarify what is going on with mesons in theI=J= 0‐channel, i.e., the sigma meson channel, because it is connected to the quantum fluctuations of the chiral order parameter. After summarizing the significance of the sigma meson in QCD and low‐energy hadron phenomenology, we give a review on some theoretical and experimental effort to try to reveal the possible restoration of chiral symmetry in hot and dense nuclear matter including heavy nuclei. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482460

出版商:AIP    

年代:1902

数据来源: AIP