摘要:

In order to assess the relevance of chiral dynamics in the scalar sector we address two recent problems: radiative decay of the &fgr;, for which there are quite recent data from Frascati, and the modification of the &sgr; properties in the nuclear medium seen through the &pgr;0&pgr;0photoproduction in nuclei. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632190

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The recent experimental data of both &pgr;&pgr;/&Kgr;&pgr; scattering and production processes, suggesting the existence of scalar &sgr; and &kgr; mesons, are reviewed. In many &pgr;&pgr;/&Kgr;&pgr; production processes the direct effects of their productions are observed, while they are, because of chiral symmetry, hidden in scattering processes, and now &sgr;(500∼600) and &kgr;(800∼900) are considered to be confirmed experimentally. Relation between &pgr;&pgr;/&Kgr;&pgr; production amplitudes and scattering amplitudes are considered. The long believed prejudice of universal &pgr;&pgr;/&Kgr;&pgr; phase through scattering and production amplitudes is explained to be not correct. Common fit of the production processes with the scattering phase shift is not valid, and the production processes should be independently analyzed from the scattering phase shift. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632191

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present a covariant approach to describe the low‐lying scalar, pseudoscalar, vector and axialvector mesons as quark‐antiquark bound states. This approach is based on an effective interaction modeling of the non‐perturbative structure of the gluon propagator that enters the quark Schwinger‐Dyson and meson Bethe‐Salpeter equations. We extract the meson masses and compute the pion and kaon decay constants. We obtain a quantitatively correct description for pions, kaons and vector mesons while the calculated spectra of scalar and axialvector mesons suggest that their structure is more complex than being quark‐antiquark bound states. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632192

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present a brief account of the developments in the description of light meson resonances using unitarized extensions of the Chiral Perturbation Theory series, both in energy and temperature. In particular, we describe how these methods have been recently shown to describe simultaneously the low energy and resonance regions of meson‐meson scattering. This approach could be of relevance to understand the light scalar mesons since it provides a formalism that respects chiral symmetry and unitarity and is able to generate resonant states without any a priori theoretical bias toward their existence, classification or spectroscopic nature. We will also review how this approach is also able to describe the thermal evolution of the &rgr; and &sgr; mesons. In addition we review their extensions to higher orders, the most recent determination of the resonance pole properties, as well as their behavior in the largeNclimit, which could be of relevance to understand their spectroscopic nature. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632193

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The advantages to study charge‐symmetry breaking and especially the phenomenon off0‐a0mixing in nucleon‐nucleon and deuteron‐deuteron induced reactions are discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632194

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We summarize some features of the vector meson dominance model which was recently proposed for studying radiative decays involving the scalar mesons. Using the experimental values of &Ggr;(a0→ &ggr;&ggr;), &Ggr;(f0→ &ggr;&ggr;) and &Ggr;(&fgr; →a0&ggr;) as inputs, we show that the model predicts a large hierarchy between &Ggr;(a0→ &ohgr;&ggr;) and &Ggr;(a0→ &rgr;&ggr;) as well as between &Ggr;(f0→ &ohgr;&ggr;) and &Ggr;(f0→ &rgr;&ggr;). © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632195

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We construct a3P0light‐front quark model wavefunction which is used to investigate various radiative scalar meson decays. Specifically, we look at decays involvingf0(1370),f0(1500), andf0(1710) which are assumed to be glueball—qq¯mixtures, as well asa0(980) andf0(980) which are assumed to beqq¯. Although our results for the scalar mesons above 1 GeV are not inconsistent with the available experimental data, the results for the mesons below 1 GeV are inconsistent with the data. This further supports the idea thata0(980) andf0(980) are not conventionalqq¯states. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632196

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The results of a model for meson‐meson scattering are studied. The model is shown to be capable of on the one hand reproducing the scattering data, while on the other hand a quark‐antiquark confinement spectrum can be determined. It is concluded that adopting the model’s formulation of the transition matrix elements for data analysis , it may serve as a link between experiment and quenched lattice calculations. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632197

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present a description of the low energy &pgr;&pgr; scattering data using the Linear Sigma Model with K‐matrix unitarization. Then we carry out an analogous study of the strongly‐coupled minimal Higgs sector of the electroweak theory. We discuss the effect of the unitarization prescription on the WW or ZZ fusion processes and also suggest a related treatment for other Higgs production processes such as gluon fusion. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632198

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We study the role of a light scalar nonet in the interesting decay &eegr; → 3&pgr;. The framework is a Chiral effective Lagrangian of pseudo‐scalars, scalars and vectors. At leading order , the scalars increase the predicted width by about 14&percent;. We note that although individual scalar contributions are not small, there are cancellations among the scalar diagrams. Including higher order symmetry breaking terms reduce the amount of cancellations among the scalar diagrams but the total predicted width remain the same. The vectors contribution is found to be very small. A preliminary discussion of the related decay &eegr;′ → 3&pgr; is given. We found that the leading order results of pseudo‐scalars alone are reasonable and close to the experimental data. Including the scalars or the vectors gives a huge enhancement indicating the importance of higher order corrections in this case. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1632199

出版商:AIP    

年代:1903

数据来源: AIP