摘要:

We study interference patterns in the &fgr; → (&ggr;a0+ &pgr;0&rgr;) → &ggr;&pgr;&eegr; and &fgr; → (&ggr;f0+ &pgr;0&rgr;) → &ggr;&pgr;0&pgr;0reactions. Taking into account the interference, we fit the experimental data and show that the background reaction does not distort the &pgr;0&eegr; spectrum in the decay &fgr; → &ggr;&pgr;&eegr; everywhere over the energy region and does not distort the &pgr;0&pgr;0spectrum in the decay &fgr; → &ggr;&pgr;0&pgr;0when the invariant massm&pgr;0&pgr;0> 670 MeV. We discuss the details of the scalar meson production in the radiative decays and note that there are conclusive arguments in favor of the one‐loop mechanism &fgr; →K+K−→ &ggr;a0(or &ggr;f0). We discuss also distinctions between the four‐quark, molecular, and two‐quark models and argue that the establishment of the scalar meson production mechanism in the &fgr; radiative decays gives new strong evidence in favor of the four‐quark nature of the scalara0(980) andf0(980) mesons. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482441

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

First preliminary results from upgraded SPHINX spectrometer, working in the proton beam with the energy of 70 GeV of IHEP accelerator, are presented. The data for the reactionp+N→ [&Sgr;0K+] +Nbased on a new statistics are in a good agreement with our previous data and strongly supports the existence of X(2000) state (with the increase of statistics for this state by a factor of ∼ 5). We also observed radiative decay of &Lgr;(1520) → &Lgr; + &ggr;. The significant increase of statistics for many diffractive production reactions will allow us to study them in great detail. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482442

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Experiment E852 at Brookhaven National Laboratory is an experiment in meson spectroscopy configured to detect both neutral and charged final states of &pgr;−pcollisions at 18 GeV/c. The main goal of this experiment is to search for the signs of mesons which cannot be described in the scope of the constituent quark model, with an emphasis on the meson with the manifestly exotic quantum numbers. In this talk the description of the experimental apparatus along with a general overview of the latest E852 results are presented. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482443

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We present preliminary results of study of the &eegr;&pgr;−, &eegr;′&pgr;−andb1&pgr;‐systems produced in the &pgr;−Be‐interaction at 28GeV/c.JPC= 2++and 1−+‐waves resulted from the PWA have been fitted in each system separately to establish the nature of the 1−+‐wave. A hypothesis of the 1−+‐wave resonant nature in the &eegr;&pgr;−and &eegr;′&pgr;−has no statistically significant preference over the non‐resonant one. Theb1&pgr;‐system analysis confirms the results of the 37GeV/c‐beam data analysis in favor of the resonant treatment of the bump at 1.6GeV. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482444

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Experimental data (∼ 40000KSKSevents and ∼ 2300 &Lgr;&Lgr;¯ events) were obtained on the ITEP 6‐meter spectrometer with a 40 GeV &pgr;−beam of the IHEP U‐70 accelerator. The experimental setup is being upgraded now. The analysis of the 1200–1300 MeV/c2effective mass region of theKSKS‐meson system was carried out for events obtained with the neutral trigger with 40 cm H2target. Irregularity near 1240 MeV/c2and width about 30 MeV/c2is clearly observed. Similar irregularity is observed on another sample of 15000 event on carbon target. A resonance states with mass near 1800 MeV/c2and 2230 MeV/c2are observed at selection of cos&hthinsp;&thgr;GJ. The results of studying the &Lgr;&Lgr;¯ system produced in the reaction &pgr;−p→ &Lgr;&Lgr;¯nat a &pgr;−‐meson energy of 40 GeV are reported. The invariant‐mass spectra for the events dominated by the singlet or triplet &Lgr;&Lgr;¯ states were found to differ considerably from each other. The data give evidence for the existence of resonance states of the &Lgr;&Lgr;¯ system in the mass regions near 2.3, 2.5 and 2.8 GeV. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482445

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We discuss the classification of the light scalar mesons with mass below 2 GeV intoqq¯nonets and glueballs. The information on production and decay of these states, in particular recent information on thef0(980),f0(400 – 1200) (or &sgr;(600)) andf0(1500) is considered. Although the data are not yet very precise the recent information is in favour of the previously developed scheme which includesf0(980),a0(980),K0*(1430),f0(1500) into the lightest scalar nonet. The glueball in this approach appears as broad object around 1 GeV. Alternative schemes find the glueball at somewhat higher mass or suggest his mixing withqq¯states spread over a similar mass range. We do not see sufficient evidence yet for a light scalar nonet below 1 GeV around a &sgr;(600) resonance. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482446

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We first briefly review a treatment of the scalars in meson meson scattering based on a non‐linear chiral Lagrangian, with unitarity implemented by a “local” modification of the scalar propagators. It is shown that the main results are confirmed by a treatment in the SU(3) linear sigma model in which unitarity is implemented “globally.” Some remarks are made on the speculative subject of the scalars’ quark structure. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482447

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Starting from the multi‐local Klein‐Gordon equations with Lorentz‐scalar squared‐mass operator we give a covariant quark representation of the general composite mesons and baryons with definite Lorentz transformation property. The mass spectra satisfy the approximate symmetry under theU˜(4) transformation group, including the chiral transformation as a subgroup, concerning the spinor freedom of light constituent quarks, and this symmetry predicts the existence of new type of chiral mesons and baryons out of the conventional framework in non‐relativistic quark model: For example, for lightqq¯systems, the scalar &sgr;‐ and axial‐vectora1‐nonets, and for heavy‐lightQq¯andqQ¯systems the scalar and axial‐vector mesons are predicted to exist as relativisticS‐wave states besides the ordinaryP‐wave state mesons. The existence of two “exotic” 1−+meson nonets is predicted as the relativisticP‐wave states inqq¯systems. For light quark baryons the extra56with positive parity and the extra70with negative parity of the staticSU(6) are predicted to exist as the ground state chiral particles. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482448

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Basing on the latest results of the PNPI (Gatchina) and QM&W College (London) groups, I discuss systematics of theIJPCqq¯states in terms of trajectories on the (n,M2) plane, wherenis the radial quantum number andMis its mass. In the scalar sector, which is the most interesting because of the presence of extra states with respect to theqq¯systematics, I discuss: 1) the results of theK‐matrix analysis of the spectra &pgr;&pgr;, &pgr;&pgr;&pgr;&pgr;,KK¯, &eegr;&eegr;, &eegr;&eegr;′, &pgr;&eegr; and characteristics of the resonances in the scalar sector, 2)qq¯‐nonet classification of scalar bare states, 3) accumulation of widths of theqq¯states by the glueball due to the overlapping off0‐resonances at 1200–1700 MeV, 4) systematics of scalarqq¯states, both bare states and resonances, on the (n,M2)‐plots, 5) constraints on the quark‐gluonium content of the resonancesf0(980),f0(1300),f0(1500),f0(1750), and the broad statef0(1420−70+150)from hadronic decays, 6) radiative decays of theP‐waveqq¯‐resonances: scalarsf0(980),a0(980), and tensor mesonsa2(1320),f2(1270),f2(1525). The analysis proves that in the scalar sector we face two exotic mesons: the light &sgr;‐meson,f0(450), and the broad statef0(1420−70+150), which is the descendant of the glueball. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482449

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Non‐exotic scalar‐meson resonances inS‐wave meson‐meson scattering are studied in the light of a unitarised Schro¨dinger model. The resulting poles in the scattering matrices, by analytical continuation into the complex‐energy plane, are grouped into nonets of isoscalar, isodoublet, and isotriplet resonances. All singularities can be related toquark‐antiquark confinement states, the light‐quark nonet of which has ground states at 1.3 to 1.4 GeV and level spacings of some 300–400 MeV, except for a nonet of light scalar mesons below 1 GeV. All non‐exoticS‐wave resonances reported by experiment fit into this scheme. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1482450

出版商:AIP    

年代:1902

数据来源: AIP