共查询到20条相似文献,搜索用时 19 毫秒
1.
Two experiments on the production of the a
0
+ (980)-resonance in the reaction
were performed with the ANKE spectrometer at COSY-Jülich. The decay channels
and
were measured simultaneously at energies T = 2.65 GeV and T = 2.83 GeV. For the reaction
a total production cross-section of
nb has been deduced for T = 2.65 GeV. Further goals of the data analysis are to determine differential cross-sections like angular distributions and the branching ratio
.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.75.Cs Nucleon-nucleon interactions (including antinucleons, deuterons, etc.) - 25.40.Ve Other reactions above meson production thresholds (energies > 400 MeV)P. Fedorets: For the ANKE Collaboration: Complete collaboration list available via: http: //www.fz-juelich.de/ikp/ankeV. Kleber: For the ANKE Collaboration: Complete collaboration list available via: http: //www.fz-juelich.de/ikp/anke 相似文献
2.
The results of the experiment performed by the Belle Collaboration and aimed at observing the f 0(980) resonance in the reaction γγ → π + π ? are analyzed. It is indicated that these results suggest the presence of mechanisms in this reaction that lead to a strong distortion of the f 0(980)-resonance line shape in relation to the line shape expected for a solitary Breit-Wigner resonance. It is shown that the K + K ?-loop mechanism of f 0(980) coupling to the γγ system and the destructive interference between the background and f 0(980)-resonance contributions in the region of the π + π ? invariant mass below the K + K ? threshold are the main factors responsible for the formation of a specific (stepwise) f 0(980)-resonance line shape in the cross section for the reaction γγ → π + π ?. 相似文献
3.
In this proceeding,we propose to directly measure the a00(980)-f0(980)mixing in J/ψ→φ f0(980)φa00(980)and χc1 →π0a00(980)→π0f0(980)with the upgraded Beijing Electron Positron Collider(BEPCII)with BESⅢ detector.We show that a narrow peak of about 8 MeV will be produced by the a00(980)-f0(980)mixing,and the predominant feature makes it standing out from the background contributions.The predicted branching ratios for these two reactions are both expected to be about O(10-6),which is unambiguously accessible with109 J/ψ and 3 × 108 χc1 at BESⅢ. 相似文献
4.
f
0(980) and a
0(980) resonances near the thresholds of the γγ → K
+
K
− and γγ → K
0
K̇
0 reactions
High-statistical data on the γγ → K + K ? and γγ → K 0 K? 0 reactions constitute the last missing link in investigations of light scalar mesons f 0(980) and a 0(980) in photon-photon collisions. It is expected that the manifestation of the four-quark structure of the f 0(980) and a 0(980) resonances in these reactions will be very peculiar. The possibilities of the observation of scalar contributions in the γγ → K + K ? and γγ → K 0 K? 0 reactions near their thresholds at modern colliders have been estimated. 相似文献
5.
6.
We consider the problem of mixing in the f
0(980)–a
0(980) system when width effects are taken into account. By explicit calculation we show that two mixing angles are necessary to describe the phenomenon. 相似文献
7.
8.
9.
D.V. Bugg 《The European Physical Journal C - Particles and Fields》2006,47(1):57-64
Ratios of coupling constants for these decays are compared with qq̄ predictions and Jaffe’s q2q̄2 model. In both models, the predicted ratio g2(κ→Kπ)/g2(σ→ππ) is much too small. Also, for qq̄, the predicted ratio g2(κ→Kη’)/g2(κ→Kπ) is much larger than observed. Both models fail for g2(f0→KK)/g2(a0→KK). This ratio requires that f0 has a dominant KK component. It arises naturally because the f0 pole lies very close to the KK threshold, giving its wave function a long KK tail.
PACS 13.25.Gv, 14.40.Gx, 13.40.Hq 相似文献
10.
The K+ and K0 meson mass difference induces the mixing of the a(0)(0)(980) and f(0)(980) resonances, the amplitude of which, between the K+K- and K0(-)K(0) thresholds, is large in magnitude, of the order of m(K)m(2)(K0)sqrt[-m(2)(K+)] approximately sqrt[alpha] m(2)(K), and possesses the phase sharply varying by about 90 degrees. We suggest performing the polarized target experiments on the reaction pi(-)p-->etapi(0)n at high energy in which the fact of the existence of a(0)(0)(980)-f(0)(980) mixing can be unambiguously and very easily established through the presence of a strong jump in the azimuthal asymmetry of the etapi(0) S wave production cross section near the K(-)K thresholds. The presented estimates of the polarization effect to be expected in experiment are to a great extent model independent. 相似文献
11.
N. N. Achasov 《Physics of Atomic Nuclei》2002,65(3):546-551
A critical consideration of all unusual properties of the scalar a 0(980) and f 0(980) mesons is presented within the four-quark, two-quark, and molecular models. Arguments in favor of the four-quark model are given. Further experiments that could finally resolve this issue are discussed. 相似文献
12.
Balestra F Bedfer Y Bertini R Bland LC Brenschede A Brochard F Bussa MP Choi S Colantoni ML Dressler R Dzemidzic M Faivre JC Ferrero A Ferrero L Foryciarz J Fröhlich I Frolov V Garfagnini R Grasso A Heinz S Jacobs WW Kühn W Maggiora A Maggiora M Manara A Panzieri D Pfaff HW Piragino G Popov A Ritman J Salabura P Tchalyshev V Tosello F Vigdor SE Zosi G;DISTO Collaboration 《Physical review letters》2002,89(9):092001
Total and differential cross sections for the exclusive reaction pp-->pp rho observed via the pi(+)pi(-) decay channel have been measured at p(beam)=3.67 GeV/c. The observed total meson production cross section is determined to be (23.4+/-0.8+/-8) mu b and is significantly lower than typical cross sections used in model calculations for heavy-ion collisions. The differential cross sections measured indicate a strong anisotropy (approximately cos(theta(CM)(rho)) in the rho(0) meson production. 相似文献
13.
A. Dzyuba V. Kleber M. Büscher V. P. Chernyshev S. Dymov P. Fedorets V. Grishina C. Hanhart M. Hartmann V. Hejny L. Kondratyuk V. Koptev P. Kulessa Y. Maeda T. Mersmann S. Mikirtychyants M. Nekipelov D. Prasuhn R. Schleichert A. Sibirtsev H. J. Stein H. Ströher I. Zychor 《The European Physical Journal A - Hadrons and Nuclei》2006,29(2):245-251
The reaction pp → dK
+ˉ has been investigated at excess energies Q = 47.4 and 104.7MeV above the K
+ˉ threshold at COSY Jülich. Coincident dK+ pairs were detected with the ANKE spectrometer, and subsequently ∼ 2000 events with a missing ˉ invariant mass were identified,
which fully populate the Dalitz plot. The joint analysis of invariant mass and angular distributions reveals s-wave dominance between the two kaons, in conjunction with a p-wave between the deuteron and the kaon pair, i.e.
Kˉ production via the a
0
+(980) channel. Integration of the differential distributions yields total cross-sections of σ(pp → dK
+ˉ) = (38±2stat±14syst)nb and (190±4stat±39syst)nb for the low and high Q value, respectively. 相似文献
14.
《Physics letters. [Part B]》1988,207(2):115-120
A ππ and KK̄ coupled channels scheme, with separable s wave interaction, allows to discuss, from a hadronic point of view, some properties of the f0(975) meson. An intriguing case where the weak binding and narrow width are crucially related to the coupling of the channels leads to some interesting consequences for the f0(975) production in nuclear matter. 相似文献
15.
We calculate the radiative decay widths of the a
0(980) and f
0(980) scalar mesons into ργ and ωγ considering the dynamically generated nature of these scalar resonances within the realm
of the chiral unitary approach. The main ingredient in the evaluation of the radiative width of the scalar mesons are the
loops coming from the decay into their constituent pseudoscalar-pseudoscalar components and the subsequent radiation of the
photon. The dominant diagrams with only pseudoscalar mesons in the loops are found to be convergent while the divergence of
those with a vector meson in the loop are written in terms of the two-meson loop function easily regularizable. We provide
results for all the possible charge channels and obtain results, with uncertainties, which differ significantly from quark
loops models and some version of vector meson dominance. 相似文献
16.
轻标量介子性质研究是当今中高能核物理研究中的热点问题之一,特别是质量低于1 GeV的标量介子f0(980)的内部结构一直存在争议,至今未达成共识。基于前人的研究结果,运用有效拉氏量方法,对f0(980)粒子的光生过程γp→pf0(980)进行了更深入的理论研究。探讨了两种传播子形式下得矢量介子ρ和ω交换的贡献,第一种是选择雷吉传播子,第二种是选择普通费曼传播子。第二种形式的微分散射截面理论结果与现有实验数据符合比第一种形式的结果好。基于此,计算了两种形式的总截面,两种形式给出的理论结果相差很大。另外,给出了γp→pf0(980)→pπ+π-过程的π+π-不变质量分布的理论预言,发现π+π-不变质量分布对于f0(980)于K-K的耦合常数(gf0KK)有很强的依赖关系,不同的gf0KK给出明显不同的π+π-不变质量分布。将来相关实验数据可以验证这些理论预言,并对矢量介子传播子形式和耦合常数gf0KK做出限制,加深人们对f0(980)粒子的认识。We study the scalar meson f0(980) in the γp→pf0(980) reaction within an effective Lagrangian approach. Based on previous studies, we calculate the differential cross sections of this reaction. We take two types of the propagators of vector mesons ρ and ω, one is the Regge form, the other one is the normal Feynman propagator. It is found that our theoretical results for the differential cross sections with the Feynman propagator are in agreement with the current experimental data. For the total cross sections, the results with the two types of propagator are much different. On the other hand, we predict the π+π- invariant mass distribution of the γp→pf0(980)→pπ+π- reaction. We find that the π+π- invariant mass distribution depends sensitively on the value of the coupling constant gf0KK. We hope that the future experiments can test our model calculation and give further constraints on the value of gf0KK and also the nature of f0(980). 相似文献
17.
W. K. Eyrich 《Progress in Particle and Nuclear Physics》2003,50(2):547-555
The K-meson production in elementary proton induced reactions is studied exclusively at the external COSY beam using the time-of-flight spectrometer TOF. The complete measurement of all primary and decay particle tracks allows the extraction of total and differential cross sections as well as Dalitz plots and invariant mass spectra of the subsystems for the channels pp → K+ Δp, K0Σ+p, K+Σ0p and K+Σ+n. For all channels the full phase space is covered from the reaction threshold up to the COSY-limit of about 3.5 GeV/c. Especially the analysis of the Dalitz plots of the channel pp→K+Δp show a strong influence of N−* resonances. 相似文献
18.
19.
In this article, we take the point of view that the scalar mesons f0(980) and a0(980) are the diquark-antidiquark states
, and we devote our attention to the determination of their masses in the framework of the QCD sum rule approach with the interpolating currents constructed from scalar-scalar type and pseudoscalar-pseudoscalar type diquark pairs respectively. The numerical results indicate that the scalar mesons f0(980) and a0(980) may have two possible diquark-antidiquark substructures.Received: 27 January 2005, Revised: 22 March 2005, Published online: 31 May 2005PACS:
12.38.Lg; 13.25.Jx; 14.40.Cs 相似文献