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本文引进qiqi→qjqj以及qiqi→(gg)湮没项[1],并考虑了对湮没项的SU(3)破坏效应[2],讨论了η、η′和ι的混合,得到了它们的有声有色和胶子内容.与此同时,引入EPCAC(扩充的部分守恒赝矢流)假设[3],考察了η、η′和ι的双光子衰变.本文还计算了衰变宽度比R1=Γ(J/ψ→γη′)/Γ(J/ψ→γη)以及R2=Γ(J/ψ→γη′)/Γ(J/ψ→γι),指出了实验结果对纯胶子球质量值的限制. 相似文献
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在T2HDM模型中计算了中性希格斯粒子圈图对稀有衰变过程B→Xsl+l-的贡献. 通过计算发现: (a)中性希格斯粒子对衰变过程B→Xsl+l-的修正能够增强其标准模型的预言, 但增幅很小; (b)在中性希格斯玻色子的质量大于100GeV和tanβ<40的情况下, 中性希格斯粒子对稀有衰变过程B→Xsl+l-的分支比的贡献可忽略. 相似文献
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本文给出了级联衰变过程e++e-→J/ψ→V+X,X→P1+Y,Y→P2+P3(V代表矢量介子,Pi代表赝标介子)的角分布螺旋度形式,为通过J/ψ三级二体强衰变过程对中间态X粒子进行自旋-宇称分析提供理论公式. 相似文献
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本文用推广的矩分析方法对J/ψ的强衰变过程J/ψ→V1,X→V2+V3,V2、V3→2P或3P(其中Vi代表有质量的矢量粒子,P代表赝标介子)进行了讨论.对于具有不同自旋和宇称的中间态X,给出了相应的矩的表达式.在非相对论情况下,计算了过程X→V2+V3的螺旋度振幅值.通过比较部分矩的理论值和实验值,可以确定中间态粒子X的自旋、宇称和所处的分波态. 相似文献
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本文基于北京正负电子对撞机(BEPC)上北京谱仪(BES)所收集到的国家自然科学基金资助.7.8×106J/ψ事例,系统研究了J/ψ→φπ+π-和J/ψ→ωπ+π-两个衰变道,给出了过程的分支比以及f0的位置和宽度参数,并对J/ψ→φf0,f0→π+π-过程的角分布进行了拟合,首次确定出该过程的螺旋度振幅比. 相似文献
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Radiative meson decays are computed from quark loop anomalies, taking into account the SU(3) splitting of the quark masses. Predicted rates for ?→ηγ,K *→Kγ, and η→ππγ are brought into satisfactory agreement with experiment. Formulas are given for the radiative decay rates of charmed las are given for the radiative decay rates of charmed mesons, and a mechanism suggested for suppression of the radiative decays of mesons containing a charmed quark. 相似文献
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Combining the Okubo-Zweig-Iizuka rule in the decay φ→ρπ→π+π?π0 with the ρ→4π decay amplitudes, we calculate the φ→2π+2π?π0 and φ→π+π?3π0 ones. The partial widths of the above φ decays are evaluated, and the excitation curves in e+e? annihilation are obtained, assuming reasonable particular relations among the parameters characterizing the anomalous terms of the HLS Lagrangian. The evaluated branching ratios Bφ→π+π?3π0 ≈ 2 × 10?7 and Bφ→2π+2π?π0 ≈ 7 × 10?7 are such that, with the luminosity L=500 pb?1 attained at DAΦNE φ factory, one may already possess about 1685 events of the decays φ→5π. 相似文献
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In the extended NJL model the radiative decay widths of the radially excited states of the pseudo-scalar π, η, and η′ mesons are calculated. The predictions for the decay widths of the processes π(1300) → (ρ0, ω)γ, η(1295) → (ρ0, ω, φ)γ, and η(1475) → (ρ0, ω, φ)γ are given. Nowadays, there are no solid experimental data for these processes. The comparison of the results obtained in the framework of the standard and the extended NJL models for decays of the ground states of mesons is given. It is shown that these calculations correspond to each other and are also in satisfactory agreement with experimental data. This allows one to expect that the extended NJL can give reliable predictions for the excited states of mesons. 相似文献
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M. Araki 《Zeitschrift fur Physik C Particles and Fields》1986,31(1):121-128
It is shown that a mechanism, within the framework of the cloudy bag model, analogous to that fore + e ?→2ψ in QED accounts qualitatively for the decays ?→2π, ω→πψ and ?→πψ with a bag radii 0.8–1.0 fm, and averaged momenta for decay particles. For the radiative decays, the process identical to that in the vector-dominance model gives about 60% of the total calculated width. It also explains small decay widths previously calculated, using the single quark transition process. 相似文献
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《Nuclear Physics A》1998,632(1):153-170
Single photon spectra in heavy-ion collisions at SPS energies are studied in the relativistic transport model that incorporates self-consistently the change of hadron masses in dense matter. We separate the total photon spectrum into “background” arising from the radiative decays of π0 and η mesons, and the “thermal” one from other sources. For the latter we include contributions from radiative decays of ρ, ω, η′, and a1, radiative decays of baryon resonances, as well as two-body processes such as ππ → ργ and πρ → πγ. It is found that more than 95% of all photons come from the decays of π0 and η mesons, while the thermal photons account for less than 5% of the total photon yield. The thermal photon spectra in our calculations with either free or in-medium meson masses do not exceed the upper bound set by the experimental measurement of the WA80 Collaboration. 相似文献
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The effects on the meson mass spectrum of gluon interactions, and in particular of quark annihilation diagrams, are investigated in the current quark framework. The resulting mixing scheme leads to mixing angles θp ? ?13° and θV ? ? 52° for the pseudoscalar and vector nonets respectively, in moderate agreement with present data on radiative decays. For virtual electromagnetic processes additional gluon diagrams play a role. In η → 3π the net effect is to almost double the current algebra prediction, while in ω → 2π the ω → ?0 transition amplitude is correctly predicted in both sign and magnitude. The relation between the Hamiltonian approach and the U(1) problem, as formulated in terms of axial divergences, is briefly discussed. 相似文献
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Ya. I. Azimov 《Physics of Atomic Nuclei》2003,66(11):1989-1993
The influence of isospin-violating (ρ0, ω) mixing is discussed for any pair of decays of ρ0, ω into the same final state. It is demonstrated, in analogy to the CP violation in neutral kaon decays, that isospin violation can manifest itself in various forms: direct violation in amplitudes and/or violation due to mixing. In addition to the known decays (ρ0, ω) → π+π? and (ρ0, ω) → π0γ, the pair of decays to e+e? and the whole set of radiative decays with participation of ρ0, ω (in initial or final states) are also shown to be useful and promising for studies. Existing data on these decays agree with the universal character of the mixing parameter and indirectly support enhancement of ρ0 → π0γ in respect to ρ± → π±γ. Future precise measurements will allow one to separate different forms of isospin violation and elucidate their mechanisms. 相似文献
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S. F. Biagi M. Bourquin R. M. Brown H. J. Burckhart Ch. Doré P. Extermann M. Gailloud C. N. P. Gee W. M. Gibson R. J. Gray P. Jacot-Guillarmod P. W. Jeffreys W. C. Louis Th. Modis P. Mühlemann R. C. Owen J. Perrier K. J. S. Ragan Ph. Rosselet B. J. Saunders P. Schirato H. W. Siebert V. J. Smith K. -P. Streit J. J. Thresher R. Weill A. T. Wood C. Yanagisawa 《Zeitschrift fur Physik C Particles and Fields》1986,30(2):201-211
In an experiment performed at the CERN-SPS charged hyperon beam, we have observed the radiative decay Λ→nγ, using well identified Λ from the decays of Ο? of 116 GeV/c momentum. Neutrons and photons from the Λ decays were observed in liquid argon and lead glass detectors. From a sample of 31 candidates, containing an estimated background of 7.3 events, the decay branching ratio was measured to be Γ(Λ→nγ)/Γ(Λ→all)=(1.02±0.33)×10?3. 相似文献