共查询到20条相似文献,搜索用时 109 毫秒
1.
2.
本文讨论了新发现的重粒子γ(9.5)是SU(4)×S3a层子模型方案中介子的色激发态的可能性.指出在γ能区,应存在三个色激发基态,并且表现为质量约差0.5 GeV的两个峰.讨论了γ的轻子衰变、强衰变、辐射衰变、二级电磁强子型衰变的行为和γ的产生行为.还给出伴随γ在9.5 GeV能区还应存在许多介子色激发态,其中至少存在四个弱衰变粒子. 相似文献
3.
4.
本文引入一个统一的机制,试图解释J粒子的辐射衰变和G宇称守恒衰变到普通粒子的过程。这就是J先衰变到φn=αφ1+βφ8,然后由φn衰变到普通粒子。结果如下:1.φn≈ω最与实验相符,但给出的Γ(J→ω→ηγ)/Γ(J→ω→πγ)的理论值太小;2.为着定量谐调辐射衰变和二体强子衰变,要求这两类过程的形状因子相差三个数量级。本文从层子模型的图象出发,提出一个计算形状因子的简单模型。计算结果表明,上述形状因子的差别是可以解释的;3.本文还讨论了辐射衰变的另一种机制,并指出存在的问题。 相似文献
5.
本文从层子模型的基本假定出发,对介子和重子波函数进行了探讨。文中讨论了介子、重子这样的强耦合束缚态的物理特性,指出“层子对”的产生效应对波函数的贡献是重要的。文中给出了具有任意角动量的介子波函数的一般形式。在质心系中,假定介子波函数和重子波函数具有近似的SU6对称性质,得到了在质心系具有SU6对称性质的介子波函数和基态重子波函数的一般形式,禁戒了实验中不出现的介子态。在质心系假定了O3?SU6对称性,写下了在质心系具有这种对称性的几个低激发态重子的波函数。在每一个O3?SU6多重态中的介子和重子波函数都含有两个洛仑兹协变的空间函数,对强耦合的束缚态,由于“层子对”的产生效应是重要的,这两个不变函数一般是不相等的。由于只在质心系假定了SU6和O3?SU6对称,因而可以使波函数具有洛仑兹协变性,即运动系中这种对称性是不存在的。 相似文献
6.
从低能有效哈密顿及BSW方案出发,研究了企鹅图诱导的B介子两体非轻弱衰变过程中弱电企鹅图效应.通过计算发现,凡是涉及到外企鹅图的过程,弱电企鹅效应不可忽略,甚至占主导及统治地位. 相似文献
7.
在QCD光锥求和规则(LCSR)框架内应用具有手征流关联函数计算B(Bc)→Dlν衰变过程的弱形状因子. 所获得的形状因子的表达式仅依赖于D介子的主导级分布振幅(DA). 应用了三类D介子的分布振幅计算了形状因子FB→D(0)和FBc→D(0). 在速度迁移1.142=0附近算符乘积展开(OPE)得以有效的情况下所计算的形状因子行为在误差范围内与B(Bc)→Dlν过程实验数据相一致. 在大反冲区域1.35B→D(0)是与微扰QCD(pQCD)结果相一致的. 所以本文的计算在联接格点QCD, 重夸克对称性和pQCD之间起桥梁作用,有助于进一步对B(Bc)→Dlν跃迁过程的理解. 计算
使用了在端点具有指数压低的分布振幅行为, 对FBc→D(0)的预言与其他方法获得的结果是可比的, 有利于具有库仑修正的三点求和规则(3PSR)方法所得的结果. 相似文献
8.
9.
本文讨论了J/ψ的强子衰变过程J/ψ→V1+X,X→V2+V3,V2,V3→2P(或3P)(其中Vi代表矢量介子,P代表赝标介子).对于具有不同自旋-宇称JP的中间态X,得到了相应的角分布的螺旋度形式.这些公式对于利用BEPC上得到的J/ψ事例,确定上述过程中间态X的自旋-宇称是有帮助的. 相似文献
10.
11.
A picture for the hadronic structure is discussed based on previous work[1]. The radius contributed from the valence Fock-state wavefunction (i.e., qq component) is calculated in ~ the light-cone framework. We propose a concept of the characteristic length λ to represent the contributions of higher Fock states to hadronic radii phenomenologically and calculate its value. Using an equivalence between the "intrinsic" radii of constituent quarks and the radii coming from higher Fock states we put forward a constraint on the hadronic wavefunctions of mesons. It is found that these wavefunctions lead to consistency between theories and experiments for D and B exclusive decays. We also give the radii for K, D and B mesons. The results show that the radius of K meson is in good agreement with experimental data. 相似文献
12.
R. Barate et al. 《The European Physical Journal C - Particles and Fields》1998,4(3):387-407
A search for doubly-charmed B decays with both charmed mesons reconstructed is performed, using about 3.8 million hadronic
Z decays recorded with the ALEPH detector at LEP. A clear signal is observed in the channels and (where D can be either a D, a D or a D), providing the first direct evidence for doubly-charmed B decays involving no production. Evidence for associated and production in the decays is also presented and some candidates for completely reconstructed decays , and are observed. Furthermore, candidates for the two-body Cabibbo suppressed decays and are also observed. Measurements of the corresponding branching fractions are extracted.
Received: 6 March 1998 / Published online: 23 June 1998 相似文献
13.
《Zeitschrift fur Physik C Particles and Fields》1997,76(3):425-440
Results are presented on the production of excited charm and excited charm-strange mesons in hadronic Z0 decays. The results are obtained from approximately 4.3 million hadronic Z0 decays, collected on or near the Z0 resonance using the OPAL detector at LEP. The D0 1(2420) and D*0 2 (2460) mesons are reconstructed in the D*+π-. final state and their separate production rates in charm fragmentation and in weak decays of b-hadrons are determined. Assuming that the decay widths of these mesons are saturated by the allowed D*π and Dπ final states, the charm hadronization fractions and the inclusive branching ratios of b-hadrons to these neutral P-wave charm mesons are determined to be 相似文献
14.
《Zeitschrift fur Physik C Particles and Fields》1997,73(4):601-612
A sample of 3.6 million hadronic Z decays recorded between 1991 and 1995 with the ALEPH detector at LEP is used to investigate semileptonic decays of B mesons into final states involving orbitally excited charm mesons. Topological vertex criteria are used to search for decays involving narrow D** states as well as wide D** resonances and non-resonant D(*)π final states. The sum of the branching ratios for these processes is measured to be ${? Br}({?erline {? B}}?ghtarrow {? D}? ?l^{-}{?erline v}) + {? Br}({?erline {? B}}?ghtarrow {? D}^{?t}? ?l^{-}{?erline v})?op =(2.26 pm 0.29({? stat}) pm 0.33({? syst}))%,$which accounts for a significant fraction of the deficit between inclusive measurements and the sum of exclusive semileptonic B decay modes. 相似文献
15.
Kwei-Chou Yang 《Czechoslovak Journal of Physics》2003,53(8):707-715
Within the framework of QCD factorization, we discuss various important corrections arising from higher twist distribution amplitudes of mesons in the hadronic B decays. 相似文献
16.
R.A.Briere 《中国物理C(英文版)》2010,34(6):765-773
Several recent CLEO-c results on hadronic decays of charm mesons are reviewed.Topics include measurements of precision branching fractions for exclusive modes,investigations of inclusive rates,and analyses of Dalitz plots.In addition,the quantum correlations of the D pairs produced at the ψ(3770) are exploited to measure phase information that is of current interest for both D and B physics. 相似文献
17.
A. Ali J. G. Körner G. Kramer J. Willrodt 《Zeitschrift fur Physik C Particles and Fields》1979,1(3):269-277
Based on the Kobayashi-Maskawa weak current model we investigate the properties of weak hadronic decays of the anticipated bottom mesons. Our main results concern twobody and quasitwobody decays of bottom mesons into pseudoscalar and vector mesons. 相似文献
18.
We describe a new method for extracting weak, CP-violating &Dmacr;phase information, with no hadronic uncertainties, from an angular analysis of B-->V1V2 decays, where V1 and V2 are vector mesons. The quantity sin (2)(2beta+gamma) can be cleanly obtained from the study of decays such as B(0)(d)(t)-->D*+/-rho(-/+), D(*+/-)a(-/+)(1), D(;) *0K(;) (*0), etc. Similarly, one can use B(0)(s)(t)-->D(*+/-)(s)K*-/+ to extract sin (2)gamma. There are no penguin contributions to these decays. It is possible that sin (2)(2beta+gamma) will be the second function of CP phases, after sin2beta, to be measured at B factories. 相似文献
19.
I.I.Y. Bigi 《Nuclear Physics B》1981,177(3):395-412
We develop a formalism for describing hadronic weak annihilation decays in analogy to the treatment of deep inelastic lepton-nucleon scattering: we write down evolution equations for colour singlet and octet systems inside mesons of increasing mass. Using D decays as input we can predict weak annihilation decay rates of heavier mesons in a semiquantitative fashion despite our ignorance on bound-state dynamics. 相似文献
20.
R. Barate et al. 《The European Physical Journal C - Particles and Fields》2001,20(3):431-443
A search for CP violating effects in the mixing of neutral B mesons is performed using a sample of 4.1 million hadronic Z
decays collected with the ALEPH detector from 1991 to 1995. By studying time-dependent asymmetries in flavour-tagged samples
of semileptonic and fully inclusive b-hadron decays, two measurements of the semileptonic asymmetry are extracted. No evidence for CP violation is observed, and the combined value is obtained.
Received: 26 July 2000 / Published online: 8 June 2001 相似文献