共查询到20条相似文献,搜索用时 500 毫秒
1.
2.
We analyze the φ meson production in e+e-→ωπ0 as a probe for studying the isospin violation mechanisms.By clarifying the dynamic sources causing the isospin violation,we succeed in quantifying those mechanisms with the help of the recent KLOE data.Hence,the φ→ωπ0 branching ratio is extracted.We find that apart from the electromagnetic(EM)transitions,the strong transition via intermediate kaon loops plays an important role in understanding the cross section and its lineshape. 相似文献
3.
M.N.Achasov K.I.Beloborodov A.V.Berdyugin A.A.Botov V.B.Golubev T.V.Dimova V.P.Druzhinin L.V.Kardapoltsev A.G.Kharlamov D.P.Kovrizhin I.A.Koop A.A.Korol S.V.Koshuba A.E.Obrazovsky E.V.Pakhtusova D.A.Shtol S.I.Serednyakov Z.K.Silagadze A.N.Skrinsky Yu.A.Tikhonov Yu.M.Shatunov A.V.Vasil'ev 《中国物理C(英文版)》2010,34(6)
In an experiment with the Spherical Neutral Detector at VEPP-2M collider the cross section of the process e+e-→π+π-π0π0 was measured. At energies √s < 920 MeV this cross section was measured for the first time. The energy dependence of the cross section is well discribed by the vector dominance
model with contributions from ρ, ρ' ρ", mesons. The decay probability ρ→π+π-π0π0was found to be Bρ = (1.60±0.74±0.18)×10-5. The upper limit for the decay ω→π+π-π0π0 was improved by two orders of magnitude compared to the previous measurements and is Bω < 2 × 10-4 at 90% confidence level. 相似文献
4.
The cross sections of e+e-→π+π-hc at center-of-mass energies from 3.90 to 4.42 GeV were measured by the BES and the CLEO-c experiments. Resonant structures are evident in the e+e-→π+π-hc line shape. The fit to the line shape results in a narrow structure at a mass of(4216±18) MeV/c2and a width of(39±32) MeV, and a possible wide structure of mass(4293±9) MeV/c2and width(222±67) MeV. Here, the errors are combined statistical and systematic errors. This may indicate that the Y(4260) state observed in e+e-→π+π-J/ψ has a fine structure in it. 相似文献
5.
The dominant decay modes of charged top-pions (π±t ) are tb or ~b. We consider the single production ofcharged top-pions in association with a top quark via e+ e- annihilation and calculate the production cross section of theprocesses e+ e- → t-bπ+ (tb-π-) at the leading order. We find that it can reach 1.2 fb with reasonable parameter values.The charged top-pions may be detected via the channel tbπ± in the future high energy e+ e- colliders. 相似文献
6.
《中国物理C(英文版)》2014,(4):1-4
Abstract: The cross sections of e+e-→π+π-hc at center-of-mass energies from 3.90 to 4.42 GeV were measured by the BESIII and the CLEO-c experiments. Resonant structures are evident in the e+e-→π+π-hc line shape. The fit to the line shape results in a narrow structure at a mass of (4216±18) MeV/c2 and a width of (39±2) MeV, and a possible wide structure of mass (4293±9) MeV/c2 and width (222=k67) MeV. Here, the errors are combined statistical and systematic errors. This may indicate that the Y(4260) state observed in e+e-→π+π-J/ψ has a fine structure in it. 相似文献
7.
利用色散关系研究了弱电流不守恒情况下的π→π~0 e v衰变过程。在对π—π散射相移作了一些假定后,证明了π、π中间态的贡献很小。在N、N中间态项中出现的N、N湮灭矩阵元用Chew-Ball理论及湮灭实验估计,同时出现的核子弱作用形状因子又用色散关系计算,证明了N、N中间态对它的贡献很小,计算了π、π中间态对它的贡献。根据现有N、N湮灭实验估计,π→π~0 e v过程的衰变几率<6×10~(-4)秒~(-1)。 相似文献
8.
9.
Federico Nguyen 《中国物理C(英文版)》2010,34(6):795-800
Studies of γγ interactions are performed with the KLOE detector,without tagging of the outgoing e+e-.The data sample is from an integrated luminosity of 240 pb-1.It was collected at the φ-factory DAΦNE with e+e-beams colliding at s~(1/2) 1 GeV,below the φ resonance peak.We present preliminary results concerning the observation of the γγ→η process and the evidence for γγ→π0π0 production at low π0π0 invariant masses. 相似文献
10.
通过构造适当的关联函数,计算B→π跃迁形状因子fB+π(q2),fBπ(q2)和标量形状因子f0(q2),从而就能研究轻子质量对B0→π-+ν(l=e,μ,τ)衰变过程的影响.首次分别计算B0→π-e+νe,B0→π-μ+νμ,B0→π-τ+ντ衰变过程的分支比,并发现轻子质量me,mμ可以忽略,但重轻子质量mτ不能忽略,它对分支比计算有一定的贡献.把计算结果与最近的实验数据进行比较,发现理论结果与实验数据基本符合. 相似文献
11.
In the framework of T2HDM,we calculated the new physics contributions involving neutral Higgs bosons to the branching ratios of Bs0,d→e+e-(= e,μ) decays.Comparing the theoretical predictions with the experimental upper-limits,we found that(a) The data of Br(B0d →e+e-) give the upper bound on tanβ:tanβ 22,while Br(Bs0 →e+e-) give tanβ 12 for fixed δ = 0°,mH+= 350 GeV,mH0 = 160 GeV,mh0 = 115 GeV and mA0 = 120 GeV;(b) A light neutral Higgs boson mass mh0(mA0) less than 50 GeV(120 GeV) is excluded by the data o... 相似文献
12.
《中国物理C(英文版)》2010,(6)
In an experiment with the Spherical Neutral Detector at VEPP-2M collider the cross section of the process e+e-→π+π-π0π0 was measured.At energies s~(1/2)920 MeV this cross section was measured for the first time.The energy dependence of the cross section is well discribed by the vector dominance model with contributions from ρ,ρ,ρ mesons.The decay probability ρ→π+π-π0π0 was found to be Bρ =(1.60±0.74±0.18)×10-5.The upper limit for the decay ω→π+π-π0π0 was improved by two orders of magnitude compared to the previous measurements and is Bω 2×10-4 at 90% confidence level. 相似文献
13.
《中国物理 C》2002,26(11):1093-1102
利用北京谱仪(BES)在北京正负电子对撞机(BEPC)e+e-质心系能量为4.03GeV处采集的积分亮度为22.3pb-1的数据,从D介子的5个非轻子衰变模式中共选出2471±218组tagD+X(X可能是γ或π0或π±)和7629±251组tagD0X介子样本. 在这些样本中没有找到D+→φe+υ,φK-π+e+υ,和D0→φK-e+υ,φK-μ+υ的衰变事例,测定在90髎置信度下分支比的上限分别为B(D+→φe+υ)<1.38髎,B(D+→φK-π+e+υ)<2.01髎,B(D0→φK-e+υ)<0.53髎,和B(D0→φK-μ+υ)<0.53髎. 相似文献
14.
Within the hidden local symmetry framework, the Dalitz decay η→Ve+e-is studied with the vector meson dominance model. It is found that the partial width Γ(η→ωe+e-)≈40 e V and branching ratio B(η→ωe+e-)≈2×10-4, and Γ(η→ρe+e-)≈10Γ(η→ωe+e-) and B(η→ρe+e-)≈10B(η→ωe+e-). The maximum position of the dilepton distribution is m e+e-≈1.33 Me V. These decays are measurable with the advent of high statistic ηexperiments. 相似文献
15.
利用北京谱仪 (BES -Ⅰ )在北京正负电子对撞机 (BEPC)e+ e-质心系能量为 4 .0 3GeV处采集的积分亮度为 2 2 .3pb-1的数据 ,研究了D0 →K0sπ+ π-,D0 →K0sK+ K-的衰变及其末态的共振结构 .实验测得D0 →K0sπ+ π-过程的分支比为 (5 .32± 0 .5 3± 0 .4 0 ) % ;D0 →K -π+ ,D0 →K0 ρ0 和D0 →K0s(π+ π-)non resonance过程的分支比分别为 (6 .0 5± 0 .32± 0 .4 9) % ,(1.17± 0 .17± 0 .13) %和 (1.35± 0 .2 2± 0 .17) % ;测得D0 →K0sK+ K-,D0 →K0 和D0 → K0 (K+ K-) non 的分支比分别为 (1.0 4± 0 .2 4± 0 .16 ) % ,(1.12± 0 .34± 0 .15 ) %和 (0 .2 7± 0 .13±0 .0 3) % . 相似文献
16.
Within the hidden local symmetry framework, the Dalitz decay η→Ve+e-is studied with the vector meson dominance model. It is found that the partial width Γ(η→ωe+e-)≈40 e V and branching ratio B(η→ωe+e-)≈2×10-4, and Γ(η→ρe+e-)≈10Γ(η→ωe+e-) and B(η→ρe+e-)≈10B(η→ωe+e-). The maximum position of the dilepton distribution is m e+e-≈1.33 Me V. These decays are measurable with the advent of high statistic ηexperiments. 相似文献
17.
18.
通过构造适当的关联函数,计算B→π跃迁形状因子f+Bπ(q2),~fBπ(q2)和标量形状因子f0(q2),从而就能研究轻子质量对B0→π-l+~vl(l=e,μ,τ)衰变过程的影响.首次分别计算B0→π-e+~ve,B0→π-μ+~vμ,B0→π-τ+~vτ衰变过程的分支比,并发现轻子质量me,mμ可以忽略,但重轻子质量mτ不能忽略,它对分支比计算有一定的贡献.把计算结果与最近的实验数据进行比较,发现理论结果与实验数据基本符合. 相似文献
19.
采用中子n-反中子n与中性介子π0强相互作用的Lorentz不变耦合模型,对n-n重正化链图传播子作了有关物理分析及其严格解析计算,获得精确理论计算结果. 进而将此结果用于n+n→2π0反应的物理过程分析及其截面的计算研究中,并精确计算出n-n重正化链图传播下n+n→2π0反应微分截面. 还将此计算结果与n-n树图和重正化单圈链图传播下n+n→2π0反应微分截面作了对比分析,获得了有关辐射修正的重要信息. 此结果对于深
关键词:
Lorentz不变耦合模型
重正化链图传播子
微分截面
辐射修正 相似文献
20.
WANG Wen-Feng 《中国物理C(英文版)》2010,34(6):692-697
We present a precise BABAR measurement on the cross section of the process e+e-→π+π-(γ) from threshold to an energy of 3 GeV with the initial state radiation(ISR) technique,using 232 fb-1 of data collected with the BABAR detector at e+e-center-of-mass energies near 10.58 GeV.The ISR luminosity is determined from a study of the leptonic process e+e-→μ+μ-γ(γ).The leading-order hadronic contribution to the muon magnetic anomaly calculated using the ππ cross section measured from threshold to 1.8 GeV is(514.1±2.2(stat)±3.1(syst))×10-10. 相似文献