Search for ψ(4S) → ηJ/ψ in B~±→ ηJ/ψK~± and e~+e~-→ ηJ/ψ processes

We search for the ψ(4S) state in the B~±→ηJ/ψK~± and e~+e~-→ηJ/ψ processes based on the Belle measurements with the assumed mass M =(4230±8) MeV/c~2 and width Γ =(38±12) MeV. No significant signal is observed in the ηJ/ψ mass spectra. The 90% confidence level upper limit on the product branching fraction B(B~±→ψ(4S)K~±)B(ψ(4S)→ηJ/ψ) 6.8×10~(-6) is obtained in the B~±→ηJ/ψK~± decays. By assuming the partial width of ψ(4S)→e~+e~-to be 0.63 ke V, a branching fraction limitB(ψ(4S)→ηJ/ψ) 1.3% is obtained at the 90%confidence level in e~+e~-→ηJ/ψ, which is consistent with the theoretical prediction.     

ι-E疑难和推广的矩分析

本文引进过程e~+e~-→J/ψ→γB,B→P_1P_2P_3的矩的光子角分布来讨论■E疑难,得到了判断J/ψ→γKK_π过程中产生的共振峰是否包含E(1~(++))分量的一个有效判据.     

J/φ强子衰变过程的角分布螺旋度形式

本文给出了e~+e~-→J/φ→V+X,V→P_1P_2和e~+e~-→J/φ→V+X,X→P_4P_5过程的角分布螺旋度形式.为e~+e~-实验数据分析提供了理论公式.     

过程e~+e~-→J/ψ→γB,B→P_1P_2的角分布和玻色子B的自旋分析

本文给出了过程e~+e~-→J/ψ→γB,B→P_1P_2的螺旋性形式(HF)~[1]和等效相互作用形式(EIF)~[2]之间的关系.在B的不同自旋(J=2,4)下赝标介子的角分布显示,为了确定B的自旋,存在敏感区域和不敏感区域.令人遗憾的是,θ/f_2(1720)和ξ(2230)的数据正好掉入不敏感区域.     

J/φ强子衰变过程的矩分析

本文给出了过程e~++e~-→J/ψ→V+X,V→P_1P_2或P_1P_2P_3和X→PP的角分布螺旋度形式,并在此基础上进行了矩分析,得到了若干关系式,有助于确定玻色共振态X的自旋J_x以及过程J/ψ→V+X的螺旋度振幅之比.     

Study of the η'→Ve~+e~- decay with hidden local symmetry model

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.     

Study of the η’→Ve~+e~- decay with hidden local symmetry model

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.     

Nucleon resonances in πN→η'N and J/ψ→pη'

We are aiming to study the J/Ψ→Pη' decay in an isobar model and the effective Lagrangian approach on the basis of the coupling constants extracted from the πN→η'N reaction.After a careful exploration of the contributions of the S_(11)(1535),P_(11)(1710),P_(13)(1900),S_(11)(2090) and P_(11)(2100) resonances,we conclude that either a subthreshold resonance or a broad P-wave state in the near threshold range seems to be indispensable to describe the present data of the πN→η'N.Furthermore,at least one broad resonance above η'N threshold is preferred.With this detailed analysis,we give the invariant mass spectrum and Dalitz plot of the J/Ψ→Pη' decay for the purpose of assisting the future detailed partial wave analysis.It is found that the J/Ψ→Pη' data are useful for disentangling the above or below threshold resonant contribution,though it still further needs the differential cross section data ofπN→η'N to realize some of the resonant and non-resonant contribution.     

关于η_c′粒子及其电磁衰变

本文在势模型的框架内,估算了η′_c粒子的质量、宽度及几种主要电磁衰变道的分支比。指出禁戒型磁跃迁η′_c→J/φγ的相对论修正结果比简单的非相对论估算有可能大一个量级。讨论了北京正负电子对撞机(BEPC)对级联电磁辐射过程φ′(3686)→γη′_c→γγ~1P_1,γγJ/φ,3γ进行测量的可能性。     

成像光学系统总性能的单一评价指标

本文在论证了用空间信息量表示成像光学系统总体性能的基础上,提出了信息量的计算公式F=K(J~2/λ~2)·(S~2/S_0~2)或F=K(J~2/λ~2)·(M~2/M_0~2)或F=K(J~2/λ~2)·(P~2/P_0~2),阐述了它的物理意义,并给出了计算实例.     

Event generators for η/η' decays at BESⅢ

The light unflavoured meson η/η' decays are valuable for testing non-perturbative quantum chromodynamics and exploring new physics beyond the Standard Model. This paper describes a series of event generators, including η/η'→γl~+l~-, η/η'→γπ~+π~-, η'→ωe~+e~-, η→π~+π~-π~0, η/η'→π~0π~0π~0, η'→ηππ andη'→π~+π~-π~+π~-/π~+π~-π~0π~0, which have been developed for investigating η/ηdecay dynamics. For most of these generators, their usability has been validated in BESIII analyses for determining the detection efficiency, and background studies. The consistency between data and Monte Carlo shows that these generators work well in the BESⅢ simulation, and will also be useful for ongoing BESⅢ analyses and other experiments for studying η/η' physics.     

Observation of e~+e~-→D_s~+■~((*)0)K~- and study of the P-wave D_s mesons

Studies of e~+e~→D_s~+■~((*)0)K~-and the P-wave charmed-strange mesons are performed based on an e~+e~-collision data sample corresponding to an integrated luminosity of 567 pb~(-1) collected with the BESIII detector at s~(1/2)=4.600 GeV. The processes of e~+e~-→D_s~+■~(*0)K~- and D_s~+■~0K~- are observed for the first time and are found to be dominated by the modes D_s~+D_(s1)(2536)~-and D_s~+D_(s2)~*(2573)~-, respectively. The Born cross sections are measured to be σ~B(e~+e~-→D_s~+■~(*0)K~-) =(10.1±2.3±0.8) pb and σ~B(e~+e~-→D_s~+■~0K~-) =(19.4±2.3± 1.6) pb, and the products of Born cross section and the decay branching fraction are measured to be σ~B(e~+e~-→D_s~+D_(s1)(2536)~-+c.c.)·B(D_(s1)(2536)~-→■~(*0)K~-)=(7.5±1.8±0.7) pb and σ~B(e~+e~-→D_s~+D_(s2)~*(2573)~-+ c.c.)·B(D_(s2)~*(2573)~-→■~0 K~-)=(19.7 ± 2.9 ±2.0) pb. For the D_(s1)(2536)~-and D_(s2)~*(2573)~-mesons, the masses and widths are measured to be M(D_(s1)(2536)~-)=(2537.7±0.5 ±3.1) MeV/c2, Γ(D_(s1)(2536)~-) =(1.7 ±1.2 ±0.6)MeV, and M(D_(s2)~*(2573)~-)=(2570.7±2.0 ±1.7) MeV/c~2, Γ(D_(s2)~*(2573)~-)=(17.2 ±3.6 ±1.1) MeV. The spin-parity of the D_(s2)~*(2573)~-meson is determined to be J~p= 2~+. In addition, the processes e~+e~-→D_s~+■~((*)0)K~-are searched for using the data samples taken at four(two) center-of-mass energies between 4.416(4.527) and 4.575 GeV, and upper limits at the 90% confidence level on the cross sections are determined.     

Branching ratio and CP asymmetry of Bs→K0(1430)η(') decays in the PQCD approach

In the two-quark model supposition for K0*(1430), which can be viewed as either the first excited state (ScenarioⅠ) or the lowest lying state (Scenario Ⅱ), the branching ratios and the direct CP-violating asymmetries for decays s0 → K0*0(1430)η (’) are studied by employing the perturbative QCD factorization approach. We find the following results: (a) The CP averaged branching ratios ofs0 → K0*0 (1430)η ands0→ K0*0(1430)η’ are small and both in the order of 10-7 . If one views K0* (1430) as the lowest lying state, B(s0→K0*0(1430)η) ≈ 3.9×10-7 and B(s0→K0*0(1430)η’) ≈ 7.8×10-7.(b) While the direct CP-violating asymmetries of these two decays are not small: if we still take the parameters of K0* (1430) in scenario , ACPdir(s0→K0*0(1430)η) ≈ 56.2% and ACPdir(s0→ K0*0(1430)η’) ≈ 42.4%. (c) The annihilation contributions will play an important role in accounting for future data, because both the branching ratios and the direct CP asymmetries of these two decays are sensitive to the annihilation type contributions.     

B→η′K(K),ηK(K)衰变过程的分析

对B→η′K(K^*),ηK(K^*)过程的最新实验结果及各种可能的理论解释做了系统分析,并对某些衰变机制的实验检验做了简要讨论.     

B→Kη~(,) decays in the SM with fourth generation fermions

By employing the perturbative QCD(pQCD) factorization approach, we calculate the new physics contributions to the four B→Kη()decays in the Standard Model(SM) with a fourth generation of fermions(SM4),induced by the loop diagrams involving t quark. Within the considered parameter space of the SM4 we find that:(a) the next-to-leading order(NLO) pQCD predictions for the branching ratios and CP-violating asymmetries in both the SM and SM4 generally agree with the data within one standard deviation;(b) for Br(B→Kη), the inclusion of the fourth generation contributions can improve the agreement between the theoretical predictions and the data effectively;(c) however, for Br(B → Kη) the decrease due to t loops is disfavored by the data; and,(d) the new physics corrections to the CP-violating asymmetries of the considered decays are only about 10%.     

Semileptonic Decays B＊→ηclυl with QCD Sum Rules

In this article, we calculate the B＊→ηc form-factors with the three-point QCD sum rules, then study the semileptonic decays B＊→ηclυl. The tiny decay widths may be observed experimentally in the future at the LHCb, while the B＊→ηc form-factors can be taken as basic input parameters in other phenomenologieal analysis.     

Pair Production of the Doubly Charged Leptons Associated with a Gauge Boson γ or Z in e~+e~-and γγ Collisions at Future Linear Colliders

In this paper,we investigate the production of a pair of doubly charged leptons associated with a gauge boson V(γ or Z) at future linear colliders via e~+e~-and γγ collisions.The numerical results show that the possible signals of the doubly charged leptons may be detected via the processes e~+e~→VX~(++)X~(--)and γγ→VX~(++)X~(--)at future ILC or CLIC experiments.     

B→Kη′中双胶子聚合机制的进一步研究

双胶子聚合机制可能解释B→Kη′反常大的分支比.然而由于我们对η′犂犂有效顶点知之甚少,微扰QCD的理论计算存在很大的不确定性.本文尝试了几种不同的η′犂犂形状因子,并将数值结果和实验相比较.我们发现,虽然我们对η′犂犂形状因子了解得很少,但是如果B→Kη′衰变中双胶子聚合机制确实很重要的话,B→K^*η′的分支比将为10^－5量级,这可以被将来的实验检验.     

高能正负电子对的湮没与超窄共振粒子的作用

本文给出了R=σ(e~ e~-→强子)/σ(e~ e~-→μ~ μ~-)随能量上涨的一个解释。研究了新发现ψ粒子所具有作用的性质,指出其强度f~2/4π～10~(-5)—10~(-6)。求得峰值截面σ=12π/m_ψ~2Γ(ψ→e~ e~-)/Γ~(tot),指出ψ的真正宽度比目前实验上限小一个量级。讨论了ψ的视宽度△E、平均峰值截面σ_0和质量M_ψ的关系,得到了σ_0△EM_ψ~4=常数,和实验相符。     

B→K_0~*(1430)η~(') decays in the pQCD approach

Based on the assumption of two-quark structure of the scalar meson K*0(1430),we calculate the CP-averaged branching ratios for B→K0*(1430)η(') decays in the framework of the perturbative QCD(pQCD) approach here.We perform the evaluations in two scenarios for the scalar meson spectrum.We find that:(a) the pQCD predictions for Br(B→K*0(1430)η(')) which are about 10-5-10-6,basically agree with the data within large theoretical uncertainty;(b) the agreement between the pQCD predictions and the data in Scenario ...