Role of t-channel meson exchanges in S-wave πN and KN scatterings

The low-energy S-wave πN and KN scatterings are studied by using the K-matrix approach within the meson exchange framework.The t-channel meson exchanges,especially ρ and σ exchanges,are found to play a very important role in these two processes.The t-channel ρ exchange determines the isospin structure of the scattering amplitudes,it gives attractive force in the low isospin state but repulsive force in the high isospin state.The t-channel σ exchange gives a very large contribution in these two processes,while it is negligible in meson-meson S-wave scatterings.     

Experimental Study of Resonance f2(1270) in the J/ψ Hadronic Decay

Based on the 2.5 million J/ψ's collected by the BES at BEPC,through the hadronic decay J/ψ→ωf₂(1270),f₂(1270)→π⁺π^－,ω→π⁺π^－π⁰,the properties of the resonance f₂(1270) are studied:its mass,width,and branching ratio.the angular distribution is fitted with maximum likelihood methood,determining its.J^PC=2⁺⁺ and giving in the first time the helicity amplitude ratios of this process as:x=0.99±0.29; y=－0.24±0.17; z₁=0.90±0.57;z₂=0.56±0.22.     

J/ψ Physics at BES

Based on 9.0×10⁶ J/ψ data collected at BES, a systematic physics analysis has been Performed. We confirmed the existence of ξ(2230) in J/ψ→γKK and observed for the first time the non-strange decay modes ξ(2230)→π⁺π^－,π⁰π⁰,and pp. The resonance and polarization parameters of f₀(980) and f₂(1270) were measured. The moment stUdy on J/ψ→γK⁺K^－ revealed that the controversial f_J,(1710) is composed of two states, a 0⁺⁺ and a 2⁺⁺. With the help of PWA method, the spin-Parities for η(1440) and f₀(1500) were obtained, and their main decay modes were found.     

Chiral Lagrangian Treatment of 0^＋＋ Mesons and 0^＋＋ Glueballs

Within the framework of a nonlinear chiral Lagrangian the mass spectra and the decay properties of 0^＋＋ states below 2 GeV are studied. Assuming that f0（980）, a0（980）, K0（1430）, and f0（1500） comprise an SU（3） nonet, we make a detailed prediction about the static properties of the 0^＋＋ mesons. The substructure analysis of these states in terms of two- and four-quark components as well as a glueball component is carried out. We also consider the interaction Lagrangian and provide a preliminary study of the strong and radiative decays of the 0＋＋ mesons. The scalar glueball masses and partial widths are also presented. In view of the fact that few data of 0＋＋ mesons are clearly given in the present PDG （Particle Data Group） list and that the four-quark content of mesons is a hot issue both experimentally and theoretically, the predicted results of the paper may be helpful for upcoming experimental and theoretical studies of these mesons.     

Branching ratio of rare decay B0(Bs)→γνν

The three-body decay B⁰(B_s)→γνν can occur via penguin and box diagrams in the Standard Model (SM). These channels are useful to determine the decay constant f_B (f_Bs) and B (B_s) meson wave function. Using the B meson wave function determined in hadronic B (B_s) decays, we calculate and get the branching ratio of order 10^－9 and 10^－8 for B⁰ and B_s decay, respectively. They agree with previous calculations.     

关于π-π共振态

本文从解析性和么正性出发,对具有共振行为的π-π散射分波振幅的形式作了普遍的讨论。理论中包含了一个标志与Breit-Wigner共振形式偏离的函数F_(l)^I)(v),当F_(l)^I)(v)=1时,振幅恰好具有Breit-Wigner共振形式。具体计算表明,这个函数与1有一定的偏离。利用ND^-1方法、交叉对称性、ρ与f⁰的Bootstrap近似,将所得到的振幅与-90的共振解。计算中考虑了非弹性过程和负半轴色散积分的贡献。计算结果得到,对于J=1,I=1态,v_R=6.4,Г₁=0.12;对于J=2,I=0态,v_(R2)=20,Г₂=0.016。这相当于m_ρ=762MeV,m_f⁰=1283MeV,ρ的半宽度约为45MeV。它们与目前的实验数据是很好符合的。     

Multi-channel Coupling in the Hadronic Decay Process J/ψ→ωπ+π－

The coupling problem of the three different intermediate processes J/ψ→ωf₂(1270),f₂→π⁺π^－ and J/ψ→b₁^±(1235)π⁺,b₁^±→ωπ^± included in the hadronic decay process J/ψ→ωπ⁺π^－ is discussed.The consideration of the coupling effect is very important for measuring the parameters of the resonances f₂ and b₁^± and the helicity amplitude ratios of these reactions precisely.     

Ds（0^±） Meson Spectroscopy in Gaussian Sum Rules

Masses of the Ds（0^±） mesons are investigated from a view-point of ordinary light-heavy system in the framework of the Gaussian sum rules, which are worked out by means of the Laplacian transformation to the usual Borel sum rules. Using the standard input of QCD non-perturbative parameters, the corresponding mass spectra and couplings of the currents to the Ds（0^±） mesons are obtained. Our results are mDs（0-） = 1.968±0.016±0.003 GeV and mDs（0＋） = 2.320 ±0.014 ± 0.003 GeV, which are in good accordance with the experimental data, 1.969 GeV and 2.317 GeV.     

Rare decays B0s,d→l+l－ in a top quark two-Higgs-doublet model

In the framework of T2HDM, we calculated the new physics contributions involving neutral Higgs bosons to the branching ratios of B⁰_s,d→l⁺l^－ (l=e, μ) decays. Comparing the theoretical predictions with the experimental upper-limits, we found that (a) The data of Br(B⁰_d→l⁺l^－) give the upper bound on tanβ: tanβ≤22, while Br(B⁰_s→l⁺l^－) give tanβ≤12 for fixed δ=0°, m_H+=350 GeV, m_H0=160 GeV, m_h0=115 GeV and m_A0=120 GeV; (b) A light neutral Higgs boson mass m_h0 (m_A0) less than 50 GeV (120 GeV) is excluded by the data of branching ratios for B⁰_s,d→l⁺l^－(l=μ) decays with tanβ=10; (c) The bounds on m_h0 and tanβ, or m_A0 and tanβ are strongly correlated: a smaller (larger) tanβ means a lighter (heavier) neutral Higgs boson.

     

Determining the Spin-Parity of the Boson Resonance X in the Process J/ψ→X+f0 (980) by Using the Generalized Moment Analysis Method

The processes J/ψ→X+f₀ (980), X→K⁺ K^－,f₀ (980)→π⁺+π^－ are discussed using the generalized moment analysis method. It is suggested that in terms of the obtained moment expressions the spin-parity of the boson resonance X can be determined by further measurements.     

The Spin Effect of Antiproton-Nucleus Inelastic Collison

If the antiproton optical potential is inclusive of the spin orbit interaction term,the A(p,p)A* inelastic scattering not only can excited the normal parity states,but also can excited the abnormal parity states.There are also induced the polarization P_f(θ) at the inelastic scattering.In the framework of DWIA,we derived the inelastic scattering cross section (dσ/dΩ)_f,i,and polarization P_f(θ),and calculated the (dσ/dΩ)_f,i, and P_f(θ) for ¹²C(p,p)¹²C* with 2⁺,3^－ and 1⁺ states at antiproton energies of 46.8 and 179.7MeV.They fited experiment data quite well.Due to the abnormal partity states in the inelastic process have been measured,the spin orbit term can not be neglect.     

Separation of S-wave pseudoscalar and pseudovector amplitudes in π−P↑ → π+π−n reaction on polarized target

A new analysis of S-wave production amplitudes for the reaction π^?p↑ → π⁺π^?n on a transversely polarized target is performed. It is based on the results obtained by the CERN-Cracow-Munich collaboration in the ππ energy range from 600 MeV to 1600 MeV at 17.2 GeV/c π^? momentum. Energy-independent separation of the S-wave pseudoscalar amplitude (π exchange) from the pseudovector amplitude (a ₁ exchange) is carried out using assumptions much weaker than those in all previous analyses. We show that, especially around 1000 MeV and around 1500 MeV, the a₁ exchange amplitude cannot be neglected. The scalarisoscalar ππ phase shifts are calculated using fairly weak assumptions. Below the KK? threshold we find two solutions for the π — π phase shifts, for which the phases increase slower with the effective π — π mass than the P-wave phases. Both solutions are consistent with a broad f ₀(500) but only one is similar to the well-known “down” solution. We find also the third solution (with a somewhat puzzling behavior of inelasticity) which exhibits a narrow f ₀(750) claimed by Svec. All the solutions undergo a rapid change at the KK? threshold. Above 1420 MeV the phase shifts increase with energy faster than those obtained without the polarized-target data. This phase behavior as well as an increase of the modulus of the a₁-exchange amplitude can be due to the presence of the f ₀(1500).     

The reaction Pomeron-Pomeron →π + π − and an unusual production mechanism for thef 2 (1270)

Data are presented on Pomeron-Pomeron interactions which produce a centralπ ⁺ π ^? system in proton-proton collisions at \(\sqrt s = 62 GeV\) at the CERN Intersecting Storage Rings. This process may favor the production of gluonic bound states. A partial-wave analysis of theπ ⁺ π ^? system shows evidence for the production of the statesf ₀(975),f ₀(1400), andf ₂(1270). The fitted mass for thef ₂(1270) is about 50 MeV below the world average. In addition, the production mechanism for thef ₂(1270) is uniquely different from that for the other final states in that there is a correlation between the outgoing protons. this is consistent with a picture of two-gluon exchange with thef ₂(1270) produced by gluon fusion, and could indicate that thef ₂(1270) has a glueball component.     

The N*(1710) contribution to the Θ+ production cross sections in p-p collisions

In this paper we derive the Θ production cross section in high energy proton-proton collisions in the relativistic framework through using effective hadronic couplings. Both the nucleon and N^*(1710) propagations are taken into account in the intermediate states. The one π and one ρ exchange mechanisms are considered and the commonly accepted coupling constants and form factors are used in the calculation. We find that ρ exchange is dominant in these processes and the N^*(1710) propagation in the intermediate state is important,which increases the Θ production cross section by a factor of a few tens at center of mass energy 4GeV.     

QUARK MASS RENORMALIZATION IN LATTICE GAUGE THEORY (Ⅱ) BARYON MASS CALCULATION

Using the renormalized quark mass m(g) obtained by fixing the ρ meson mass, we calculate the masses of the baryon states as a function of 1/g² in lattice gauge theory with fermions by variational method. The results are in agreement with experimental values in the range of 1/g² between 0.1 to 0.9.     

Structure Analysis of the l/η(1440)

By an amplitudes analysis of the KKπ system in the J/ψ radiative decay to the K⁺K^－π^O and the K⁰_SK^±π⁺ final states, we find that there is one 0^－+ resonance (M=1467±3MeV,Γ=89±6MeV) and two 1⁺⁺ resonances (M=1435±3MeV,Γ=59±5MeV and M=1497±2MeV,Γ=44±7MeV), Which are consistent with the η(1440), the f₁(1420), and the f₁(1510).     

定义在分形集上函数的H-导数

 分形的生成含有降维与升维两种形式,采用适当的方式总可以对分形集加以定向化,分形的内禀测度是Hausdorff测度。因此,定义在分形集上的函数可以看作是在Hausdorff测度下定义在区间[0, h]。在函数图像也是分形的前提下,依函数的Hausdorff测度的定义,给出了定义在分形集上的函数f(p)关于Hausdorff测度p的导数以及一些性质。     

Measurement of neutral-meson masses in meson-nucleus interactions at a momentum of 7 GeV/c at the Hyperon-M setup

The π ⁰, η, K ⁰, ω, and f ₂(1270) masses were measured at the HYPERON-Msetup in meson-nucleus interactions at a momentum of 7 GeV/c by using six nuclear targets: Be, C, Al, Cu, Sn, and Pb. The experiment in question proved to be insensitive to the expected effects of a modification to the omega-meson mass in nuclear matter. As for the f ₂(1270) meson, its mass and width values averaged over all experimental data, $m_{f_2 }$ = 1275.8 ± 1.0(stat.) ± 0.4(syst.) MeV/c ² and $\Gamma _{f_2 }$ = 190.3 ± 1.9(stat.) ± 1.8(syst.) MeV/c ², agree well with the world-average values. At the same time, our experimental data do not rule out the possible effect of an in-medium modification to the f ₂(1270)-meson mass for heavy nuclei at a level better than 0.4%.     

Inclusive production of non-strange resonances inK − p interactions at 32 GeV/c

New data on the inclusive production of the non-strange resonances ?⁰(770), ω(783), ?(1020) andf(1270) inK ^? p interactions at 32 GeV/c are presented. The inclusive production cross sections are equal to (4.32±0.72) mb, (3.7±1.4) mb, (0.65±0.10) mb and (0.91±0.35) mb respectively. Estimates of the topological cross sections are also obtained. The invariant and non-invariantx-distributions for the vector mesons ?⁰ and ? indicate the prevalence of forward resonance production in the c.m. system. For the tensorf-meson the rapidity andx-distributions are presented. Thet′-distributions for ?⁰, ?, andf have exponential slopes of 0.6±0.1 GeV^?2, 1.2±0.2 GeV^?2, and 0.8±0.5 GeV^?2 respectively. The exponential slope ofp _T ² -distribution of thef-meson is equal to (2.3±0.5) GeV^?2.