pp final state interaction in J/ψ →γpp

The phenomenon of the near ppˉ-threshold enhancement observed in the J/ψ→γ pp decay is studied by using the enhancement factor method with a simpler one-pion-exchange potential between p and p. The Jost function caused by the mentioned potential is perturbatively calculated in the zero-th order approximation, and the corresponding enhancement factor is obtained. It is found that such a final state interaction offers an important contribution to the decay width near the ppˉ-threshold, although it is not large enough. To explain the decay data, a phenomenological factor G(p) with the form of 285500/(m 2 π + p 2 ) should be introduced. A further calculation including the p-dependent bare T -matrix, a more realistic N ˉ N potential and the contribution from the higher-order wave functions would provide a better understanding of the decay data and even the existence of the baryonium ppˉ. The near ppˉ-threshold behavior of the decay width in the J/ψ→π 0 pp process is also discussed.     

过程pp/pp→hbb+X的超对称QCD残留效应

当一个轻黑格斯玻色子除外的所有超对称粒子的质量谱都超重而不可能在目前的强子对撞机上产生时, 就需要寻求其他的途径来探索超对称信号的存在证据. 黑格斯玻色子产生相关过程的超对称粒子虚修正效应提供了可能性. 研究了强子对撞机上轻黑格斯玻色子和一个bottom夸克对末态产生过程的超对称QCD修正效应. 结果发现, 如果过程相关的超对称粒子胶微子和标夸克太重(大于TeV标度)而不能直接产生, 但是它们对此过程依然有显著的虚修正效应. 尤其是对于大的tanβ值, 这种残留效应可以为截面带来超过40%的修正.显然这样大的修正结果在将来的强子对撞机上是可观的.     

Complementary studies on N＊ from e＋e-, pp and pp collisions

Complementary to the conventional experimental studies on N＊ from πN and γ（＊）N reactions, the e＋e-, pp and pp collisions can give novel insights into these N＊ resonances. While the e＋e- collisions through production and decay of vector charmonium ψ provide a nice isospin filter for a simultaneously study of N＊, △＊, ∧＊, ∑＊ and 2＊, the pp collisions should be the best place for producing those △＊＋＋ with large coupling to p＋p though pp →nA＊＋＋ reaction, and the pp collisions should be the best place for looking for those N＊ with large coupling to σN.     

Partial wave analysis ofJ/ψ）→ppπ0 and measurement of J/ψ→ppη,ppη＇

Based on 58 million J/ψ data collected with the BESII detector at the BEPC, Partial Wave Analysis（PWA） is performed on J/ψ→ppπ0. The new excited baryon N（2065） is confirmed. Clear signals for other N＊ states are observed and the corresponding masses, widths and spin-parity are also measured. Processes such as J/ψ→ppη,ppη＇
are also studied and the branching ratios are measured.     

Λ∧ production in pp collis

We describe the production of Λ Λ in pp collisions using a constituent quark model which has been successfully applied to the N N system.     

Near-threshold η production in pp collisions

We study near-threshold η meson production in pp collisions within an effective Lagrangian approach combined with the isobar model, by allowing for the various intermediate nucleon resonances due to the π, η, and ρ-meson exchanges. It is shown that the ρ-meson exchange is the dominant excitation mechanism for these resonances,and the contribution from the N*(1720) is dominant. The total cross section data can be reasonably reproduced,and the anisotropic angular distributions of the emitted η meson are consistent with experimental measurements.Besides, the invariant mass spectra of pp and pη explain the data well at excess energy of 15 Me V, and are basically consistent with the data at excess energy of 40 Me V. However, our model calculations cannot reasonably account for the two-peak structure in the pη distribution at excess energies of 57 and 72 Me V, which suggests that a more complicated mechanism is needed at higher energy region.     

N~*(1535) contribution in pp→ ppη' and pn→dφ

In an effective Lagrangian model we find that the N*(1535) resonance contribution might be important to the interpretation of the present data of the pp→ ppη' and pn→dφ reactions. The strong coupling strength of N~* (1535) to η' and φ are indicated, and the possible implication to the intrinsic component of N~*(1535) is explored. These results may provide hints to the real origin of the OZI rule violation. It is stressed that further measurements could be performed at the Cooling Storage Ring (CSR) at Lanzhou of China.     

pp→ΛΛ过程的胶子交换势与pp→ΛΛ过程的反应截面

本文给出了夸克-反夸克对 湮没和夸克-反夸克对 产生过程的单胶子和双胶子交换势准至P²/m²级近似的形式,据此推出了pp→ΛΛ过程的等效位势.应用这个位势在平面波玻恩近似(PWBA)下计算pp→ΛΛ反应的微分截面和总截面,得到了与实验符合得较好的结果.     

Chiral dynamics and the reactions pp↦dK+ and pp↦dπ+η

We perform a study of the final-state interactions of the K ⁺ and the d systems in the reactions pp↦dK ⁺ and pp↦dπ⁺η. Since the two-meson system couples strongly to the a ₀(980) resonance, these reactions are expected to be an additional source of information about the controversial scalar sector. We also show that these reactions present peculiar features which can shed additional light on the much debated meson-baryon scalar sector with strangeness -1. We deduce the general structure of the amplitudes close to the dK ⁺ threshold, allowing for primary K ⁺ as well as π⁺η production with the two mesons in relative S- or P-wave. The interactions of the mesons are accounted for by using chiral unitary techniques, which generate dynamically the a ₀(980) resonance, and the d interaction is also taken into account. General formulae are derived that allow to incorporate the final-state interactions in these systems for any model of the production mechanism. We illustrate this approach by considering two specific production mechanisms based on three flavor meson-baryon chiral perturbation theory. It is demonstrated that in this scenario the d interactions are very important and can change the cross-section by as much as one order of magnitude. The amount of π⁺ηversus K ⁺ production is shown to depend critically on the primary mixture of the two mechanisms, with large interference effects due to final-state interactions. These effects are also shown to occur in the event distributions of invariant masses which are drastically modified by the final-state interactions of the two-meson or the d system. Received: 28 September 2001 / Accepted: 26 November 2001     

N＊（1535） contribution in pp →ppη＇ and pn →dφ

In an effective Lagrangian model we find that the N＊（1535） resonance contribution might be important to the interpretation of the present data of the pp →ppη＇ and pn →dφ reactions. The strong coupling strength of N＊ （1535） to η＇ and φ are indicated, and the possible implication to the intrinsic component of N＊（1535） is explored. These results may provide hints to the real origin of the OZI rule violation. It is stressed that further measurements could be performed at China. the Cooling Storage Ring （CSR） at Lanzhou of     

pp反应过程强子产生的不对称性

计算与分析了pp与p反应过程中轻味uds夸克的平均产生几率,得到它们与反应类型和反应能量的关系.进一步得出各种强子的相对产率,发现平均粒子产率,同位旋对称性,正反粒子多重数比例以及奇异抑制因子等,都与具体反应类型以及反应能量有关,特别得出pp反应中正反重子比率大于1 这与重离子碰撞实验结果非常吻合.     

多次散射理论与高能pp弹性散射

本文用复合粒子间的Glauber多次散射理论来分析高能pp弹性散射。假定质子由三个层子组成。且在入射弹为硬球近似下,层子在质子中形成简单的高斯分布,给出了一次、二次、三次……等多次散射振幅。并用这个结果计算了E_p=200、280、1500GeV的弹性散射角分布。结果表明高能量下的pp弹性散射可以视为层子与层子之间多次相干散射的结果。     

Revisiting the QCD Corrections to the R-Parity Violating Processes pp/pp → eμ ＋ X

We present the theoretical predictions up to QCD next-to-leading order for the cross section of high-mass electron-muon pair production at the Tevatron and at the Large Hadron Collider （LHC）, considering only the dominant contributions from the third-generation sneutrino. The dependence of the renormalization and factorization scales on the total cross section, and the effects on the K-factor due to the uncertainty of parton distribution function are carefully investigated. By considering soft-gluon resummation effects to all orders in as of leading logarithm, we present the transverse momentum distributions of the final eμ pair.     

FF模型在pp软碰中的应用

本文将夸克喷注的Field-Feynman模型推广应用到pp反应中, 并且提出一个关于双夸克碎裂的方案, 从而改进了A.Capella的双链模型. 这一图象既能给出各种粒子(介子, 重子, 光子, 夸克对等)的平均产额和能量的关系, 又能计算各种单粒子的内含谱及关联效应. 计算结果和实验数据符合很好.     

ψ′→pp角分布测量中的效率修正

利用参考衰变道J/ψ→pp的高统计量通过判选条件转换实现对ψ′→pp过程角分布测量中Monte Carlo效率的修正, 并对该方法可能带来的系统误差进行估计, 这些结果被用于ψ′→pp角分布的测量.     

NN巴黎势和可能的pp共振态

通过求解NN巴黎光学势的复薛定谔方程,研究了NN系统的近阈束缚和共振行为,得到了一个pp系统的13P0共振态.发现其能量和宽度与最近BES用Breit-Wigner(B-W公式分析J/ψ→γpp衰变的实验数据给出的结果相容.讨论了这一结果的含义及进一步研究的建议     

几何模型中的复数振幅和pp散射

把几何模型中散射振幅推广为复数型的散射振幅. 计算了s=540GeV的pp弹性散射. 解释了微分截面的形状和谷的位置.     

pp湮没成双介子的相对论处理

本文在³S₁模型基础上,采用相对论跃迁势和夸克(反夸克)旋量波函数,计算了pp→π⁺π^－和K⁺K^－的反应截面和角分布.     

The Linearσ-model and the Observed Enhancement in the Mass Spectrum of pp in J/ψ→γpp

Provided the enhancement in the pp spectrum in radiative decay J/ψ→γpp observed by the BES collaboration is due to an existence of a pp molecular state, we calculate its binding energy and lifetime in the linear σ model. Concretely, we consider a possibility that the enhancement is due to a pp resonance which is in either S-wave or P-wave structure and compare our results with the data. Moreover, pp can annihilate at s-channel which is absent in deuteron, thus by studying the total width of the pp bound state, we may gain more information about the linear σ model and some concerned issues