The Relation Between K+/π+ Ratio and Secondary Collisions in Ultra-Relativistic Heavy Ion Collisions

Based on the concep, t of the formation time, the contribution of secondary collisions to the change of the K⁺/π⁺ ratio in ultra-relativistic heavy ion collisions is calculated. The result shows that the effect of secondary collisions in the target nucleus is not enough to explain the observed change of the K⁺/π⁺ ratio.     

Enhancement of the K+/π+ Ratio in High-Energy Proton-Nucleus and Nucleus-Nucleus Collisions due to the Final State Interactions

The pion-meson secondary collisions with surrounding nucleons in the nucleus can influence the K⁺/π⁺ ratio. We calculate this effect in proton-nucleus and nucleus-nucleus collisions by the Glauber model and find that the final state interactions are important.     

Quasi Three-Body Decay of D Meson

The aim of this work is to provide a phenomenological analysis of the contribution of D~0 meson to K*(892)~0π~+π~-(K*(892)~0-→π~+K~-), K~-π~+ω(ω-→π~+π~-π~0) and K~-π~+?(?(1020)-→ K~+K~-) quasi-three-body decays. The analysis of mentioned multi-body decays is such as to factorize into the three-body decay and several channels observed. Hadronic three-body decays receive both resonant and non-resonant contribution. Based on the factorization method, there are tree and emission annihilation diagrams for these decay modes. In the case of D~0 to vector pseudoscalar states appeared in factored terms, the matrix elements of the vector and axial vector currents between the D~0 and PV mesons can be computed by using D~(*+)pole. Considering the non-resonant and resonant amplitude in our computation,the theoretical values of the branching ratio are(9.78 ± 0.46) × 10~(-3),(2.74 ± 0.17) × 10~(-2), and(3.53 ± 0.23) × 10~(-5), while the experimental results of them are(9.9 ±2.3) × 10~(-3),(2.7 ± 0.5) × 10~(-2), and(4 ± 1.7) × 10~(-5) respectively. Comparing computational analysis values with experimental values show that our results are in approximately agreement with them.     

The ρ-π Puzzle of J/φ and φ′ Decays

The recent BES Collaboration data on φ →PV, particularly the isospin violating mode φ′ → π^oω^o and finding of a finite number for B(φ′ → K^*OK^O), enable us now to deal more precisely about the challenges to theory concerning this extraordinary and remarkableso-called ρ-π puzzle of J/φ and φ′ decays. In terms of the existing data and deploying the simplest phenomenology, measurement of φ′ → π⁺π^- and whether a finite number for the K^*+K^- mode might require a significantly large accumulation of data remain interesting questions.     

Unconventional Medium Effect in K+-and π+-Nucleus Scattering

The ratios of total cross section of K⁺-nucleus to K⁺-deuterium at 400 MeV/c≤pk≤800 MeV/c for ⁶Li, ¹²C, ²⁸Si, ⁴⁰Ca and the differential cross section of π⁺-¹²C scattering at p_π= 800 MeV/c are calculated by taking into account the unconventional medium effect.An enhancement of both the K⁺-and π⁺-nucleus scattering cross sections is obtained.     

The Three-Pion Decays of the a1(1260)

We investigate the decay of a₁⁺ (1260)→π⁺π⁺π^- with the assumption that the a₁(1260) is dynamically generated from the coupled channel ρπ and KK^* interactions. In addition to the tree level diagrams that proceed via a₁⁺ (1260)→ρ⁰π⁺→π⁺π⁺π^-, we take into account also the final state interactions of ππ→ππ and KK→ππ. We calculate the invariant π⁺π^- mass distribution and also the total decay width of a₁⁺ (1260)→π⁺π⁺π^- as a function of the mass of a₁(1260). The calculated total decay width of a₁(1260) is significantly different from other model calculations and tied to the dynamical nature of the a₁(1260) resonance. The future experimental observations could test of model calculations and would provide vary valuable information on the relevance of the ρπ component in the a₁(1260) wave function.     

The Grin Alice Sees Is Not from Cheshire Cat RHIC-a Good Place for Observing Glueballs

In the recent study on the relativistic heavy ion collisions (RHIC), the crucial problem is how one can identify the formation of quark-gluon-plasma (QGP). In this paper, we find that the number of glueballs produced from QGP is sizable and definitely affect the flavor and rapidity distributions of mesons which finally reach detectors. We propose that RllIC would be a good candidate for observing glueballs. We also suggest that the recent K⁺/π⁺ ratio may not indicate the QGP formation.     

ξ(2230) Is Likely to Be a Glueball

On the basis of the recent results of ξ(2230) → π⁺π^-, pp and ξ(2230) → K⁺K^-, K_sK_s, measured by the BES Collaboration in J/ψ radiative decays, combined with the PSI85 experiment of pp → ξ(2230) → KK we argue that because of its very narrow partial decay widths to nn and KK (less than 1 MeV), its large production rate in J/ψ radiative decays (BR(J/ψ → γξ> 2.3×10^-3), and its flavor-symmetric couplings to ππ and KK, the ξ(2230) is very likely to to be a J^PC= (even)⁺⁺ glueball.     

ON THE REACTION MECHANISM AND THE SELECTION RULE IN THE DOUBLE CHARGE EXCHANGE REACTION OF PIONS ON NUCLEI (DCX)-A STUDY OF THE CONNECTION BETWEEN THE 2β-DECAY AND DCX ON jP=O+ NUCLEI

It is shown that in the pion induced double charge exchange reaction on J^p=O⁺→O⁺ nuclei,there exists a possible new reaction mechanism π⁺(Δ⁰,Δ⁺⁺)π^- or π⁺(Δ^-,Δ⁺)π^- in so-called single step process,while that old speculative mechanism π⁺(N,Δ)π^- or π⁺(N,Δ)π^- is firbidden by a well-known selection rule which has been indicated in the theory of the nuclear 2β-decay.     

Vacuum Polarization Bubble Effects on the Triangle Relations for B Meson Charmless Decay Amplitudes

Assuming that factorization is valid and that contributions of the exchange, annihilation, and penguin-annihilation diagrams are negligible, we study the effects of the QCD vacuum polarization bubbles on the decay amplitudes of some B meson charmless decays into two light pseudoscalars. The bubbles have much less effects on B⁰→π⁺π^-, π^-K⁺, π⁰K⁰ than on B⁰→π⁰π⁰ thus the triangle relation √2A(B⁺→π⁺π⁰) = A(B⁰→π^-K⁺)/R_u+√2A(B⁰→π⁰K⁰)/R_u is changed slightly while √2A(B⁺→π⁺π⁰)=√2A(B⁰→π⁰π⁰)+A(B⁰→π⁺π^-) is altered significantly. This may indicate that in order to test or use these triangle relations other higher order QCD corrections should also be carefully taken into consideration.     

The Role of a1(1260) in π-p→a1-(1260)p and π-p→π-ρ0p Reactions Near Threshold

We report on a theoretical study of the π^-p→a₁^-(1260) p and π^-p→π^-ρ⁰p reactions near threshold within an effective Lagrangian approach. The production process is described by t-channel ρ⁰ meson exchange. For the π^-p→π^-ρ⁰p reaction, the final π^-ρ⁰ results from the decay of the a₁(1260) resonance, which is assumed as a dynamically generated state from the K^*K and ρπ coupled channel interactions. We calculate the total cross section of the π^-p→a₁^-(1260)p reaction. It is shown that, with the coupling constant of the a₁(1260) to ρπ channel obtained from the chiral unitary theory and a cut off parameter Λρ~1.5 GeV in the form factors, the experimental measurement can be reproduced. Furthermore, the total and differential cross sections of π^-p→a₁^-(1260)p→π^-ρ⁰p reaction are evaluated, and it is expected that our model calculations can be tested by future experiments. These reactions are important for the study of the a₁(1260) resonance and would provide further constraints on the properties of the a₁(1260) state.     

The New Clue to Understanding fo(975) Meson From Ds Decays

Based on the understanding of nonleptonic decays of charmed meson, the relative ratio Br(D_s⁺→f₀(975)π⁺/Br(D_s⁺→фπ⁺) is calculated. We argue that only (ss) component of f₀(975) contributes to it dominantly. The numerical result proves f₀(975) to be almost a pure (ss) state if the newly measured resultant value of the decay is trustable, and the conclusion is very usefulinformation as a clue for clarifying up the puzzle of 0⁺⁺ meson f₀(975).     

Yangian代数在混合介子态的纠缠和衰变中的应用

Yangian代数是超出李代数更大的无穷维代数,是研究非线性量子完全可积系统的新对称特性的有力数学工具.基于介子态中夸克-味su(3)对称性和Yangian代数生成元的跃迁特性,本文研究了Yangian代数Y(su(3))生成元在三种正反介子态(π~±,K~±,K~0和K~0)各自组成的三种混合介子态(π,K和K_i~0)衰变中的作用.将Y(su(3))代数的八个生成元(I~±,U~±,V~±,I~3和I~8)作为跃迁算子,作用在混合介子态上,研究其可能的衰变道,以及衰变前后纠缠度的变化.结果表明:1)在李代数范围内的生成元I~3和I~8作用下,三种混合介子态衰变后组成成分没有发生变化,其中混合介子态π在I~8作用下衰变前后纠缠无变化,其他衰变纠缠度发生了变化;2)在其他的六个(I~±,U~±和V~±)超出李代数的生成元的作用下,三种混合介子态衰变前后组成成分发生了变化,其中两个衰变后变成单态,纠缠度为零;两个衰变不存在;剩余两个衰变后纠缠度发生了变化,此外在带电(K)和中性(K_I~0)两类K型混合介子态的六种可能的衰变中,两种类型的末态的纠缠度两两相同;3)三种混合介子态之间可以通过I~±,U~±和V~±算子循环转化,具有明显的对称性.本文从具有的对称性上提供了一种探索混合介子态可能衰变的方法,并且可以用此方法去预测可能的未知衰变粒子和解释己测得的衰变问题.     

Experimental study of the time-dependent rate of K → πππ

The time-dependence of the decay rate of initially pure K⁰ into the final state (π⁺π⁻π⁰) has been studied in search for the decay k_S⁰→π⁺π⁻π⁰. No evidence is found in a sample of 384 observed events. The ratio of the CP -violating K_S⁰ amplitude and the K_L⁰ amplitude is η₊₋₀ = (0.13_−0.20^+0.17) + i(0.17_−0.26^+0.27); the ratio of the CP-conserving K_S⁰ amplitude and the K_L⁰ amplitude is < 0.4. The energy dependence of the K⁰→π⁺π⁻π⁰ matrix element is found to be a₊₋₀ = −0.31 ± 0.03.     

THE EXCITATION OF 9.5 MeV LEVEL OF 13C IN QUASI-Δ33 DOORWAY STATE MODEL

We have studied the excitation mechanism of 9.5 MeV Level of ¹³C in ¹³C(π^±,π^1±)¹³C (9.5 MeV) inelastic scattering in the framework of Quasi-X33 Doorway State. Model .Assuming. the transition to 9.5 MeV state is of a pure neutron has received satisfactory agreement with experiment. The results strongly suggest that the spin and parity assignment of state,9.5 MeV of ¹³C should be Jπ=9/2⁺.     

Charmless Hadronic Decays B→VV in the Topcolor－Assisted Technicolor Model

Based on the effective Hamiltonian with the generalized factorization approach, we calculate the branching ratios and CP asymmetries of B→VV decays in the Topcolor-assisted Technicolor (TC2) model. Within the considered parameter space we find that: (a) for the penguin-dominated B→K^*+φ and K^*0φ decays, the new physics enhancements to the branching ratios are around 40%; (b) the measured branching ratios of B→K^*+φ and K^*0φ decays prefer the range of 3≤N_c^eff≤5; (c) the SM and TC2 model predictions for the branching ratio B(B⁺→ρ⁺ρ⁰) are only about half of the Belle's measurement; and (d) for most B→VV decays, the new physics corrections on their CP asymmetries are generally small or moderate in magnitude and insensitive to the variation of m_π and N_c^eff.     

Determination of the K(1800) spin parity

A spherical harmonic moment analysis of the reactions K⁻p → K⁻π⁺n and K⁺p → K⁺π⁻Δ⁺⁺ at 13 GeV/c demonstrates the existence of a broad K^* state with mass in the vicinity of 1800 MeV and spin parity 3⁻.     

Gluonia and Charmonium Decays

We discuss the search for a 1^-- gluonium state, 0, in connection with a possible solution for the so-called ρπ, K^*K puzzle in the J/φ and φ' decays. Some issues are examined. In particular, we argue that the expected most favorable process φ → ππO can have an appreciable branching ratio (say 10^-3 ~ 10^-4) only if the O has a very narrow partial decay width to ρπ (say 1 ~ 10 MeV). For the 0^-+ system we deduce a relation that BR(η'_c → h) ≈ BR (η_c → h), where h denotes an exclusive light hadronic channel. This relation may be useful for the experimental search of the yet to be confirmed q: state, for which the branching ratios of φ' → η'_c → γKKπ, γηππ, γη'ππ are estimated to be about 1 × 10^-4 if the mass of η'_c is around 3600 MeV, and this relation may also serve as a criterion to determine whether there exist anomalous decays in the η_c and η'_c system, in particular in the VV decay channels, which might be related to the 0^-+ glueball-charmonium mixing. We emphasize that the bigluonium and the trigluonium may have very different effects on these decays.