Study on the Structure of Hypernuclei ΛΛ5H,ΛΛ5He,ΛΛ4He and ΛΛ4H

In this paper, double Λ binding energies B_ΛΛ s of _ΛΛ⁵He(_ΛΛ⁵H), AA4He and _ΛΛ⁴H are calculated with the help of few-body models. The results show that stable binding state for _ΛΛ⁵H or _ΛΛ⁵He exists definitely with B_ΛΛ(_ΛΛ⁵H)=6.75MeV and B_ΛΛ(_ΛΛ⁵He)=7.67MeV,respectively. As to _ΛΛ⁴He and _ΛΛ⁴H, preliminary results indicate that _ΛΛ⁴H is unstable against decaying into Λ+_Λ³H, and _ΛΛ⁴He has no binding state.     

THE SU(6) “UNITARY ENERGY BAND” STRUCTURE IN THE TRIBARYON SYSTEM

A picture of the tribaryon system is proposed based on the papers [1—3]. It is considered that proton, neutron and A hyperon from the basic particles of SU(3) group and form the basic particles of SU(6) group on account for spin. It turns out that there exist "unitary energy band" structure in the tribaryon system. From the mass formula of T₃³ breaking, one can find that the SU(6) symmetry gives the mass relations between different spin levels of the same strangeness analog states. Finally, simple calculations are made and tbere is no discrepancy between tbe results and the experimental data.     

A STRUCTURE MODEL OF STRATONS AND LEPTONS

A subquark model is proposed. According to this model, stratons and leptons are consisted of rishons T and V, which are multiplets of group SU_H(3)×SU_C(3)×SU_G(2)×SU(2)×U(1). Three generations of both stratons and leptons are obtained naturally. In this model, proton decay modes are μ^－e⁺e⁺ or e^－μ⁺μ⁺.     

SU(3) LIMIT OF U(6/20) SUPERSYMMETRY IN NUCLEI

In this paper we discuss the SU(3) limit of U(6/20) supersymmetry. First we derive the reduction formulas of the relevant group chain. Then we discuss the dynamical symmetry. Finally we make comparison between the theoretical calculation and experimental measurement in the case of nucleus .²³⁵₉₂U₁₄₃     

Constraint on the warped space from B→X_sγ

We analyze the theoretical prediction on the branching ratio of B→X_sγ to order Λ_EW²/Λ_KK² in extension of the standard model with a warped extra dimension and the custodial symmetry SU(3)_c×SU(2)_L×SU(2)_R×U(1)_X×P_LR, where Λ_KK denotes the energy scale of low-lying Kaluze-Klein excitations and Λ_EW denotes the electroweak energy scale. Contributions from the in nite series of Kaluze-Klein excitations are summed over through the residue theorem. The numerical result indicates that the present experimental data constrain the parameter space of the concerned model strongly.     

AN SU（4）×S3a SCHEME OF THE STRATON MODEL

In this paper, we propose an SU（4）×S₃^a scheme of the Straton Model and discuss the classification of mesons. We suggest the possible existence of several colour excited states with masses around 2 GeV in companion with charm mesons. We also discuss the properties and the experimental behavior of these colour excited states, especially, the possible contribution of these states in several new phenomena.     

THE REGGE TRAJECTORY OF MESONS AND THE SU(4) MASS RELATIONS

A relativistic equation of motion of a two particle system under the constraints p_i²-m_i²-U(x²)=0.(i=1,2), where U(x²) is an infinite spherical square well poten-tial, is applied to the SU(4) quark model of mesons. A set of linear mass relations areobtained. Instead of the linear relation between J and M², the Regge trajectory ob-tained is a relation between p_nl² and M², where ζ_nlπ are zeros of the spherical Besselfunctions. The new trajectory seems more satisfactory than the former one.     

Hypertriton and light nuclei production at Λ-production subthreshold energy in heavy-ion collisions

High-energy heavy-ion collisions produce abundant hyperons and nucleons. A dynamical coalescence model coupled with the ART model is employed to study the production probabilities of light clusters, deuteron (d), triton (t), helion (³He), and hypertriton (_Λ³H) at subthreshold energy of Λ production (≈ 1 GeV per nucleon). We study the dependence on the reaction system size of the coalescence penalty factor per additional nucleon and entropy per nucleon. The Strangeness Population Factor (S₃ / (³He × (Λ/p))) shows an extra suppression of hypertriton comparing to light clusters of the same mass number. This model predicts a hypertriton production cross-section of a few μb in ³⁶Ar+³⁶Ar, ⁴⁰Ca+⁴⁰Ca and ⁵⁶Ni+⁵⁶Ni in 1 A GeV reactions. The production rate is as high as a few hypertritons per million collisions, which shows that the fixed-target heavy-ion collisions at CSR (Lanzhou/China) at Λ subthreshold energy are suitable for breaking new ground in hypernuclear physics.     

THE EFFECTS INDUCED BY A Λ HYPERON ON THE PAIRING CORRELATION IN NUCLEUS

In this paper, the effects induced by a Λ hyperon on the pairing correlation in nucleus are investigated. For simplicity, the δ-type A-N residual interaction is adopted. We have calculated the energy Spectrum and wave function of the low-lying excited states for _Λ¹⁰O. Then using infinite sum approximation, the correlation effect for two nucleons in the high energy shell induced by a Λ-hyperon is discussed.Finally. by means of Bose approximation, the correlation effects for n pairs of nucleons induced by a Λ is analysed.     

AN SU(4)×SU(2)×U(1) UNIFIED MODEL

In this paper we propose an SU(4)×SU(2)×U(1) unified model, in which the stratons and leptons of every generation belong to the same Multiplet, and the leptons will couple to the stratons. But this kind of coupling cannot cause the proton decay, and has only some effects in high energy scatterings. This model predicts the existense of two neutral intermediate bosons, instead of one, and the value of Weinberg angle to be sin²θ_w=0.25. The neutrinos have reasonable masses in the model.     

SU（4）×S3α SCHEME OF STRATON MODEL AND THE NEWLY DISCOVERED HEAVY PARTICLE γ（9.5）

In this paper, the possibility that the newly discovered heavy particle γ （9.5） is a colour excited state of mesons in the SU（4）×S₃^α scheme of straton model is discussed. We point out that in the γ region, there are three colour excited states appearing as two peaks with mass difference about 0.5 GeV. The leptonic decays, hadronie decays, radiative decays, hadronic decays with electromagnetic interaction of the second order and the production behavior of γ are discussed. This model also predicts that many colour excited states of mesons accompanied with γ should exist with masses around 9.5 GeV and at least four weakly decaying particles should exist.     

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.     

AN ANALYSIS OF FOUR-ELEMENT MODELS OF LEPTONS AND NON-DIAGONAL NEUTRAL CURRENTS

Due to the possible production of neutral and charge heavy leptons by v_μ, models consisting of four elements per "line", e.g. v_e, e^-, E⁰, E^- v_μ, μ^-, M^0, M^- v_τ, τ^-, T⁰, T^- ……are analysed. Non-diagonal neutral currents cannot be avoided. Nevertheless, a model is proposed within SU_（2）×U_（1） in which the process μ→eγ can still be suppressed by the Bjorken-Lane-Weinberg mechanism; various production cross-sections for heavy leptons are reasonable when compared with experiments. Models corresponding to SU_（3）×U（1） and still higher symmetries are discussed.     

WAVE FUNCTIONS WITHOUT SU6 SYMMETRY IN THE STRATON MODEL AND THEIR APPLICATIONS

On the basis of the straton model^[1],using the general groundstate wave functionsof mesons and baryons given in ref.[2],we have constructed under some specific as-sumptions the meson and baryon wave functions without SU₆ symmetry.We applythese wave functions to explain the mesonic and baryonic properties of the electroma-gnetic and weak interactions;many results obtained are in agreement with the experi-ments.By using the 1/2⁺-baryon wave functions without SU₆ symmetry,we obtain ananomalous magnetic moment for the proton.There is no need to introduce an ano-malous magnetic moment for the straton in the effective Hamiltonian of electromag-netic interaction between stratons.Similarly,the magnetic moment of the neutroncan also be explained.     

U(6/20) SUPERSYMMETRY IN NUCLEI AND ITS Spin (6) LIMIT

The U(6/20) supersymmetry is discussed in this paper. Particularly we discuss its Spin (6) limit. First we discuss the reduction of the group chain of the Spin(6) limit. Secondly we derive the wave functions and excited energy formulas for the nuclei in which the Spin(6) limit of U(6/20) supersymmetry exists. Thirdly we make comparison of the nuclear energy spectra between the theoretical calculation and experimental measurement in the case of nucleus ₇₇¹⁹³Ir₁₁₆. The comparison shows that the Spin(6) limit of U(6/20) supersymmetry possibly exists in nucleus ₇₇¹⁹³Ir₁₁₆.     

DISCRETE SYMMETRY AND SU(N) GRAND UNIFIED MODELS

Using discrete symmetry S, a systematic analysis of all possible GUT models based on the low rank group SU(N)×S is presented. It is found that only SU(7)×S and SU(8)×S are the satisfactory gauge groups of flavour grand unification. In addition, SU(7)×S and SU(8)×S models are discussed in detail. All these models can accommodate. four generations of ordinary fermions and preserve the asympotic freedom of SU_c(3).     

ΛΛ,ΛΛγ and ΛΛπ0 Productions in J/ψ Decay

The channels of J/ψ decay into,ΛΛ,ΛΛγ and ΛΛπ⁰ are analyzed with 7.8×10⁶ J/ψ events collected by BES detector at BEPC Collider.The branching ratios for three channels and the angular distribution for the first channel are measured.The branching ratios are Br(J/ψ→ΛΛ)=(l.08±0.06±0.24)×10^－3,Br(J/ψ→ΛΛγ)－4(90% CL)and Br(J/ψ→ΛΛπ⁰)=(2.3±0.7±0.8)×l0^－4 respectively. The angular distribution for J/ψ→ΛΛ is dN dcosθ=N₀(1+αcos²0),α=0.52±0.33±0.13.     

Quark-Chiral Field interaction in SU(3) Model

A quark-quark potential is derived from the linear expression of the Lagrangian Which is invariant under the SU(3)_L×SU(3)_R infinitesimal transformation,and further used to make a qualitative analysis on the Λ-N interaction.The result shows that the SU(3)chiral scalar fields are important in explaining the spin-dependence feature of the Λ-N interaction.     

UNIFIED ELECTRO-WEAK MODEL IN SU (3)

In this paper a unified electro-weak model for leptons based on the SU(3) gaugegroup is suggested by means of four kinds of realization for the generators of thegroup. For all low energy electro-weak processes, this model predicts the same resultsas the conventional Weinberg-Salam model does. The Weinberg angle is shown to be sin²θ_w=1/4 in a natural way. When the Higgs self potential respects a discrete symme-try Φ→-Φ, a new conserved quantum number called weak strangeness emerges fromthe model after spontaneous symmetry breaking. In the present model there existanother four heavy vector gauge bosons V^± and U^±± together with some heavyfermions and Higgs scalars, which have non vanishing weak strangeness quantumnumbers. These weak strange particles have no direct couplings with leptons. Theirexistence will not influence the low energy electro-weak processes. Nevertheless, theycan be produced in pairs in high energy collisions and the lightest of them should bestable if the conservation of weak strangeness is exact. The experimental implicationsand the possibility of violation of the conservation of weak strangeness are also dis-cussed.