1990 Vol. 14, No. 5
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The experimental method for spin-parity analysis of x in the radiative decay of J/ψ→γ+x has been studied with data generated by the Monte-Carlo method where x is a system of two pseudoscalars.As an example the results of J/ψ→γθ(1720),then θ(1720)→K－+K+ are presented.The uniqueness of valid theoretical hypothesis for various fitting results and the sensitive region of this method are discussed.
The practical emittance measurement of a Proton Linear Accelerator inevitably involves deformation.This paper suggests a syntactic pattern recognition method to handle the deformation problem.This approach consists of two steps.The first step is to use a use a sett of shape primitives to describe the contour of the emittance shape.The second step is to analyze the description syntactically.Syntax-Directed Translation scheme is employed to remove the deformation.
The problem of whether Feynman scaling exists or not in the fragmentation region of hadronic interactions at SppS energies is discussed.The evidences of scaling violation and to what extent the violation can reach are discussed.Several types of models commonly used in the investigation of cosmic ray superhigh energy phenomena are checked and discussed.
Based on the nontopological soliton model,a new picture for deconfinement transition is given.The relation between the existence of soliton solution and the nonlinearity of potential function is analysed.The effective potential and the equation satisfied by its extreme points are given at finite temperature.It turns out that,at critical temperature Tc,the physical vacuum is transformed into perturbative vacuum,soliton solution disappears and deconfinement phase transition occurs.
We argue from both the quark language and the free field light-cone expansion in light-cone perturbation theory that the constraint of overall "energy" conservation yields the same new scaling variable xp,which reduces to the Weizmann variable,the Bloom-Gilman variable and the Bjorken variable at some approximations.The xp rescaling is expected to be a good scaling variable,and hence gives substantial power-law type corrections to the deviations from the Bjorken scaling.Understandings of the xp rescaling from both the free field operator product expansion (OPE) and the ordinary OPE are also given,indicating that it is likely a higher order effect in the coefficient functions; i.e,it does not belong to the higher twist effect.Therefore this xp rescaling is a new effect contributing to the power-law type corrections,and hence is of substantial importance to the extraction of a reliable value of the QCD scale Λ from the data.
The independence or approximate independence of the multiplicity moments on energy,target mass and rapidity window in high enrgy nucleus-nucleus are analyzed.It is pointed out that all of these properties are due to the nuclear geometry.It is proved under very general conditions that,when the target mass is not extremely light and the rapidity window not very narrow,the normalized moments of the multiplicity are approximately equal to that of the number of participating nucleons.The calculated results for both minimum bias and central events agree well with the experimental data.
According to the phenomenological Λ-α interaction potential and the wave function of α- independent particle model of 12C and 16O,the analytical expressions for equivalent interaction potential of Λ-12C and Λ-16O are deduced,by using the folding potential method.Subsequently,the low-excited state energy of 13C and 17O and energy-level splitting of the first excited state of 13C caused by the spin-orbit coupling effect are calculated.And then the equivalent interaction potential of Λ-12C and Λ-16O and the structure of 13C and 17O are discussed.
The excitation functions are determined by activation method and stacked-foil technique for the 55Mn(α,n)58m,gCo,55Mn(α,2n)57Co and 55Mn(α,α′n)54Mn reactions from 10.4 to 26.5MeV.The experimental results are compared with theoretical calculation by exciton model.It is showed that preequilibrium emission reaction mechanism is present in these reactions.
Energy and angular correlation of α particles in coincidence with projectile-like fragments are measured.The coincident spectra of α particle indicate the sequential decay pattern of the projectile-like fragments and the target-like fragments.The energy correlation between projectile-like fragment 12C and α particles gives a strong evidence of projectile break-up.Near the direction of detected PLFS,the shadow effect is observed.
The variation of nuclear deformations with Z,N is studied with a two-level model with charge independent nucleon-nucleon interactions.Results obtained agree fairly well with observed ones.
The two-dimensional fission width in the quasi-stationary approximation is calculated by using the (c、h、α) parametrization.The difference between the two-dimensional and the one-dimensional cases is analyzed.
An expression for photon transmission coefficients in the resonance regions was given.The radiative neutron capture,which consists of both the statistical and nonstatistical contributions,for thirteen even-neutron nuclides in the 3s mass region were investigated in the resonance energy range less than 3MeV.
The possibility that ξ(2230) can be considered as a glueball is discussed in this paper.The ratios of the helicity amplitude are calculated.It is shown that ξ(2230) can not be a pure 2++ glueball in S wave (or D wave),but it can be a 4++ glueball in D wave.
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