1993 Vol. 17, No. 11
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The formalism and technique of the moment method for spin analysis of the boson X in J/ψ→γX,X→P1P2 are presented.The analysis technique is cited to study the spin of θ(1720) with Monte Carlo data samples.One finds that the spin of the boson X can be effectively determined by the moment method.As an example,the technique is used to measure the spin of the resonances in the low mass region of J/ψ→γK+K－ channel at BES.It is found that the spin analysis strategy of the moment method is successful.
The GdBa2(Cu1－xFex)3O7—δ system with x=0.005－0.001 and various oxygen concentrations was investigated by 57Fe-Mossbauer spectroscopy in temperature range 20K to 300K.The spectra of the orthorhombic phase were analyzed with four quadrupole doublets.Three of them were attributed to substitutional Cu(1) sites and one (with the smallest quadrupole splitting)to the substitutional Cu(2) site.From an analysis of temperature dependence of the relative site intensities,different local Debye temperature for the Cu(1) sites were derived.Highly texturized absorbers were investigated to study the polarization dependence of the four quadrupole doublets.Measurements at the magic angle gave evidence for a vibrational anisotropy (Goldanskii-Karyagineffect) of the Cu(1) sites.The Cu(1) site with the largest quadrupole splitting exhibited the lowest Debye temperature and the largest vibrational anisotropy.
Angular distributions of projectile fragments P,Si,Al and Mg produced in collisions of 200A GeV 32S beam with Cu are measured.The range of σpt deduced is within 130—270MeV/c.
The cross section is measured for 65 target residues produced from the interaction of indium with 42MeV/nucleon 12C ions using nuclear chemistry techniques.The experimental mass yield distribution gives a satisfactory agreement with that calculated from Monte Carlo code GEMINI based on the statistical binary decay model. According to the systematics of isotope distributions,the possibility of the production of new neutron-deficient nuclides far from β stability is discussed in the intermediate energy heavy ion reaction.
Activities of 183Os were produced by 39MeV α particles bombarding on a natural tungsten target.β+ spectrum with coincidence gate set on the strongest 382keV γ-rays of 183Os decay was measured.The endpoint energy of the β+ spectrum was determined and the QEC value of 183Os decay was extracted to be 2.24±0.10MeV which is in good agreement with the predicted value 2.30±0.10MeV on the basis of mass systematics.
The angular distribution for the process J/ψ→V1+X,X→γ+V2,V2→2P or 3P(where V1 and V2 stand for the vector mesons,P is the pseudoscalar meson) are presented.They can be used to distinguish the spin of the boson resonance X and determine the space parity in some special cases.
With the aid of imaginary time temperature field theory and fermion mass spectrum derived from Ward-Takahashi identities with composite fields,the vertex correction among fermions and σ meson is calculated beyond the leading order in 1/N expansion,and the change of vertex function with temperature and decoupling transition are discussed in (2+1) dimensional chiral Gross-Neveu model.It turns out that the critical temperature of decoupling transitionarises with increasing fermion mass and π meson mass at zero temperature;the vertex correction resulting from thermal fluctuation will affect the fermion dynamical mass and cannot be ignored at finite temperature.
The interaction vertices of the couplings of technivector mesons to the pseudoscalar mesons are derived from effective Lagrangian.We discuss all possible decay modes of neutral vector mesons and compute various decay factors.
We used the variational method in lattice gauge theory to calculate the chiral order parameter 〈ψψ〉 in the Schwinger model with Wilson fermions.
In this paper,the existence of bound state solution to Klein-Gordon and Dirac equations under the JBD Straight Cosmic String background is investigated.We prove the existence of such bound states,and point out that the number of which might be infinite.The location and spectrum of bound states of lower energy are calculated.The nearest bound state to string of meson is located within the region 10－13cm.For electron,the nearest one is located at 10－7cm,with orbit velocity 10－4c.The discoverv of quantum bound states mentioned might provide a new mechanism for the observation of the cosmic string.
The heavy-quarkonium nuclear bound states are recalculated by solving the Klein-Gordon equations.We find that the ηc(2980) can be bound in the nucleus.But the binding energies are in general quite different from that found by Brodsky et al.
By means of a generalized three-level solvable model,the self-consistent procedure for solving the Hartree-Fock(HF) equation is studied in some detail.It is pointed out that due attention must be paid for the multiplicity of solutions.Different criteria for the choice of an adequate solution are considered and discussed.Further,the reason of the sudden jump of the HF solution in certain force-parameter(FP) region,the stability of the HF solution and its dependence on FPs are investigated.
The process of the dynamical symmetry breaking in nuclear IBM system is studied by using the topological approach and laying stress on the singular behavior and origin of the energy levels of avoided crossing.It is shown that avoided crossing is really due to unstable fixed point of the dynamical mapping.Beyond such point,to perform the continuous mapping requires a localized permutation of the two levels concerned,and the mapping can no longer be expressible by the generators of the dynamical group.Thus,dynamical symmetry is localized and essentially destroyed.
All the data now available for the ground rotational bands of actinide even-even nuclei and rare-earth even-even nuclei are analyzed with eight formulas for rotational spectra.It can be seen from calculated results that the four-parameter I(I+1) expansion,the four-parameter ω2 expansion and W-Z formula can fit the GRB's of well-deformed unclei very well.
By utilizing the 1/N expansion technique(ONET),the analytical expressions of low-lying energy spectrum,the deformation parameter and the reduced matrix elements of E2 transitions to the order of 1/N are systematically given for a consistent Q framework in the sd interacting boson model.It is shown that it is important to consider the angular momentum projection in the intrinsic state formalism.
The natural Osmium powder was irradiated with fast neutrons.After the chemical separation,the characteristic gamma ray spectra and the time-sequential spectra in the W fraction were measured.11 new gamma lines os 189W unknown previously were found.
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