1987年, 第8卷, 第2期　
刊出日期：1987-09-15

  

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  ON CALCULATION OF THE HYDROGEN NEGATIVE ION BETA SPECTRUM

  赵小麟

  理论物理通讯. 1987, 8(2): 127-137.

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  The wavefunctions of the gxound states of negative hydrogen ion and the 10 first lowest ¹S states of helium atom are calculated by using a general wavefunction expansion form.The beta spectrum of the negative tritium ion is given by calculating a few most important transitions and including the remainder in terms of the closure approximation. Besides,the transition to ¹S(2S²) state is also studied.The result showed that the transition to a double-electron excited state of the helium atom may be very important. It indicates that there probably exists a resonance in the continuous spectrum.
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  ISOMERSHIFT CALIBRATION OF Fe NUCLEUS BY SELF-CONSISTENT ALL-ELECTRON LAPW BAND CALCULATION

  张齐鸣, 张玉林, 王鼎盛

  理论物理通讯. 1987, 8(2): 139-151.

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  Accurate band calculation for α-Fe is used to determine the isomershift calibration of Fe nucleus.The semi-relativistic, all-electron, self-consistent Iinearized augmented planewaye (LAPW) method is employed in band calculations for lattices with different spacings. The ratio of the calculated difference of the electron contact density to the volume change, and the experimental pressure dependence of the isomer- shift are used to deduce the calibration constant. The result thus obtained to be-0.26±0.02mm.sec^-1(au)³,is in good agreement with the recent cluster calculation.The screening effect is shown to play an essential role,and the necessity for an all-electron self-consistent calculation is emphasized.
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  STEADY SIATE SOLUTIONS OF THE FOKKER-PLANCK EQUATIONS

  郑强, 郝柏林

  理论物理通讯. 1987, 8(2): 153-166.

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  A new way of constructing the steady state solutions of the Fokker-Planck Equations(FPE's) is described in which the concept of a vortex field h plays an important role.The steady state solutions can be classified according to the type of h.In particular, one easily obtains almost all the exact global solutions known so far for the stationary FPE's, as well as the exact local solutions near the fixed points of the corres-ponding deterministic equations.In this way some new properties of FPE are explored.
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  HYDRODYNAMIC STABILITY OF TWO-COMPONENT FLUID HEATED FROM BELOW AND WITH SURFACE ADSORPTION

  褚小麟, 陈燎原

  理论物理通讯. 1987, 8(2): 167-177.

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  The stability of a two-component Benard fluid with surface adsorption in reduced- gratuity condition is examined by using linear stability analysis. Results show that the surface tension effect of the active solute plays a dual role on the stability of the fluid, A few dimensionless combinations are introduced to delimit the regions where the stabilizing or destabilizing role, or both, of the solute tension come into plan.
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  BENARD CONVECTIVE INSTABILITIES OF A TWO-COMPONENT FLUID SYSTEM WITH SURFACE CHEMICAL REACTION

  陈燎原, 褚小麟

  理论物理通讯. 1987, 8(2): 179-186.

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  A new model of Benard instability problem in the presence of surface chemical reaction and a sufficient instability condition as follows from the classical linear stability analysis are presented.
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  THE NUCLEAR DROPLET MODEL FOR ARBITRARY NEUTRON EXCESS

  王正行

  理论物理通讯. 1987, 8(2): 187-209.

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  The Myers and Swiatecki's droplet model is extended to the case of very neutron rich nuclei which,in the case of small neutron excess,can be reduced to the usual droplet model with a small difference which comes from the different considera-Lions on the surface energy.The bulk energy den-sity and the superficial energy density are taken from the earlier calculations based on the Thomas-Fermi model with Seyler-Blanchard interaction. The approximate formulas are obtained for the nuclei with small neutron excess.The comparisons between the nucleon distributions calculated by this model and by Thomas-Fermi model are made for both the uncharged and the charged nuclei and a satisfactory agreement is obtained.The comparison between the results calculated by this model and by its approximate formulation for the nuclei with small neutron excess shows that the usual droplet model works very well in the sense of this comparison. The comparison. with the results calculated by other authors is also made.
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  THE CRITERION FOR FRACTIONAL CHARGE OF(1+1)-DIMENSIONAL DIRAC FIELD

  倪光炯, 汪荣奉

  理论物理通讯. 1987, 8(2): 211-228.

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  The fractional fermion number (charge) of (1+1)-dimensional Dirac field interacting with a scalar background field is investigated. By means of the correspondence principle in (1+1)-dimensional field theory,it is shown that only when the background field develops a solitvn with a node can the fractional fermion number be induced(node theorem).Consistently, a zero mode bound state of the fermion field should be present and responsible for the fractional charge as long as the soliton satisfies certain conditions (theorem of zero mode).We have also obtained the analytical expression of the vacuum charge distribution in the vicinitu of distorted reqion.
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  DIQUARK AND △-N MASS DIFFERENCE IN LATTICE GAUGE THEORY

  郭硕鸿, 陈启洲

  理论物理通讯. 1987, 8(2): 229-238.

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  We show that the spontaneous breaking of the chiral symmetry provides a mechanism for lowering the effective mass of spin zero diquark.relative to spin one diquark.This mechanism accounts for the main part of △-N mass difference. Lattice calculation is consistent with the quark-diquark structure of the nucleon.
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  THE n-p MASS RATIO IN QCD SUM RULES

  刘觉平

  理论物理通讯. 1987, 8(2): 239-253.

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  The QCD sum rules for the proton. mass,the n-p mass ratio and the optimal observation point are analysed, which can greatly improve the precision of the theoretical results. If we take =

  and m_u/(m_u+m_d)-=0.35 which agree with the values from SVZ and current algebra^[1,2],we obtain M_p=935.86MeV and M_p/M_n=0.99871 which coincide quite well with experimental values.The isospin behavior of light quarks is investigated. It shows that the isospin symmetry of the light quark condensates is very good up to the low-energy region (about 500MeV),and that the n-p mass difference can be originated from the u-and d-quark mass differences.