On fermi quantum fields constructed from bose quantum fields and their applications

In former papers a representation of the quantum Fermi and para-Fermi fields was proposed. This representation is such that the only basic quantum entities are Bose quantum fields. In this paper we show several possibilities of application: (i) to lower the number of elementary particles; (ii) to describe as separate states of a fundamental particle other particles that presently are considered as different, and to induce an ordering among them; (iii) to obtain relations among the quantum numbers of those particles; (iv) to obtain a physical picture of some unstable particles. This article is concerned with the physical interpretation of the formalism, and some of the statements that are contained here have a conjectural character.     

Functional integration for Bose fields

The Lagrangian occurring in functional integration of bose fields is shown to be made up of two parts, one pertaining to the Bose commutation and the other to the dynamics.Supported by the U.S. Army Research Office (Durham).     

Canonical and microcanonical calculations for fermi systems

Recursion relations are presented that allow exact calculation of canonical and microcanonical partition functions of degenerate Fermi systems, assuming no explicit two-body interactions. Calculations of the level density, sorted by angular momentum, are presented for 56Ni. The issue of treating unbound states is also addressed.     

Hund's rules reformulated as inequalities and some related inequalities for exchange integrals,Slater-Condon parameters energy differences and correlation energies

Measurements have been made of the neutron scattering structure factors of liquid nitrogen and liquid oxygen at 77 K and 84 K respectively in the Q-value range of 3 to 36 Å^-1. ‘White’ incident thermal neutrons were produced in the wavelength range of 0·3 to 3·0 Å by a pulsed electron linac and detected in a total-scattering time-of-flight spectrometer. Qualitative agreement has been obtained between these present data and a simple molecular form factor in the Q-value range of 12–36 Å^-1.

Using reactor data [1], structure factors over a total Q-value range of 0·3 to 36 Å^-1 were obtained. Fourier transforms of the structure factor curves yield pair distribution functions which show a distinct separation of the inter and intra-molecular distances in the liquid. A comparison is made with results for the solid phase.     

Yano vector fields and conformally related spaces

We discuss some geometrical properties of Killing forms of order three and exhibit a procedure for constructing spaces admitting such tensors. As an example we prove that all conformally flat spaces admitting such a tensor are related to spaces of constant curvature.On leave April 1979 from the Service de Mécanique et Relativité Générales, Université de l'Etat à Mons, Belgium.     

Optimal electric fields for different sample shapes in high resolution NMR spectroscopy

For many applications, reducing sample resistance, rather than increasing probe Q or filling factor, is the only way to further improve the signal-to-noise ratio of cryogenically cooled NMR probes. In this paper, bounds are calculated for the minimum sample resistance that can be achieved for various sample geometries. The sample resistance of 100 mM NaCl in H(2)O in 5 mm sample tubes was measured on a 600 MHz cold probe to be within 14% of the optimum value. The minimum sample resistance can however be lowered by altering the tube cross section. Rectangular tubes oriented with the long axis along the RF magnetic field are particularly favourable.     

Optimal rotations of deformable bodies and orbits in magnetic fields

Deformations can induce rotation with zero angular momentum where dissipation is a natural "cost function." This gives rise to an optimization problem of finding the most effective rotation with zero angular momentum. For certain plastic and viscous media in two dimensions the optimal path is the orbit of a charged particle on a surface of constant negative curvature with a magnetic field whose total flux is half a quantum unit.     

Optimal conditions for observation of phonon echoes and amplification induced by alternating magnetic fields

Quantitative predictions are given for the observation of acoustic echo effects and amplification induced by alternating magnetic fields in a number of orderes magnetic insulators.     

Optimal control of shot noise and Fano factor by external fields

A method is devised to control the current, shot noise and Fano factor in a molecular junction using external fields. The tunneling of electrons through a molecular junction weakly coupled to two leads in the presence of a time-dependent external field is studied using a quantum master equation approach. By combining optimal control theory and assuming a predefined time-dependent current pattern, an external field can be determined which does generate a current pattern close to the requested one. With this approach the current flow pattern in time can be chosen in an almost arbitrary fashion. The same technique can be applied to control the shot noise. For minimizing the current, the corresponding shot noise decreases but does not vanish. By minimizing the shot noise, the corresponding current also approaches zero for the present model of spinless electrons. Within certain limits the proposed strategy even works well for the control of the Fano factor.     

Interplay between fermi surface topology and ordering in URu2Si2 revealed through abrupt hall coefficient changes in strong magnetic fields

Temperature- and field-dependent measurements of the Hall effect of pure and 4% Rh-doped URu2Si2 reveal low density (0.03 hole/U) high mobility carriers to be unique to the "hidden order" phase and consistent with an itinerant density-wave order parameter. The Fermi surface undergoes a series of abrupt changes as the magnetic field is increased. When combined with existing de Haas-van Alphen data, the Hall data expose a strong interplay between the stability of the "hidden order," the degree of polarization of the Fermi liquid, and the Fermi surface topology.     

Pauli principle sum rule and consistency relations for phenomenologically adjusted fermi liquid parameters

The sum rules for the Landau parameters which follow from the Pauli principle and the consistency relations between those parameters and the compressibility of nuclear matter and the symmetry energy are badly violated by the phenomenologically adjusted parameters used up to now. Here we show that all these relations can be nicely fulfilled if the one-pion-exchange and one-rho-exchange contributions are explicitly added to the l = 0 part (zero range) of the original Landau-Migdal interaction. It is important, however, to choose the particle-hole spectrum and the particle-hole interaction consistently.     

Cyclotron effective masses and fermi velocities for the ellipsoidal hole surfaces in molybdenum

We report on measurements of cyclotron effective masses and the dimensions k_a, k_b, and k_c for the hole ellipsoid, centered at the symmetry point N, of the Molybdenum Fermi-surface. Further, assuming parabolic band-structure, the Fermi-velocities for the holes are calculated for several crystallographic directions. The experimental measurements were performed both in a conventional reflection type experiment, and in a transmission type experiment, the latter being a new technique for observation of cyclotron resonance.     

Charge and/or spin limits for black holes at a non-commutative scale

We study the cosmological dynamics for R ^p exp(λ R) gravity theory in the metric formalism, using dynamical systems approach. Considering higher-dimensional FRW geometries in case of an imperfect fluid which has two different scale factors in the normal and extra dimensions, we find the exact solutions, and study its behaviour and stability for both vacuum and matter cases. It is found that stable solutions corresponding to accelerated expansion at late times exist, which can describe the inflationary era of the Universe. We also study the evolution of scale factors both in the normal and extra dimensions for different values of anisotropy parameter and the number of extra dimensions for such a scenario.     

基于声粒子分布积分的无网格声场计算方法

小尺度封闭空间内部声场的数值计算是声学设计、噪声控制等领域的关键技术。由于波动声学及几何声学方法计算频率上的限制,中频段声场计算问题一直是个难点。本文以声学无网格法为基础,提出了一种基于声粒子分布积分的无网格声场数值计算方法。文中利用声线跟踪理论计算声场中的声粒子分布,并以某个时间点上的声粒子作为蒙特卡罗法中的积分点,将其应用于无网格法中,从而获得声场中的节点声压。利用该方法对一个矩形封闭空间的中低频声场进行了计算,并与模态叠加法、商用声场计算软件、经典无网格法的结果进行了对比,证明基于声粒子分布积分的无网格声场数值计算方法在中低频段相较于传统基于网格的方法具有更高的精度。     

Phenomenological trends for heavy fermi liquids and narrow-band metals III: Characteristic temperatures

A correlation between the ratio of the Fermi temperature T_F¹ and the Debye temperature θ_D and the occurrence of superconductivity or magnetic order is described. Values of T_F¹/θ_D⪢ 1 are found to favor “conventional” superconductivity, whereas T_F¹/θ_D≲ 1 favors magnetic order. “Heavy fermion” superconductivity is found to be restricted to the case T_F¹/θ_D < 1.     

Finite size effects in euclidean lattice thermodynamics for non-interacting bose and fermi systems

In the Monte Carlo simulation of QCD, the euclidean form of the partition function is evaluated on a finite lattice. We use this method to calculate the partition function for non-interacting Bose and Fermi fields. Here the expressions on the lattice can be evaluated in closed form and the continuum limit is well-known; this provides us with a measure for finite lattice size effects in such approaches.     

Optimal heat kernel estimates for schrödinger operators with magnetic fields in two dimensions

Sharp smoothing estimates are proven for magnetic Schrödinger semigroups in two dimensions under the assumption that the magnetic field is bounded below by some positive constantB ₀. As a consequence theL∞ norm of the associated integral kernel is bounded by theL∞ norm of the Mehler kernel of the Schrödinger semigroup with the constant magnetic fieldB ₀.     

Symmetries and correlation inequalities for classicaln-vector models

We describe a new class of single spin measures on then-dimensional sphereS _r ⁿ of radiusr (n 4) for which Lebowitz-type [J. Lebowitz,J. Stat. Phys. 16:463 (1977)] inequalities hold. This is achieved by an appropriate parametrization ofS _r ⁿ . The above class includes the uniform measures onxs Rⁿ ¦x¦ r for any 0 p r. The second topic of this paper is an abstract formulation of the first Griffiths inequality [R. B. Griffiths,J. Math. Phys. 8:478 (1967)] and the underlying symmetry property.