Charm production in fixed target experiments

Prompt lepton production in proton beam dump experiments has been critically analysed within the general frame work of \(A_c \bar D\) and \(D\bar D\) production and their subsequent semileptonic decays. Realistic decay modes based on recent experiments are used. We have investigated the effect of using differentx dependences for the charm particles obtained either from simple quark counting rules or as inferred from strange particle production data. The \(D\bar D\) production is assumed to have a linearA dependence and for the \(A_c \bar D\) process bothA ¹ andA ^2/3 dependence is used. We show that by a simultaneous fit to the energy and angular distributions of prompt leptons in all the experiments the ratio of \(A_c \bar D\) to \(D\bar D\) production cross section can be determined. A comparison of this fit with these experimental distributions indicates that thex dependences based on strange particle data are strongly favoured. AnA ^2/3 dependence for \(A_c \bar D\) production, which corresponds to a quasi-diffractive process, is favoured although within existing errorsA ¹ dependence cannot be ruled out. Putting together the cross section results from our analysis with other results at similar energies (p _1ab ～400GeV/c) the production cross sections ( \(A_c \bar D\) ) and ( \(D\bar D\) ) are estimated to be ～25 and ～20 μb/nucleon respectively leading to a total inclusive charm cross section of ～90 μb/nucleon.     

螺纹管内污垢热阻的对比实验研究

本文对一冷却塔中的7根螺纹管进行了长时间污垢实验研究.螺纹管几何参数范围:螺纹数18～45,螺纹角25°～45°,螺纹高0.33～0.55 mm.污垢是颗粒污垢和析晶污垢的混合物.本文基于普朗特类比,引入修正因子β(β=(A_w/A_(wp))/(A_c/A_(cp)),A_w为润湿面积,A_c为截面积,下标p表示光管),对半经验污垢预测模型进行修正,证明了螺纹管内参数对污垢热阻的形成影响很大,并建立了不同结构参数的螺纹管的统一结垢模型,对工程实际有一定指导意义.     

On the Importance of Testing Gravity at Distances Less Than 1cm

If the mechanism responsible for the smallness of the vacuum energy is consistent with local quantum field theory, general arguments suggest the existence of at least one unobserved scalar particle with Compton wavelength bounded from below by one tenth of a millimeter. We show that this bound is saturated if vacuum energy is a substantial component of the energy density of the universe. Therefore, the success of cosmological models with a significant vacuum energy component suggests the existence of new macroscopic forces with range in the sub-millimeter region. There are virtually no experimental constraints on the existence of quanta with this range of interaction.     

Pion condensation in a relativistic field theory consistent with bulk properties of nuclear matter

Pion condensation has not previously been investigated in a theory that accounts for the known bulk properties of nuclear matter, its saturation energy and density and compressibility. We have formulated and solved self-consistently, in the mean field approximation, a relativistic field theory that possesses a condensate solution and reproduces the correct bulk properties of nuclear matter. The theory is solved in its relativistically covariant form for a general class of space-time dependent pion condensates. Self-consistency and compatibility with bulk properties of nuclear matter turn out to be very stringent conditions on the existence and energy of the condensate, but they do allow a weak condensate energy to develop. The spin-isospin density oscillations, on the other hand, can be large. It is encouraging, as concerns the possible existence of new phases of nuclear matter, that this is so, unlike the Lee-Wick density isomer, that appears to be incompatible with nuclear matter properties.     

Existence of Multi-string Solutions of the Gauged Harmonic Map Model

The gauged harmonic map model is coupled with gravity in (2 + 1)-dimensional Minkowski space. We prove that the existence of finite energy solutions of the model for arbitrary location of strings for small gravitational constant. We also prove the energy is quantized, while the magnetic flux may assume any prescribed value in an open interval, and is not quantized.     

On the correct interpretation of the energy levels' shifts in the presence of magnetic fields

It is shown that the concept of the existence of “potential energy of interaction” of the orbital magnetic moment of a charged particle with the magnetic field is not correct.     

The positron-helium bound state

A variational calculation with a trial wave function including up to 17 parameters has been used to investigate the existence of a positron-helium bound state. The resulting binding energy was found to be greater than the helium binding energy, and thus it is believed that the positron does not get bound to a helium atom. The calculations provide also values of ground state helium energy and the corresponding wave functions.     

Isotropic fluid phases of dipolar hard spheres

Monte Carlo simulations are used to calculate the equation of state and free energy of dipolar hard sphere fluids at low temperatures and densities. Evidence for the existence of isotropic-fluid-isotropic-fluid phase transitions is presented and discussed. Condensation in the dipolar hard sphere fluid is unusual in that it is not accompanied by large energy or entropy changes. An explanation of this behavior is put forward.     

Introduction to an analysis of kinematical exciton levels

The possibility of the existence of kinematical levels for a multi-level exciton scheme is analysed and it is shown that such levels exist for all the values of the wave vector. This is the consequence of the fact that the exciton gap is much larger than the energy bandwidth. The existence of kinematical levels is proved using a more correct method of decoupling of higher order Green's functions in which pairing is performed not only for the same moments of time but for different moments as well. A matrix formulation of the system of equations for Green's function is proposed and the analysis is performed in this condensed form representing a sensible simplification which could be helpful for the analysis of other multilevel excitation systems, too.     

Multiplicity distributions in the eikonal model

Explicit formulas for the generating function, topological cross sections and multiplicity moments are obtained in the eikonal model with a single Regge trajectory. The existence of Koba-Nielsen-Olesen (KNO) scaling in this model is discussed. It is shown that strict KNO scaling is not valid. However, there exists a limited range of energy where KNO scaling takes place approximately.     

Global Well-Posedness Issues for the Inviscid Boussinesq System with Yudovich’s Type Data

The present paper is dedicated to the study of the global existence for the inviscid two-dimensional Boussinesq system. We focus on finite energy data with bounded vorticity and we find out that, under quite a natural additional assumption on the initial temperature, there exists a global unique solution. No smallness conditions are imposed on the data. The global existence issues for infinite energy initial velocity, and for the Bénard system are also discussed.     

Stability of Quantum Systems at Three Scales: Passivity, Quantum Weak Energy Inequalities and the Microlocal Spectrum Condition

Quantum weak energy inequalities have recently been extensively discussed as a condition on the dynamical stability of quantum field states, particularly on curved spacetimes. We formulate the notion of a quantum weak energy inequality for general dynamical systems on static background spacetimes and establish a connection between quantum weak energy inequalities and thermodynamics. Namely, for such a dynamical system, we show that the existence of a class of states satisfying a quantum weak inequality implies that passive states (e.g., mixtures of ground- and thermal equilibrium states) exist for the time-evolution of the system and, therefore, that the second law of thermodynamics holds. As a model system, we consider the free scalar quantum field on a static spacetime. Although the Weyl algebra does not satisfy our general assumptions, our abstract results do apply to a related algebra which we construct, following a general method which we carefully describe, in Hilbert-space representations induced by quasifree Hadamard states. We discuss the problem of reconstructing states on the Weyl algebra from states on the new algebra and give conditions under which this may be accomplished. Previous results for linear quantum fields show that, on one hand, quantum weak energy inequalities follow from the Hadamard condition (or microlocal spectrum condition) imposed on the states, and on the other hand, that the existence of passive states implies that there is a class of states fulfilling the microlocal spectrum condition. Thus, the results of this paper indicate that these three conditions of dynamical stability are essentially equivalent. This observation is significant because the three conditions become effective at different length scales: The microlocal spectrum condition constrains the short-distance behaviour of quantum states (microscopic stability), quantum weak energy inequalities impose conditions at finite distance (mesoscopic stability), and the existence of passive states is a statement on the global thermodynamic stability of the system (macroscopic stability).Max-Planck-Institute for Mathematics in the Sciences, Inselstr. 22, 04103 Leipzig, Germany. verch@mis.mpg.de     

热力学平衡态的涨落判据

任何热力学量的涨落在平衡态下都不能太大.特别地,要求熵和能量的涨落不大,就可以给出低温下热力学平衡态的普遍适用的判据.一些算例表明,低温下即使1023个粒子也不一定能达到热力学平衡态.     

Plasmon photoelectric effect from alkali halides

The existence of the plasmon photoelectric effect was postulated elsewhere by one of the authors. In the plasmon photoelectric effect, incident photons excite plasmons in the solid; the decay of plasmons excites electrons. The emergence of these electrons from the solid is responsible for a group of photoelectrons of definite energy. The existence of the plasmon photoelectric effect is confirmed by comparison of spectral photoelectric yield data with electron energy loss spectra in 16 alkali halides. The presence of the plasmon photoelectric effect explains additional peaks observed with some alkali halides in the energy spectra of photoelectrons. These peaks were not understood previously.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 7–16, October, 1974.     

有限宽度布拉格原子层中光子囚禁与移动孤子的研究

研究二能级原子层宽度对一维共振吸收布拉格反射镜中自感应透明光孤子形成的影响.结果表明：在有限宽度的二能级原子层中仍可激发稳定的移动孤子，其激发条件对原子层宽度依赖不大；然而静止孤子的存在条件却敏感地依赖于原子层的宽度，二能级原子层宽度只有小于某一特定值时，光脉冲才能演化成静止孤子. 关键词： 有限宽度 周期结构 移动孤子 静止孤子     

Photon-Solitons and Some Experimental Possibilities

In this paper we show that the possible existence of the photon as a soliton [1] can be studied with the help of well-known experimental results and we propose some new experiments which can help to examine some properties of the soliton. First, we compare the soliton energy density to the energy density of Planck and we show that the two densities are consistent. Second, we make an attempt to explain some old experiments with our soliton model of the photon and we show that the results of such experiments do not contradict the existence of such solitons. We also discuss the possibilities for new, improved experiments, which can help to distinguish the soliton interaction from the interaction of a classical electromagnetic wave with charged particles.     

A scalar polynomial singularity without an event horizon

It is shown that the solution of the field equations for a static spherically symmetric scalar field has a scalar polynomial singularity and no event horizon. The solution does not develop from nonsingular data on any Cauchy surface. The possible existence of a universal scalar field, the conformal diagram and geodesies of the solution, and the energy and momentum of the field present are discussed.     

Use of catastrophe theory to obtain a fundamental understanding of elementary particle stability

Using Arnold's Classification Theorem applied to a four-dimensional manifold, it is shown that there is only a finite number of ways in which energy can discontinuously change state. It is demonstrated that each of these energy flow pathways can be associated with a distinct elementary particle. The theory not only shows how the formation of particles from the stress-energy present in the space-time manifold can be predicted from first principles, but also that there must exist five fundamental forces in a universe in which discontinuous energy transitions are possible. Finally, the existence of a new, as yet undiscovered particle is predicted, which is associated with this new fifth force.     

Instability of the Kaluza-Klein vacuum

It is argued that the ground state of the Kaluza-Klein unified theory is unstable against a process of semiclassical barrier penetration. This is related to the fact that the positive energy conjecture does not hold for the Kaluza-Klein theory; an explicit counter-example is given. The reasoning presented here assumes that in general relativity one should include manifolds of non-vacuum topology. It is argued that the existence of elementary fermions (not present in the original Kaluza-Klein theory) would stabilize the Kaluza-Klein vacuum.