Streamer radius model and its assessment using two-dimensionalmodels

The variable radius method is proposed to approximate the radius of the ionization channel in the one and a half-dimensional (1.5-D) fluid models for studying streamer development, in which the unreasonable constant radius in the traditional 1.5-D fluid models is corrected. The streamer development and propagation between the 1.5-D fluid model with the variable radius method and the two-dimensional (2-D) fluid model using the same initial and external conditions are compared. The radius in each stage of streamer development from the 1.5-D fluid model with the variable radius method shows agreement to a certain degree with that of the 2-D fluid model. The purpose of this paper is not to negate the role of the 2-D fluid models, but to explore the potential of the 1.5-D fluid models and make them more useful and accurate as well as to understand the evolution of streamer radius. The streamer development from the 1.5-D fluid model with the variable radius method not only maintains simplicity of the 1.5-D fluid models, but also presents agreement with the 2-D fluid models for streamers     

Limit of Quasilocal Mass at Spatial Infinity

We study the limit of quasilocal mass defined in [4 and 5] for a family of spacelike 2-surfaces in spacetime. In particular, we show the limit coincides with the ADM mass at spatial infinity. The limit for coordinate spheres of a boosted slice of the Schwarzchild solution is computed explicitly and shown to give the expected energy-momentum four-vector.     

The Rest Mass of (Charged) Leptons in 6-D Spacetime

Starting from a model of the electron in 6-D spacetime which has been shown to give rise to the right values for spin and magnetic moment, if subject to an attractive potential due to vacuum polarization, the quantization of charged lepton masses is obtained with the additional hypothesis that a virtual pair of particles is created in the time subspace. This hypothesis suggests an infinity of charged leptons, each one in turn fixing the mass of a lighter one.     

Ornstein-Uhlenbeck Limit for the Velocity Process of an N-Particle System Interacting Stochastically

An N-particle system with stochastic interactions is considered. Interactions are driven by a Brownian noise term and total energy conservation is imposed. The evolution of the system, in velocity space, is a diffusion on a (3N?1)-dimensional sphere with radius fixed by the total energy. In the N→∞ limit, a finite number of velocity components are shown to evolve independently and according to an Ornstein-Uhlenbeck process.     

The Equivalence Principle in the Theory of Variable Rest Mass with Applications in Astrophysics

Russian Physics Journal - A covariant equation of motion and energy of a body with variable rest mass with dark energy taken into account in the general theory of relativity is considered on the...     

星系普查确定中微子总质量新的上限

剑桥大学Ｏ .Ｅｌｇａｒｏｙ等 30名英、澳、美学者应用 2度场星系红移普查 (2ｄＦＧＲＳ)数据将中微子总质量上限确定到不及 10亿分之一的氢原子质量 .这是当前最严格的中微子质量上限 .中微子有无质量一直是个不解之谜 .最近几年里 ,大气中微子实验和太阳中微子实验在这个方向上取得了引人注目的进展 .今年 3月 ,Ｓｕｄｂｕｒｙ中微子天文台 (ＳＮＯ)的观测更进一步提供了有力的证据 ,表明中微子有质量已是不争的事实 .但是 ,实验至今仍旧无法测出它们的绝对质量 .2ｄＦＧＲＳ是当前规模最大的星系普查 ,业已观测了 2 2万个以上的星系红移…     

The Hydrodynamic Limit of a Deterministic Particle System with Conservation of Mass and Momentum

We study the hydrodynamic limit of a deterministic one-dimensional particle system with nearest neighbour interaction and an additional regularizing force. Under its evolution mass and momentum are conserved. In the limit with Euler scaling their macroscopic distributions are shown to be governed by the compressible Navier–Stokes equations with a density dependent viscosity.     

On the Small Mass Limit of Quantum Brownian Motion with Inhomogeneous Damping and Diffusion

We study the small mass limit (or: the Smoluchowski–Kramers limit) of a class of quantum Brownian motions with inhomogeneous damping and diffusion. For Ohmic bath spectral density with a Lorentz–Drude cutoff, we derive the Heisenberg–Langevin equations for the particle’s observables using a quantum stochastic calculus approach. We set the mass of the particle to equal \(m = m_{0} \epsilon \), the reduced Planck constant to equal \(\hbar = \epsilon \) and the cutoff frequency to equal \(\varLambda = E_{\varLambda }/\epsilon \), where \(m_0\) and \(E_{\varLambda }\) are positive constants, so that the particle’s de Broglie wavelength and the largest energy scale of the bath are fixed as \(\epsilon \rightarrow 0\). We study the limit as \(\epsilon \rightarrow 0\) of the rescaled model and derive a limiting equation for the (slow) particle’s position variable. We find that the limiting equation contains several drift correction terms, the quantum noise-induced drifts, including terms of purely quantum nature, with no classical counterparts.     

Stopping of Heavy Ions in Magnetized Strongly Coupled Plasmas: High‐Velocity Limit

The energy loss of a heavy ion moving in a magnetized strongly coupled electron plasma is considered within the linear response treatment and in high‐velocity regime. The analytical expressions for the stopping power have been found for the arbitrary ion incidence angle. The obtained general expression for the stopping power is analyzed for the ion which moves parallel or perpendicular to the magnetic field. It is found that in general the magnetic field and the Coulomb coupling reduce the stopping power as well as the dynamical screening length at high velocities. The influence of the magnetic field and the Coulomb coupling on the high‐velocity stopping power is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Hierarchy Principle and the Large Mass Limit of the Linear Sigma Model

In perturbation theory we study the matching in four dimensions between the linear sigma model in the large mass limit and the renormalized nonlinear sigma model in the recently proposed flat connection formalism. We consider both the chiral limit and the strong coupling limit of the linear sigma model. Our formalism extends to Green functions with an arbitrary number of pion legs, at one loop level, on the basis of the hierarchy as an efficient unifying principle that governs both limits. While the chiral limit is straightforward, the matching in the strong coupling limit requires careful use of the normalization conditions of the linear theory, in order to exploit the functional equation and the complete set of local solutions of its linearized form.     

Rest mass of shears and cracks

Plastic shears and tensile cracks are accompanied by mass transfer that allows the rest mass to be assigned to them. The developed concepts allow dynamic problems to be solved when the process rates are such that inertia forces are comparable with the shear resistance forces. The feasibility is demonstrated of elastic field expression as a sum of two independent stress fields, with the first field caused by a nonuniform mass density distribution and the second purely shear field. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 69–78, January, 2006.     

Rest frames for tachyons and photons

A formalism is developed which admits particles faster than light and reference frames faster than light and as fast as light. It is fully consistent with the physical principles of special relativity. The necessity of introducing imaginary quantities does not arise. It does not encounter any difficulties with the principle of causality if it is reasonably interpreted.Dedicated to Prof. E. C. G. Sudarshan, in honor of his receipt of the Padmabushan Award.     

On the Zero Mass Limit of Tagged Particle Diffusion in the 1-d Rayleigh-Gas

We consider the M→0 limit for tagged particle diffusion in a 1-dimensional Rayleigh-gas, studied originaly by Sinai and Soloveichik [Ya. G. Sinai, M. R. Soloveichik, Commun. Math. Phys. 104:423–443 (1986)], and by Szász and Tóth [D. Szász, B. Tóth, Commun. Math. Phys. 104:445–457 (1986)], respectively. In this limit we derive a new type of model for tagged particle diffusion, for which the two central particles, in addition to elastic collisions with the rest of the gas, interact with Calogero-Moser-Sutherland (i.e. inverse quadratic) potential. Computer simulations on this new model reproduce exactly the numerical value of the limiting variance obtained by Boldrighini, Frigio and Tognetti in [C. Boldrighini, S. Frigio, D. Tognetti, J. Stat. Phys. 108:703–712 (2002)]. Dedicated to Domokos Szász on his 65th birthday.     

Cooper对质心定向运动速度的研究

研究了稳恒超导电流密度 j=ensνs中 ,νS在产生磁场方面的作用 ;指出超导抗磁性起源的物理本质是 ,νSC(T)很大 (约为 1 0 3 - 1 0 4 ms- 1) ,νSC(0 )的上限是 0 K时电子 Fermi速度 (数量级为1 0 5ms- 1) ;并说明了 London穿透深度的物理意义。指出 L ondon穿透深度是产生拆对磁场 Hc(T)所要求的 Jc(T)分布的最小线度。     

The Low Energy Limit of String Theory and its Compactifications with Background Fluxes

String theory is consistently defined in ten dimensions. In order to extract any information about four-dimensional physics, we need to understand the properties of the six-dimensional compact manifold orthogonal to our four-dimensional universe. A possibility that is being very much explored lately is to look at manifolds on which background fluxes are turned on. In this article, we present an introduction to string theory, focusing on its massless sector. We then review traditional compactifications to four–dimensions, and finally motivate and describe the so-called flux compactifications. We interpret the allowed six-dimensional manifolds from the point of view of generalized complex geometry.     

On the Boyd-Kadomstev System for a Three-Wave Coupling Problem and its Asymptotic Limit

We consider the Boyd-Kadomstev system which is in particular a model for the Brillouin backscattering in laser-plasma interaction. It couples the propagation of two laser beams, the incoming and the backscattered waves, with an ion acoustic wave which propagates at a much slower speed. The ratio ${\varepsilon}$ between the plasma sound velocity and the (group) velocity of light is small, with typical value of order 10^?3. In this paper, we make a rigorous analysis of the behavior of solutions as ${\varepsilon \to 0}$ . This problem can be cast in the general framework of fast singular limits for hyperbolic systems. The main new point which is addressed in our analysis is that the singular relaxation term present in the equation is a nonlinear first order system.     

Mass Transfer Induced by a Wave Perturbation on the Surface of the Velocity Field Tangential Discontinuity

An analytical asymptotic model of relative mass transfer in a system of two ideal immiscible unmixed liquids with a capillary gravitational periodic wave propagating over the interface has been constructed.