Baryon kinetic energy loss in the color flux tube model

This article generalizes Schwinger's mechanism for particles production in the arbitrary finite field volume. McLerran-Venugopolan(MV) model and iterative solution of DGLAP equation in the double leading log approximation for small x gluon distribution function were used to derive the new formula for initial chromofield energy density. This initial chromofield energy is distributed among color neutral clusters or strings of different length. This strings are stretched by receding nucleus. From the proposed mechanism of string fragmentation or color field decay based on exact solution of Dirac equation in the different finite volume, the new formulae for esimated baryon kinetic energy loss and rapidity spectrum of produced partons were derived.Comment: 13 pages, 2 figure

WLC22-4: Efficient request mechanism usage in IEEE 802.16

IEEE 802.16 protocols for metropolitan broadband wireless access systems have been standardized recently. According to the standard, a subscriber station can deliver bandwidth request messages to a base station by numerous methods. This paper provides both the simulation and analytical models for the investigation of specified random access method, which is compared with centralized polling and station- grouping mechanisms. Based on the assumptions of Bernoulli request arrival process and ideal channel conditions, the mean delay of a request transmission is evaluated for varying number of transmission opportunities and different arrival rates

Use of dynamical coupling for improved quantum state transfer

We propose a method to improve quantum state transfer in transmission lines. The idea is to localize the information on the last qubit of a transmission line, by dynamically varying the coupling constants between the first and the last pair of qubits. The fidelity of state transfer is higher then in a chain with fixed coupling constants. The effect is stable against small fluctuations in the system parameters.Comment: 5 pages, 7 figure

Role of interference in quantum state transfer through spin chains

We examine the role that interference plays in quantum state transfer through several types of finite spin chains, including chains with isotropic Heisenberg interaction between nearest neighbors, chains with reduced coupling constants to the spins at the end of the chain, and chains with anisotropic coupling constants. We evaluate quantitatively both the interference corresponding to the propagation of the entire chain, and the interference in the effective propagation of the first and last spins only, treating the rest of the chain as black box. We show that perfect quantum state transfer is possible without quantum interference, and provide evidence that the spin chains examined realize interference-free quantum state transfer to a good approximation.Comment: 10 figure

Exotic behavior and crystal structures of calcium under pressure

Experimental studies established that calcium undergoes several counterintuitive transitions under pressure: fcc \rightarrow bcc \rightarrow simple cubic \rightarrow Ca-IV \rightarrow Ca-V, and becomes a good superconductor in the simple cubic and higher-pressure phases. Here, using ab initio evolutionary simulations, we explore the behavior of Ca under pressure and find a number of new phases. Our structural sequence differs from the traditional picture for Ca, but is similar to that for Sr. The {\beta}-tin (I41/amd) structure, rather than simple cubic, is predicted to be the theoretical ground state at 0 K and 33-71 GPa. This structure can be represented as a large distortion of the simple cubic structure, just as the higher-pressure phases stable between 71 and 134 GPa. The structure of Ca-V, stable above 134 GPa, is a complex host-guest structure. According to our calculations, the predicted phases are superconductors with Tc increasing under pressure and reaching ~20 K at 120 GPa, in good agreement with experiment

Baryon deceleration by strong chromofields in ultrarelativistic nuclear collisions

It is assumed that strong chromofields are generated at early stages of ultrarelativistic heavy-ion collisions which give rise to a collective deceleration of net baryons from colliding nuclei. We have solved classical equations of motion for baryonic slabs under the action of a time-dependent longitudinal chromoelectric field. It is demonstrated that the slab final rapidities are rather sensitive to the strength and decay time of the chromofield as well as to the back reaction of the produced partonic plasma. The net-baryon rapidity loss of about 2 units, found for most central Au-Au collisions at RHIC, can be explained by the action of chromofields with the initial energy density of about 50 GeV/fm^3. Predictions for the baryon stopping at the LHC are made.Comment: 10 pages in revtex, 3 eps figure

Lie Symmetry Analysis for Cosserat Rods

We consider a subsystem of the Special Cosserat Theory of Rods and construct an explicit form of its solution that depends on three arbitrary functions in (s,t) and three arbitrary functions in t. Assuming analyticity of the arbitrary functions in a domain under consideration, we prove that the obtained solution is analytic and general. The Special Cosserat Theory of Rods describes the dynamic equilibrium of 1-dimensional continua, i.e. slender structures like fibers, by means of a system of partial differential equations.Comment: 12 Pages, 1 Figur

Quantum state transfer in arrays of flux qubits

In this work, we describe a possible experimental realization of Bose's idea to use spin chains for short distance quantum communication [S. Bose, {\it Phys. Rev. Lett.} {\bf 91} 207901]. Josephson arrays have been proposed and analyzed as transmission channels for systems of superconducting charge qubits. Here, we consider a chain of persistent current qubits, that is appropriate for state transfer with high fidelity in systems containing flux qubits. We calculate the fidelity of state transfer for this system. In general, the Hamiltonian of this system is not of XXZ-type, and we analyze the magnitude and the effect of the terms that don't conserve the z-component of the total spin.Comment: 10 pages, 8 figure

Photometric and radar observations of an excited eruption in the Zarnitsa-2 experiment

In a controlled experiment a ground photometer and radar station recorded an increase in night sky luminescence following injection of an electron beam into the atmosphere from a rocket at altitudes 80 to 154 km. A main and supplementary scattering and luminescene regions were observed. The effect is presumed to be due to electron eruption induced by artificial action on the magnetosphere

Some Features of Boron Isotopes Separation by Laser-Assisted Retardation of Condensation Method

Boron isotopes have many applications in industry: medicine, semiconductor, and solar energy. Especially massive demand is for boron-10 isotopes in nuclear industry for nuclear reactors shielding and control. Various aspects of laser-assisted boron isotope separation by retardation of condensation method, such as irradiation conditions and laser and vacuum system design, have been considered. Irradiation conditions include interaction scheme of laser radiation and supersonic beam, dependence of efficiency of excitation on gas flow temperature and pressure. Basic physical constraints on laser intensity and its spectral properties have been discussed. The relation of gas flow properties, nozzle design, and vacuuming rate has been elucidated as well