Classical String Solutions in Effective Infrared Theory of SU(3) Gluodynamics

We investigate string solutions to the classical equations of motion ("classical QCD strings") for a dual Ginzburg-Landau model corresponding to SU(3) gluodynamics in an abelian projection. For a certain relation between couplings of the model the string solutions are defined by first order differential equations. These solutions are related to vortex configurations of the Abelian Higgs model in the Bogomol'ny limit. An analytic expression for the string tension is derived and the string-string interactions are discussed. Our results imply that the vacuum of SU(3) gluodynamics is near a border between type-I and type-II dual superconductivity.Comment: 7 pages, LaTeX2e; v2: references added and typos correcte

Disruption management in passenger railway transportation.

This paper deals with disruption management in passengerrailway transportation. In the disruption management process, manyactors belonging to different organizations play a role. In this paperwe therefore describe the process itself and the roles of thedifferent actors.Furthermore, we discuss the three main subproblems in railwaydisruption management: timetable adjustment, and rolling stock andcrew re-scheduling. Next to a general description of these problems,we give an overview of the existing literature and we present somedetails of the specific situations at DSB S-tog and NS. These arethe railway operators in the suburban area of Copenhagen, Denmark,and on the main railway lines in the Netherlands, respectively.Since not much research has been carried out yet on OperationsResearch models for disruption management in the railway context,models and techniques that have been developed for related problemsin the airline world are discussed as well.Finally, we address the integration of the re-scheduling processesof the timetable, and the resources rolling stock and crew.

Aharonov-Bohm effect, Center Monopoles and Center Vortices in SU(2) Lattice Gluodynamics

SU(2) gluodynamics is investigated numerically and analytically in the (Indirect) Maximal Center gauge at finite temperature. The center vortices are shown to be condensed in the confinement phase and dilute in the deconfinement phase. A new physical object, center monopole, is constructed. We show that the center monopole condensate is the order parameter of deconfinement phase transition. The linking of the vortex worldsheets and quark trajectories is identified with the Aharonov-Bohm interaction in an effective Abelian Higgs theory. We conclude that the confinement in the Maximal Center gauge can be explained by a new mechanism called "the real superconductor mechanism".Comment: LATTICE98(confine), 3 pages, LaTeX, 2 eps figures, uses espcrc2.st

Negotiating safety practice in small construction companies

AbstractSmall construction companies have high rates of work related injuries and pervasive challenges in preventing them. This article examines safety practice from the employee perspective, taking into account the role of the owner–manager and interactions with customers in everyday work settings. Data were derived from a qualitative multi-case study of ten small construction companies (carpentry/plumbing/masonry) involving one or two-man work crews. The analytic approach is phenomenological, based on thematic content analysis of interviews and participant-observations. The employees’ general approach to safety was “to take care of oneself”, which, in addition to standardized rule-based knowledge, drew on individual feelings, personal experience and the balancing of various concerns in different work settings, e.g. workflow, customer satisfaction, good work relations and safety issues. In the context of small companies, safety practice was negotiated in the tension between owner–manager decisions and employees’ self-administration, which also was reflected in the way safety was communicated and learned within the companies as a matter of professionalism and individual mastering. Safety was rarely in explicit focus among employees in the small construction companies. It was an intrinsic part of their craftsmanship, established and negotiated in work situations and in interactions, in particular with customers. Safety issues were rarely shared or communicated as a common issue within the company. Consequently owner–managers had limited impact on the employees’ daily safety practices. Injury prevention approaches should take into account the limited impact that owner–managers had on the day-to-day safety practices, as well as the importance of the employees’ relationships with the customers

Aharonov--Bohm Effect in 3D Abelian Higgs Theory

We study a field--theoretical analogue of the Aharonov--Bohm effect in the 3D Abelian Higgs Model: the corresponding topological interaction is proportional to the linking number of the vortex and the particle world trajectories. We show that the Aharonov--Bohm effect gives rise to a nontrivial interaction of tested charged particles.Comment: LaTeX, 3 pages, 1 figure, uses epsf.sty; talk presented at LATTICE96(topology), St. Louis, US

Vortex profiles and vortex interactions at the electroweak crossover

Local correlations of Z-vortex operators with gauge and Higgs fields (lattice quantum vortex profiles) as well as vortex two-point functions are studied in the crossover region near a Higgs mass of 100 GeV within the 3D SU(2) Higgs model. The vortex profiles resemble certain features of the classical vortex solutions in the continuum. The vortex-vortex interactions are analogous to the interactions of Abrikosov vortices in a type-I superconductor.Comment: talk at LATTICE99(electroweak), 3 pages and 5 EPS figure

Experimental evidence of a change of exchange anisotropy sign with temperature in Zn-substituted Cu2OSeO3

We report small-angle neutron scattering from the conical state in a single crystal of Zn-substituted Cu 2 OSeO 3 . Using a 3D vector-field magnet to reorient the conical wave vector, our measurements show that the magnitude of the conical wave vector changes as a function of crystallographic direction. These changes are explained using the anisotropic exchange interaction (AEI) within the continuum model, whose magnitude in free-energy transitions from a maxima to a minima along the ⟨ 111 ⟩ and ⟨ 100 ⟩ crystallographic directions respectively. We further find that the AEI free-energy constant undergoes a change of sign from positive to negative with decreasing temperature. Unlike in the related compound FeGe, where similar behavior of the AEI induces a reorientation of the helical wave vector, we show that the zero field helical wave vector in ( Cu 0.98 Zn 0.02 ) 2 OSeO 3 remains along the ⟨ 100 ⟩ directions at all temperatures due to the competing fourth-order magnetocrystalline anisotropy becoming dominant at lower temperatures

Electromagnetic superconductivity of vacuum induced by strong magnetic field

The quantum vacuum may become an electromagnetic superconductor in the presence of a strong external magnetic field of the order of 10^{16} Tesla. The magnetic field of the required strength (and even stronger) is expected to be generated for a short time in ultraperipheral collisions of heavy ions at the Large Hadron Collider. The superconducting properties of the new phase appear as a result of a magnetic-field-assisted condensation of quark-antiquark pairs with quantum numbers of electrically charged rho mesons. We discuss similarities and differences between the suggested superconducting state of the quantum vacuum, a conventional superconductivity and the Schwinger pair creation. We argue qualitatively and quantitatively why the superconducting state should be a natural ground state of the vacuum at the sufficiently strong magnetic field. We demonstrate the existence of the superconducting phase using both the Nambu-Jona-Lasinio model and an effective bosonic model based on the vector meson dominance (the rho-meson electrodynamics). We discuss various properties of the new phase such as absence of the Meissner effect, anisotropy of superconductivity, spatial inhomogeneity of ground state, emergence of a neutral superfluid component in the ground state and presence of new topological vortices in the quark-antiquark condensates.Comment: 37 pages, 14 figures, to appear in Lect. Notes Phys. "Strongly interacting matter in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Ye

Monopole Chains in the Compact Abelian Higgs Model with doubly-charged Matter Field

We study the properties of topological defects in the lattice compact Abelian Higgs Model with charge Q=2 matter field. We find that monopoles and antimonopoles form chain-like structures which are dense in the confinement/symmetric phase. In this phase the mentioned structures explain both the confinement of single-charged and the breaking of strings spanned between doubly-charged test particles. This observation helps to understand how the non-diagonal gluons, once taken into consideration in the Abelian projection of gluodynamics, could reproduce in this framework the string breaking for adjoint charges.Comment: 11 pages, 8 figures; Revision 1: two figures added, percolation properties discussed, title changed, enlarged version; Revision 2: misprints are corrected, to be published in Phys.Lett.

The Case for Quantum Key Distribution

Quantum key distribution (QKD) promises secure key agreement by using quantum mechanical systems. We argue that QKD will be an important part of future cryptographic infrastructures. It can provide long-term confidentiality for encrypted information without reliance on computational assumptions. Although QKD still requires authentication to prevent man-in-the-middle attacks, it can make use of either information-theoretically secure symmetric key authentication or computationally secure public key authentication: even when using public key authentication, we argue that QKD still offers stronger security than classical key agreement.Comment: 12 pages, 1 figure; to appear in proceedings of QuantumComm 2009 Workshop on Quantum and Classical Information Security; version 2 minor content revision