Quantum corrections to the mass of the supersymmetric vortex

We calculate quantum corrections to the mass of the vortex in N=2 supersymmetric abelian Higgs model in (2+1) dimensions. We put the system in a box and apply the zeta function regularization. The boundary conditions inevitably violate a part of the supersymmetries. Remaining supersymmetry is however enough to ensure isospectrality of relevant operators in bosonic and fermionic sectors. A non-zero correction to the mass of the vortex comes from finite renormalization of couplings.Comment: Latex, 18 pp; v2 reference added; v3 minor change

Conformal geometry of the supercotangent and spinor bundles

We study the actions of local conformal vector fields X∈conf(M,g) on the spinor bundle of (M,g) and on its classical counterpart: the supercotangent bundle M of (M,g). We first deal with the classical framework and determine the Hamiltonian lift of conf(M,g) to M. We then perform the geometric quantization of the supercotangent bundle of (M,g), which constructs the spinor bundle as the quantum representation space. The Kosmann Lie derivative of spinors is btained by quantization of the comoment map. The quantum and classical actions of conf(M,g) turn, respectively, the space of differential operators acting on spinor densities and the space of their symbols into conf(M,g)-modules. They are filtered and admit a common associated graded module. In the conformally flat case, the latter helps us determine the conformal invariants of both conf(M,g)-modules, in particular the conformally odd powers of the Dirac operator.Peer reviewe

Chaos in a double driven dissipative nonlinear oscillator

We propose an anharmonic oscillator driven by two periodic forces of different frequencies as a new time-dependent model for investigating quantum dissipative chaos. Our analysis is done in the frame of statistical ensemble of quantum trajectories in quantum state diffusion approach. Quantum dynamical manifestation of chaotic behavior, including the emergence of chaos, properties of strange attractors, and quantum entanglement are studied by numerical simulation of ensemble averaged Wigner function and von Neumann entropy.Comment: 9 pages, 18 figure

Analyses of a novel SCN5A mutation (C1850S): conduction vs. repolarization disorder hypotheses in the Brugada syndrome.

AIMS: Brugada syndrome (BrS) is characterized by arrhythmias leading to sudden cardiac death. BrS is caused, in part, by mutations in the SCN5A gene, which encodes the sodium channel alpha-subunit Na(v)1.5. Here, we aimed to characterize the biophysical properties and consequences of a novel BrS SCN5A mutation. METHODS AND RESULTS: SCN5A was screened for mutations in a male patient with type-1 BrS pattern ECG. Wild-type (WT) and mutant Na(v)1.5 channels were expressed in HEK293 cells. Sodium currents (I(Na)) were analysed using the whole-cell patch-clamp technique at 37 degrees C. The electrophysiological effects of the mutation were simulated using the Luo-Rudy model, into which the transient outward current (I(to)) was incorporated. A new mutation (C1850S) was identified in the Na(v)1.5 C-terminal domain. In HEK293 cells, mutant I(Na) density was decreased by 62% at -20 mV. Inactivation of mutant I(Na) was accelerated in a voltage-dependent manner and the steady-state inactivation curve was shifted by 11.6 mV towards negative potentials. No change was observed regarding activation characteristics. Altogether, these biophysical alterations decreased the availability of I(Na). In the simulations, the I(to) density necessary to precipitate repolarization differed minimally between the two genotypes. In contrast, the mutation greatly affected conduction across a structural heterogeneity and precipitated conduction block. CONCLUSION: Our data confirm that mutations of the C-terminal domain of Na(v)1.5 alter the inactivation of the channel and support the notion that conduction alterations may play a significant role in the pathogenesis of BrS

From Coherent Modes to Turbulence and Granulation of Trapped Gases

The process of exciting the gas of trapped bosons from an equilibrium initial state to strongly nonequilibrium states is described as a procedure of symmetry restoration caused by external perturbations. Initially, the trapped gas is cooled down to such low temperatures, when practically all atoms are in Bose-Einstein condensed state, which implies the broken global gauge symmetry. Excitations are realized either by imposing external alternating fields, modulating the trapping potential and shaking the cloud of trapped atoms, or it can be done by varying atomic interactions by means of Feshbach resonance techniques. Gradually increasing the amount of energy pumped into the system, which is realized either by strengthening the modulation amplitude or by increasing the excitation time, produces a series of nonequilibrium states, with the growing fraction of atoms for which the gauge symmetry is restored. In this way, the initial equilibrium system, with the broken gauge symmetry and all atoms condensed, can be excited to the state, where all atoms are in the normal state, with completely restored gauge symmetry. In this process, the system, starting from the regular superfluid state, passes through the states of vortex superfluid, turbulent superfluid, heterophase granular fluid, to the state of normal chaotic fluid in turbulent regime. Both theoretical and experimental studies are presented.Comment: Latex file, 25 pages, 4 figure

Dialectics and difference: against Harvey's dialectical post-Marxism

David Harvey`s recent book, Justice, nature and the geography of difference (JNGD), engages with a central philosophical debate that continues to dominate human geography: the tension between the radical Marxist project of recent decades and the apparently disempowering relativism and `play of difference' of postmodern thought. In this book, Harvey continues to argue for a revised `post-Marxist' approach in human geography which remains based on Hegelian-Marxian principles of dialectical thought. This article develops a critique of that stance, drawing on the work of Jacques Derrida, Gilles Deleuze and Felix Guattari. I argue that dialectical thinking, as well as Harvey's version of `post-Marxism', has been undermined by the wide-ranging `post-' critique. I suggest that Harvey has failed to appreciate the full force of this critique and the implications it has for `post-Marxist' ontology and epistemology. I argue that `post-Marxism', along with much contemporary human geography, is constrained by an inflexible ontology which excessively prioritizes space in the theory produced, and which implements inflexible concepts. Instead, using the insights of several `post-' writers, I contend there is a need to develop an ontology of `context' leading to the production of `contextual theories'. Such theories utilize flexible concepts in a multilayered understanding of ontology and epistemology. I compare how an approach which produces a `contextual theory' might lead to more politically empowering theory than `post-Marxism' with reference to one of Harvey's case studies in JNGD

A measurement of the tau mass and the first CPT test with tau leptons

We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV using tau pairs from Z0 decays. To test CPT invariance we compare the masses of the positively and negatively charged tau leptons. The relative mass difference is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.

Measurement of the B0 Lifetime and Oscillation Frequency using B0->D*+l-v decays

The lifetime and oscillation frequency of the B0 meson has been measured using B0->D*+l-v decays recorded on the Z0 peak with the OPAL detector at LEP. The D*+ -> D0pi+ decays were reconstructed using an inclusive technique and the production flavour of the B0 mesons was determined using a combination of tags from the rest of the event. The results t_B0 = 1.541 +- 0.028 +- 0.023 ps, Dm_d = 0.497 +- 0.024 +- 0.025 ps-1 were obtained, where in each case the first error is statistical and the second systematic.Comment: 17 pages, 4 figures, submitted to Phys. Lett.

Search for Higgs Bosons in e+e- Collisions at 183 GeV

The data collected by the OPAL experiment at sqrts=183 GeV were used to search for Higgs bosons which are predicted by the Standard Model and various extensions, such as general models with two Higgs field doublets and the Minimal Supersymmetric Standard Model (MSSM). The data correspond to an integrated luminosity of approximately 54pb-1. None of the searches for neutral and charged Higgs bosons have revealed an excess of events beyond the expected background. This negative outcome, in combination with similar results from searches at lower energies, leads to new limits for the Higgs boson masses and other model parameters. In particular, the 95% confidence level lower limit for the mass of the Standard Model Higgs boson is 88.3 GeV. Charged Higgs bosons can be excluded for masses up to 59.5 GeV. In the MSSM, mh > 70.5 GeV and mA > 72.0 GeV are obtained for tan{beta}>1, no and maximal scalar top mixing and soft SUSY-breaking masses of 1 TeV. The range 0.8 < tanb < 1.9 is excluded for minimal scalar top mixing and m{top} < 175 GeV. More general scans of the MSSM parameter space are also considered.Comment: 49 pages. LaTeX, including 33 eps figures, submitted to European Physical Journal