Maxwell-Chern-Simons Q-balls

We examine the energetics of $Q$-balls in Maxwell-Chern-Simons theory in two space dimensions. Whereas gauged $Q$-balls are unallowed in this dimension in the absence of a Chern-Simons term due to a divergent electromagnetic energy, the addition of a Chern-Simons term introduces a gauge field mass and renders finite the otherwise-divergent electromagnetic energy of the $Q$-ball. Similar to the case of gauged $Q$-balls, Maxwell-Chern-Simons $Q$-balls have a maximal charge. The properties of these solitons are studied as a function of the parameters of the model considered, using a numerical technique known as relaxation. The results are compared to expectations based on qualitative arguments.Comment: 6 pages. Talk given at Theory CANADA 2, Perimeter Institut

Anisotropy in the Antiferromagnetic Spin Fluctuations of Sr2RuO4

It has been proposed that Sr_2RuO_4 exhibits spin triplet superconductivity mediated by ferromagnetic fluctuations. So far neutron scattering experiments have failed to detect any clear evidence of ferromagnetic spin fluctuations but, instead, this type of experiments has been successful in confirming the existence of incommensurate spin fluctuations near q=(1/3 1/3 0). For this reason there have been many efforts to associate the contributions of such incommensurate fluctuations to the mechanism of its superconductivity. Our unpolarized inelastic neutron scattering measurements revealed that these incommensurate spin fluctuations possess c-axis anisotropy with an anisotropic factor \chi''_{c}/\chi''_{a,b} of \sim 2.8. This result is consistent with some theoretical ideas that the incommensurate spin fluctuations with a c-axis anisotropy can be a origin of p-wave superconductivity of this material.Comment: 5 pages, 3 figures; accepted for publication in PR

Cyclotron Resonance in the Layered Perovskite Superconductor Sr2RuO4

We have measured the cyclotron masses in Sr2RuO4 through the observation of periodic-orbit-resonances - a magnetic resonance technique closely related to cyclotron resonance. We obtain values for the alpha, beta and gamma Fermi surfaces of (4.33+/-0.05)me, (5.81+/-0.03)me and (9.71+/-0.11)me respectively. The appreciable differences between these results and those obtained from de Haas- van Alphen measurements are attributable to strong electron-electron interactions in this system. Our findings appear to be consistent with predictions for a strongly interacting Fermi liquid; indeed, semi-quantitative agreement is obtained for the electron pockets beta and gamma.Comment: 4 pages + 3 figure

Scaling Study of the Leptonic Decay Constants of Heavy-Light Mesons: A Consumers Report on Improvement Factors

A high statistics calculation, performed at $\beta =5.74,\;6.00$ and $6.26$, enables us to study the variation of the leptonic decay constants $f_P$ of heavy pseudoscalar mesons with the lattice spacing $a$. We observe only a weak $a$ dependence when the standard $\sqrt{2\kappa}$ normalization is used for the quark fields, whereas application of the Kronfeld-Mackenzie normalization induces a stronger variation with $a$. Increasing the meson mass from $1.1GeV$ to $2.3GeV$ this situation becomes even more pronounced.Comment: Lattice 93, 3 pages Latex, 2 postscript figures (epsf style

Cohomology of skew-holomorphic Lie algebroids

We introduce the notion of skew-holomorphic Lie algebroid on a complex manifold, and explore some cohomologies theories that one can associate to it. Examples are given in terms of holomorphic Poisson structures of various sorts.Comment: 16 pages. v2: Final version to be published in Theor. Math. Phys. (incorporates only very minor changes

Field theoretic description of the abelian and non-abelian Josephson effect

We formulate the Josephson effect in a field theoretic language which affords a straightforward generalization to the non-abelian case. Our formalism interprets Josephson tunneling as the excitation of pseudo-Goldstone bosons. We demonstrate the formalism through the consideration of a single junction separating two regions with a purely non-abelian order parameter and a sandwich of three regions where the central region is in a distinct phase. Applications to various non-abelian symmetry breaking systems in particle and condensed matter physics are given.Comment: 10 pages no figure

Jacobi structures revisited

Jacobi algebroids, that is graded Lie brackets on the Grassmann algebra associated with a vector bundle which satisfy a property similar to that of the Jacobi brackets, are introduced. They turn out to be equivalent to generalized Lie algebroids in the sense of Iglesias and Marrero and can be viewed also as odd Jacobi brackets on the supermanifolds associated with the vector bundles. Jacobi bialgebroids are defined in the same manner. A lifting procedure of elements of this Grassmann algebra to multivector fields on the total space of the vector bundle which preserves the corresponding brackets is developed. This gives the possibility of associating canonically a Lie algebroid with any local Lie algebra in the sense of Kirillov.Comment: 20 page

f_K/f_pi in Full QCD with Domain Wall Valence Quarks

We compute the ratio of pseudoscalar decay constants f_K/f_pi using domain-wall valence quarks and rooted improved Kogut-Susskind sea quarks. By employing continuum chiral perturbation theory, we extract the Gasser-Leutwyler low-energy constant L_5, and extrapolate f_K/f_pi to the physical point. We find: f_K/f_pi = 1.218 (+- 0.002) (+0.011 -0.024) where the first error is statistical and the second error is an estimate of the systematic due to chiral extrapolation and fitting procedures. This value agrees within the uncertainties with the determination by the MILC collaboration, calculated using Kogut-Susskind valence quarks, indicating that systematic errors arising from the choice of lattice valence quark are small.Comment: 14 pages, 9 figure

Statistical Performance Analysis of an Ant-Colony Optimisation Application in S-NET

Kenneth MacKenzie, Philip K. F. Hölzenspies, Kevin Hammond, Raimund Kirner, Vu Thien Nga Nguyen, Iraneus te Boekhorst, Clemens Grelck, Raphael Poss, Merijn Verstraaten, 'Statistical Performance Analysis of an Ant-Colony Optimisation Application in S-NET'. Paper presented at the 2nd Workshop on Feedback-Directed Compiler Optimization for Multi-Core Architectures. Berlin, Germany, 12 January 2013.We consider an ant-colony optimsation problem implemented on a multicore system as a collection of asynchronous stream- processing components under the control of the S-NET coordina- tion language. Statistical analysis and visualisation techniques are used to study the behaviour of the application, and this enables us to discover and correct problems in both the application program and the run-time system underlying S-NET