Anomaly cancellation for anisotropic lattice fields with extra dimensions

The current flow from the bulk is due to the anomaly on the brane-but the absence of current flow is not, necessarily, due to anomaly cancellation, but to the absence of the chiral zero modes themselves, due to the existence of the layered phase. This can be understood in terms of the difference between the Chern-Simons terms in three and five dimensions. Thus the anomaly cancellation in four dimensions, which is essential for shielding the boundary from quantum effects within the bulk, makes sense only along the transition line between the layered and the Coulomb phase, which, in turn, requires the presence of a compact U(1) factor for the gauge group.Comment: 6 pages, 4 figures, LaTeX2e, uses PoS. Contribution to The XXVII International Symposium on Lattice Field Theory - LAT2009, July 26-31 2009,Peking University, Beijing, Chin

A Process Model of Locational Change in Entrepreneurial Firms: An Evolutionary Perspective

How do changes in the spatial organization of entrepreneurial firms come about? This paper provides a conceptualisation of the process of locational change. A process model of locational change is constructed on the basis of an empirical study of 109 locational events during the life course of 25 young firms in knowledge intensive sectors (knowledge services and biomedicals). This process model of locational change maps both internal and external variation and selection processes. This model contributes to the development of a causal process theory of the spatial development of (new) firms.Location;Decision-Making;Entrepreneurial Firms;Evolutionary Theory;Process Models

A Process Model of Locational Change in Entrepreneurial Firms: An Evolutionary Perspective

How do changes in the spatial organization of entrepreneurial firms come about? This paper provides a conceptualisation of the process of locational change. A process model of locational change is constructed on the basis of an empirical study of 109 locational events during the life course of 25 young firms in knowledge intensive sectors (knowledge services and biomedicals). This process model of locational change maps both internal and external variation and selection processes. This model contributes to the development of a causal process theory of the spatial development of (new) firms.location, entrepreneurial firms, evolutionary theory, decision-making, process models

Circular polarization signals of cloudy (exo)planets

The circular polarization of light that planets reflect is often neglected because it is very small compared to the linear polarization. It could, however, provide information on a planet's atmosphere and surface, and on the presence of life, because homochiral molecules that are the building blocks of life on Earth are known to reflect circularly polarized light. We compute $P_c$, the degree of circular polarization, for light that is reflected by rocky (exo)planets with liquid water or sulfuric acid solution clouds, both spatially resolved across the planetary disk and, for planets with patchy clouds, integrated across the planetary disk, for various planetary phase angles $\alpha$. The optical thickness and vertical distribution of the atmospheric gas and clouds, the size parameter and refractive index of the cloud particles, and $\alpha$ all influence $P_c$. Spatially resolved, $P_c$ varies between $\pm 0.20\%$ (the sign indicates the polarization direction). Only for small gas optical thicknesses above the clouds do significant sign changes (related to cloud particle properties) across the planets' hemispheres occur. For patchy clouds, the disk--integrated $P_c$ is typically smaller than $\pm 0.025\%$, with maximums for $\alpha$ between $40^\circ$ and $70^\circ$, and $120^\circ$ to $140^\circ$. As expected, the disk--integrated $P_c$ is virtually zero at $\alpha=0^\circ$ and 180$^\circ$. The disk--integrated $P_c$ is also very small at $\alpha \approx 100^\circ$. Measuring circular polarization signals appears to be challenging with current technology. The small atmospheric circular polarization signal could, however, allow the detection of circular polarization due to homochiral molecules. Confirmation of the detectability of such signals requires better knowledge of the strength of circular polarization signals of biological sources.Comment: 15 pages, 11 figures, Accepted for publication in Astronomy and Astrophysic

Unconstrained Variables and Equivalence Relations for Lattice Gauge Theories

We write the partition function for a lattice gauge theory, with compact gauge group, exactly in terms of unconstrained variables and show that, in the mean field approximation, the dynamics of pure gauge theories, invariant under compact, continuous,groups of rank 1 is the same for all. We explicitly obtain the equivalence for the case of SU(2) and U(1) and show that it obtains, also, if we consider saddle point configurations that are not,necessarily, uniform, but only proportional to the identity for both groups. This implies that the phase diagrams of the (an)isotropic SU(2) theory and the (an)isotropic U(1) theory in any dimension are identical, within this approximation, up to a re-evaluation of the numerical values of the coupling constants at the transitions. Only nonuniform field configurations, that, also, belong to higher dimensional representations for Yang--Mills fields, will be able to p robe the difference between them. We also show under what conditions the global symmetry of an anisotropic term in the lattice action can be promoted to a gauge symmetry of the theory on layers and point out how deconstruction and flux compactification scenaria may thus be studied on the lattice.Comment: 14 pages, LateX2e. Expanded presentation of equivalence relation. Added discussion on how the global symmetry of the anisotropic term can be promoted to a gauge symmetry on a laye

Second Order Phase Transition in Anisotropic Lattice Gauge Theories with Extra Dimensions

Field theories with extra dimensions live in a limbo. While their classical solutions have been the subject of considerable study, their quantum aspects are difficult to control. A special class of such theories are anisotropic gauge theories. The anisotropy was originally introduced to localize chiral fermions. Their continuum limit is of practical interest and it will be shown that the anisotropy of the gauge couplings plays a crucial role in opening the phase diagram of the theory to a new phase, that is separated from the others by a second order phase transition. The mechanism behind this is generic for a certain class of models, that can be studied with lattice techniques. This leads to new perspectives for the study of quantum effects of extra dimensions.Comment: 7 pages, 1 figure. Uses PoS.cls. Contribution to The XXVIII International Symposium on Lattice Filed Theory, June 14-19,2010,Villasimius, Sardinia Ital

Chaotic Information Processing by Extremal Black Holes

We review an explicit regularization of the AdS$_2$/CFT$_1$ correspondence, that preserves all isometries of bulk and boundary degrees of freedom. This scheme is useful to characterize the space of the unitary evolution operators that describe the dynamics of the microstates of extremal black holes in four spacetime dimensions. Using techniques from algebraic number theory to evaluate the transition amplitudes, we remark that the regularization scheme expresses the fast quantum computation capability of black holes as well as its chaotic nature.Comment: 8 pages, 2 JPEG figues. Contribution to the VII Black Holes Workshop, Aveiro PT, Decemeber 201