Differential Regularization of a Non-relativistic Anyon Model

Differential regularization is applied to a field theory of a non-relativistic charged boson field $\phi$ with $\lambda (\phi {}^{*} \phi)^2$ self-interaction and coupling to a statistics-changing $U(1)$ Chern-Simons gauge field. Renormalized configuration-space amplitudes for all diagrams contributing to the $\phi {}^{*} \phi {}^{*} \phi \phi$ 4-point function, which is the only primitively divergent Green's function, are obtained up to 3-loop order. The renormalization group equations are explicitly checked, and the scheme dependence of the $\beta$-function is investigated. If the renormalization scheme is fixed to agree with a previous 1-loop calculation, the 2- and 3-loop contributions to $\beta(\lambda,e)$ vanish, and $\beta(\lambda,e)$ itself vanishes when the ``self-dual'' condition relating $\lambda$ to the gauge coupling $e$ is imposed.Comment: 22 pages in ReVTEX (with a plaintext PostScript figure appended at end), MIT CTP #221

Current trends of accelerometry to assess physical activity

Evaluar la actividad física de forma precisa y fiable sigue siendo un importante reto para los epidemiólogos, científicos, médicos, especialistas en ejercicio e investigadores del comportamiento. Para ello, actualmente, los acelerómetros son dispositivos ampliamente utilizados en investigación científica. En el presente artículo se pretende dar muestra de cuál es la situación actual del uso de la acelerometría para cuantificar niveles de actividad física. Así como sus limitaciones y perspectivas de futuro con el fin de contribuir a su mejor uso

Titling and beyond: Evidence from Dar es Salaam, Tanzania

Land titling has been a policy priority for developing country cities for decades. In Sub-Saharan Africa and across the world, tenure formalization has been promoted as a tool to improve the quality and value of urban housing. The track record of these projects, however, has generally been disappointing. Why is this? In this paper, we argue that project design has paid too little attention to contextual features of land markets in estimating the benefits of formalization to individual households. We draw on evidence from a case study city – Dar es Salaam, Tanzania – to show that in cities where broader property rights institutions are incomplete and informal sources of tenure security are strong, formal property rights may not be valued by households. This raises questions about the households’ willingness to pay for regularisation and suggests that complementary strategies to build trust in government and consolidate public benefits of titling will be needed to ensure that projects have a beneficial impact

The Near-Horizon Limit of the Extreme Rotating d=5 Black Hole as a Homogenous Spacetime

We show that the spacetime of the near-horizon limit of the extreme rotating d=5 black hole, which is maximally supersymmetric in N=2,d=5 supergravity for any value of the rotation parameter j in [-1,1], is locally isomorphic to a homogeneous non-symmetric spacetime corresponding to an element of the 1-parameter family of coset spaces SO(2,1)x SO(3)/SO(2)_j in which the subgroup SO(2)_j is a combination of the two SO(2) subgroups of SO(2,1) and SO(3).Comment: Some points clarified and misprints corrected. Version to be published in Classical and Quantum Gravit

Bethe-Salpeter equation for doubly heavy baryons in the covariant instantaneous approximation

In the heavy quark limit, a doubly heavy baryon is regarded as composed of a heavy diquark and a light quark. We establish the Bethe-Salpeter (BS) equations for the heavy diquarks and the doubly heavy baryons, respectively, to leading order in a $1/m_{Q}$ expansion. The BS equations are solved numerically under the covariant instantaneous approximation with the kernels containing scalar confinement and one-gluon-exchange terms. The masses for the heavy diquarks and the doubly heavy baryons are obtained and the non-leptonic decay widths for the doubly heavy baryons emitting a pseudo-scalar meson are calculated within the model.Comment: Corrections to the text, two references added, version accepted for publication in Physical Review