Testing symmetries in effective models of higher derivative field theories

Higher derivative field theories with interactions raise serious doubts about their validity due to severe energy instabilities. In many cases the implementation of a direct perturbation treatment to excise the dangerous negative-energies from a higher derivative field theory may lead to violations of Lorentz and other symmetries. In this work we study a perturbative formulation for higher derivative field theories that allows the construction of a low-energy effective field theory being a genuine perturbations over the ordinary-derivative theory and having a positive-defined Hamiltonian. We show that some discrete symmetries are recovered in the low-energy effective theory when the perturbative method to reduce the negative-energy degrees of freedom from the higher derivative theory is applied. In particular, we focus on the higher derivative Maxwell-Chern-Simons model which is a Lorentz invariant and parity-odd theory in 2+1 dimensions. The parity violation arises in the effective action of QED$_3$ as a quantum correction from the massive fermionic sector. We obtain the effective field theory which remains Lorentz invariant, but parity invariant to the order considered in the perturbative expansion.Comment: 13 pages, Sec. III, additional references added, P symmetry revised, accepted for publication in PR

When Lisbon met the Team 10 Cluster City

After the Doorn Manifesto (1954), Team 10 members synthesize their earlier projects into a new urban model: the Cluster City. In 1961, the Lisbon Technical Office for Housing (Gabinete Técnico de Habitação) – GTH was established by the municipality to resolve an ongoing housing shortage. Soon, the GTH planned the urbanization of the Chelas Valley, an agricultural area in the East area of Lisbon. This plan tested approaches to neighbourhood planning unprecedented in the municipality. Its Zone I Plan, by Francisco Silva Dias and Luís Vassalo Rosa (1966) was the first to be implemented, echoing in practice the Doorn Manifesto. Here, we identify urban forms used in this Plan, and the ‘ground rules’ that structured it and influenced its change over time. Furthermore, we ask whether Chelas can shed some light in the recent demise of examples like Toulouse-Le Mirail and Robin Hood Gardens.info:eu-repo/semantics/publishedVersio

The role of food in re-imagining the city: From the neighbourhood to the region

Humanity is now believed to live in a new geological epoch, the Anthropocene, as changes have been reported on the atmosphere, air, water, and soil, but also on societal perceptions of these issues. This presentation departs from the theoretical assumption that the impact of the abovementioned changes on culture and the environment have not yet found a stable influence on urban planning. This presentation overviews the implications of the food system within urban planning while considering it as a socio-technical system which integrates production, distribution, transformation, consumption and disposal patterns. The production phase of the food system in particular, emerges as a fundamental planning challenge, extending to urban form solutions, individual behaviours, dietary regimes, inequalities in foodsheds planning, and the cultural capital of food. Accordingly, the food system emerges here as an opportunity to identify how current urban fabrics of cities and their rural and regional hinterlands can be transformed in terms of their metabolic function and respond to the needs of people and the environment. To do so, this presentation introduces the preliminary results of an analysis conducted by an ongoing research project SPLACH – Spatial Planning for Change, at two particular scales: the region and the neighbourhood. Thus, while focusing in the Lisbon Metropolitan Area (LMA), in Portugal, we provide an analysis of the Regional Plan as well as of specific residential neighbourhoods located in LMA, regarding the relationship between the food system functioning and urban planning approaches. The analysis includes a comparative number of case studies which differ in urban form solutions, socio-economic conditions, but also geographical location. The results support the request for a stronger integration of the above-identified underexplored topics of the food system within urban planning, which will be fundamental to inform a new theory of the city that makes any serious contribution towards a sustainability transition.info:eu-repo/semantics/publishedVersio

Generalized Path Dependent Representations for Gauge Theories

A set of differential operators acting by continuous deformations on path dependent functionals of open and closed curves is introduced. Geometrically, these path operators are interpreted as infinitesimal generators of curves in the base manifold of the gauge theory. They furnish a representation with the action of the group of loops having a fundamental role. We show that the path derivative, which is covariant by construction, satisfies the Ricci and Bianchi identities. Also, we provide a geometrical derivation of covariant Taylor expansions based on particular deformations of open curves. The formalism includes, as special cases, other path dependent operators such as end point derivatives and area derivatives.Comment: 15 pages,2 figures, section 5, typos; To be published in J. Math. Phys. vol.48, 200

Mapping sustainability transitions in contemporary culture

This presentation draws from research conducted at an ongoing project, ‘SPLACH – Spatial Planning for Change’, which aims to inform a sustainability transition of the Lisbon Metropolitan Area urban planning, towards an improved food system, responding to contemporary cultural concerns. But where does contemporary culture really stand with respect to sustainability? Among many contenders for supplanting postmodernism, we would emphasize hypermodernism, digimodernism, metamodernism and transmodernism, since in many respects, these paradigmatic views are engaged with a sustainability transition. Here, we assess how history, technology and visual culture are valued in contemporaneity. This is done by intersecting our readings of cultural paradigms with key ideas about sustainability, drawn from the SPLACH literature review. Moreover, we highlight opportunities for urban design to accomodate a change towards sustainable urban environments.info:eu-repo/semantics/publishedVersio

Constraining CP violation in neutral meson mixing with theory input

There has been a lot of recent interest in the experimental hints of CP violation in B_{d,s}^0 mixing, which would be a clear signal of beyond the standard model physics (with higher significance). We derive a new relation for the mixing parameters, which allows clearer interpretation of the data in models in which new physics enters in M_12 and/or \Gamma_12. Our results imply that the central value of the D\O\ measurement of the semileptonic CP asymmetry in B_{d,s}^0 decay is not only in conflict with the standard model, but in a stronger tension with data on \Delta\Gamma_s than previously appreciated. This result can be used to improve the constraint on \Delta\Gamma or A_SL, whichever is less precisely measured.Comment: 5 pages, 2 figures, informed of prior derivation of eq. (21), title modifie

Chelas Zone J revisited: Urban morphology and change in a recovering neighbourhood

Among new council housing areas from 1960s Lisbon is the Chelas Valley, by then overwhelmingly agrarian. Although an integral urbanization plan - the Plano de Urbanização de Chelas (PUC) – was prepared until 1964, the area was divided into six zones, urbanized in different periods, with great deviances from the original plan. Upon construction, Chelas was challenged by social problems. One of the zones, Zone J, has been particularly associated with this negative image. The architectural designs by Tomás Taveira and Victor Consiglieri introduced changes to the urban plan by Francisco Silva Dias and José Lobo de Carvalho. After construction, several municipal initiatives tried to improve living conditions in Zone J, ranging from façade changes to demolitions. All along, it has been accepted that the urban form of Zone J was a determinant factor of its failure as a habitat. Here, we revisit the original Zone J Plan. How was it implemented, and how has it changed since? What has been the input of the residents in the territory they inhabit? Can it contribute to make Lisbon a more sustainable city? This presentation aims to answer these questions while trying to identify parallels with other urban areas in a crisis that share morphological characteristics with Chelas Zone J.info:eu-repo/semantics/publishedVersio

Designing for productive urban landscapes. Applying the CPUL concept in Lisbon Metropolitan Area

Designing for urban agriculture has been recently acknowledged as a young discipline requiring the attention of architects, urban designers, and planners to promote more sustainable urban cities and continuous productive landscapes. However, how to assess such landscape proposals? How can these be evaluated in terms of their social, ecological, and spatial dimensions? Based on the Continuous Productive Urban Landscape (CPUL) tool proposed by Bohn and Viljoen (2005) this presentation exposes a framework for action which could be applied in Lisbon Metropolitan Area (LMA) in order to evaluate the spatiality of its the contemporary food system and promote design solutions to improve it. In order to do so, this paper is organized into three parts. First, it introduces the problem under analysis and the case study. Secondly, it exposes how an analysis of urban agriculture, more precisely along the Lisbon - Vila Franca de Xira axis, contributed to expanding our understanding of the productive dimension of the LMA Food System and interrelates it to a morphological perspective. Finally, it introduces the CPUL concept and a possible application of it within the case study, with impact at the several stages of food system.info:eu-repo/semantics/publishedVersio

Where the fields have no name: urban-rural transitions in the Lisbon Region planning history

This paper discusses the existing urban-rural dichotomy in Portuguese urban planning, assuming its importance on food-provision, a basic human need. Our analysis stems from an historical overview at two scales, regional and municipal, within the Lisbon Region. Specifically, we identify key changes between two time-periods: the midtwentieth century, when design-based planning was established in Portugal for larger settlements, and nowadays, when it covers the totality of the national territory, based on land-use. We review these strategies, assessing what approaches would best encompass a sustainable transition of the food system. We start with the scheme of regional radial axis by architect Étienne de Gröer in contrast with the 2002 Lisbon Regional Plan. We furthermore expose two urbanization plans from 1940s: that of Vila Franca de Xira (1946) by Miguel Jacobetty and Faria da Costa and that of Palmela (1948) by João António Aguiar. Such plans, highly representative of the planning practices of that era, are then compared with their contemporary counterparts and subsequently with samples of their physical impacts on the ground, based on a morphological analysis of settlements and productive spaces in urban and rural contexts. Finally, we identify key changes for better use of productive soils within the Lisbon Region, considering challenges posed by international and national agendas.info:eu-repo/semantics/publishedVersio