Methods and Techniques for Quali-Quantitative Analyses: an Agricultural Application

[En] This paper describes a dynamic systems model which links the private and public functions of agriculture with the territorial development of rural regions and quality of life of rural residents. Among the key results are the quantification of a set of economic, social and environmental outcomes which follow from a set of EU policy scenarios for the period 2013. [It] L’articolo descrive un modello dinamico di sistema che lega le funzioni private e pubbliche dell’agricoltura con lo sviluppo territoriale delle regioni rurali e con la qualità della vita dei residenti. Tra i risultati principali vi è la quantificazione degli effetti economici, sociali e ambientali generati da un insieme di scenari di politiche comunitarie per il 2013. [Fr] L’article décrit un modèle dynamique de système qui lie les fonctions privées et publiques de l'agriculture avec le développement territorial des régions rurales et avec la qualité de la vie des résidants. Parmi les résultats principaux on a la quantification des effets sociaux, environnementaux et économiques générés par un ensemble de scénarios de politiques pour le 2013.POMMARD, Dynamic Systems Model, Multifunctional Agriculture, Rural Development, Quality of Life, Policies

Strong Interaction Effects in Stop Pair Production at e+e−e^+ e^- Colliders

We discuss perturbative and non-perturbative strong interaction effects in the pair production of stop squarks ($\tilde{t}_1$) at $e^+ e^-$ colliders. Events with an additional hard gluon allow to detect or exclude stop pair production even in scenarios with very small mass splitting between $\tilde{t}_1$ and an invisible lightest supersymmetric particle (LSP). Such events can also help to establish that $\tilde{t}_1$ transforms as a triplet under $SU(3)_C$. We also carefully study non-perturbative $\tilde{t}_1$ fragmentation, which is currently not well understood: not only is the $\tilde{t}_1$ fragmentation function not known very well, but also there are ambiguities in the algorithm employed to model fragmentation. We present numerical results both for CERN LEP-183 and for a proposed future $e^+ e^-$ collider operating at center-of-mass energy $\sqrt{s}=500$ GeV.Comment: 16 pages and 4 figure

Quantum evolution of scalar fields in Robertson-Walker space-time

We study the $\lambda \phi^4$ field theory in a flat Robertson-Walker space-time using the functional Sch\"odinger picture. We introduce a simple Gaussian approximation to analyze the time evolution of pure states and we establish the renormalizability of the approximation. We also show that the energy-momentum tensor in this approximation is finite once we consider the usual mass and coupling constant renormalizations.Comment: Revtex file, 19 pages, no figures. Compressed ps version available at http://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-912.ps.Z or at ftp://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-912.ps.

Assessing the Economic Impacts of Climate Change. An Updated CGE Point of View

The present research describes a climate change integrated impact assessment exercise, whose economic evaluation is based on a CGE approach and modeling effort. Input to the CGE model comes from a wide although still partial set of up-to-date bottom-up impact studies. Estimates indicate that a temperature increase of 1.92°C compared to pre-industrial levels in 2050 could lead to global GDP losses of approximately 0.5% compared to a hypothetical scenario where no climate change is assumed to occur. Northern Europe is expected to benefit from the evaluated temperature increase (+0.18%), while Southern and Eastern Europe are expected to suffer from the climate change scenario under analysis (-0.15% and -0.21% respectively). Most vulnerable countries are the less developed regions, such as South Asia, South-East Asia, North Africa and Sub-Saharan Africa. In these regions the most exposed sector is agriculture, and the impact on crop productivity is by far the most important source of damages. It is worth noting that the general equilibrium estimates tend to be lower, in absolute terms, than the bottom-up, partial equilibrium estimates. The difference is to be attributed to the effect of market-driven adaptation. This partly reduces the direct impacts of temperature increases, leading to lower damage estimates. Nonetheless these remain positive and substantive in some regions. Accordingly, market-driven adaptation cannot be the solution to the climate change problem.Computable General Equilibrium Modeling, Impact Assessment, Climate Change

Signals of Two Universal Extra Dimensions at the LHC

Extensions of the standard model with universal extra dimensions are interesting both as phenomenological templates as well as model-building fertile ground. For instance, they are one the prototypes for theories exhibiting compressed spectra, leading to difficult searches at the LHC since the decay products of new states are soft and immersed in a large standard model background. Here we study the phenomenology at the LHC of theories with two universal extra dimensions. We obtain the current bound by using the production of second level excitations of electroweak gauge bosons decaying to a pair of leptons and study the reach of the LHC Run~II in this channel. We also introduce a new channel originating in higher dimensional operators and resulting in the single production of a second level quark excitation. Its subsequent decay into a hard jet and lepton pair resonance would allow the identification of a more model-specific process, unlike the more generic vector resonance signal. We show that the sensitivity of this channel to the compactification scale is very similar to the one obtained using the vector resonance.Comment: 11 pages and 6 figure

Climate Change Feedback on Economic Growth: Explorations with a Dynamic General Equilibrium Model

Human-generated greenhouse gases depend on the level of economic activity. Therefore, most climate change studies are based on models and scenarios of economic growth. Economic growth itself, however, is likely to be affected by climate change impacts. These impacts affect the economy in multiple and complex ways: changes in productivity, resource endowments, production and consumption patterns. We use a new dynamic, multi-regional Computable General Equilibrium (CGE) model of the world economy to answer the following questions: Will climate change impacts significantly affect growth and wealth distribution in the world? Should forecasts of human-induced greenhouse gases emissions be revised, once climate change impacts are taken into account? We found that, even though economic growth and emission paths do not change significantly at the global level, relevant differences exist at the regional and sectoral level. In particular, developing countries appear to suffer the most from climate change impacts.Computable General Equilibrium Models, Climate Change, Economic Growth

Physics at High Energy Photon Photon Colliders

I review the physics prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking.Comment: 18 pages, no figures, plain latex (run twice), LBL-3577

REDD in the Carbon Market: A General Equilibrium Analysis

Deforestation is a major source of CO2 emissions, accounting for around 17% of total annual anthropogenic carbon release. While the cost estimates of reducing deforestation rates vary considerably depending on model assumptions, it is widely accepted that emissions reductions from avoided deforestation consist of a relatively low cost mitigation option. Halting deforestation is therefore not only a major ecological challenge, but also a great opportunity to cost effectively reduce climate change negative impacts. In this paper we analyze the impact of introducing avoided deforestation credits into the European carbon market using a multiregional Computable General Equilibrium model – the ICES model (Inter-temporal Computable Equilibrium System). Taking into account political concerns over a possible “flooding” of REDD credits, various limits to the number of REDD allowances entering the carbon market are considered. Finally, unlike previous studies, we account for both direct and indirect effects occurring on land and timber markets resulting from lower deforestation rates. We conclude that avoided deforestation notably reduces climate change policy costs - by approximately 80% with unlimited availability of REDD credits - and may drastically reduce carbon prices. Policy makers may, however, effectively control for these imposing limits to avoided deforestation credits use. Moreover, avoided deforestation has the additional positive effect of reducing carbon leakage of a unilateral European climate change policy. This is good news for the EU, but not necessarily for REDD regions. Indeed we show that REDD revenues are not sufficient to compensate REDD regions for a less leakage-affected and more competitive EU in international markets. In fact, REDD regions would prefer to free ride on the EU unilateral mitigation policy.Forestry, Avoided Deforestation, Climate Change, Emission Trading, General Equilibrium Modelling