Patterns of consumption in a discrete choice model with asymmetric interactions

We study the consumption behaviour of an asymmetric network of heterogeneous agents in the framework of discrete choice models with stochastic decision rules. We assume that the interactions among agents are uniquely specified by their ``social distance'' and consumption is driven by peering, distinction and aspiration effects. The utility of each agent is positively or negatively affected by the choices of other agents and consumption is driven by peering, imitation and distinction effects. The dynamical properties of the model are explored, by numerical simulations, using three different evolution algorithms with: parallel, sequential and random-sequential updating rules. We analyze the long-time behaviour of the system which, given the asymmetric nature of the interactions, can either converge into a fixed point or a periodic attractor. We discuss the role of symmetric versus asymmetric contributions to the utility function and also that of idiosyncratic preferences, costs and memory in the consumption decision of the agents.Comment: 11 pages, 9 figures, presented at "Complex Behaviour in Economics" Aix-en-Provence 3-7 May, 2000. Minor modifications made: references added and typos corrected. This paper is a fully revised version to the one previously submitted as cond-mat/990913

Comment on "The Phenomenology of a Nonstandard Higgs Boson in W_L W_L Scattering"

We show that in Composite Higgs models, the coupling of the Higgs resonance to a pair of $W$ bosons is weaker than the corresponding Standard Model coupling, provided the Higgs arises from electroweak doublets only. This is partly due to the effects of the nonlinear realization of the chiral symmetries at the compositeness scale.Comment: 6 pages, BU-HEP 94-2

The profile of a nonstandard Higgs boson at the LHC

In a wide class of extensions of the Standard Model there is a scalar resonance with the quantum numbers of the usual Higgs boson but with different couplings to fermions and gauge bosons. Using an effective Lagrangian description, we examine the phenomenology of such a generic nonstandard Higgs boson at the LHC. In particular, we determine the circumstances under which such a particle can be observed in its $ZZ$ decay mode and distinguished from the Higgs boson of the Standard Model. We briefly comment on the energy scale effectively probed at the LHC, if the nonstandard nature of an observed Higgs particle can be asserted.Comment: 21 pages, Latex, no figure

Carta del Dr. Vassilis Koulovassilopoulos a Javier Pascual, Subdirector General de Universidades e Investigación (Madrid) demanant pròrroga de la seva beca

Relacionats amb 09/010

Currículum Vitae de Vassilios Koulovassilopoulos (Boston University, EUA)

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PATTERNS OF CONSUMPTION IN DISCRETE CHOICE MODELS WITH ASYMMETRIC INTERACTIONS

A common feature of many aggregate variables in economics and finance is that they exhibit oscillatory behaviour, showing boom-and-bust patterns. Examples are fad and bandwagon behaviour in sociology, business cycles in economics, bubbles in stock market prices, wave behaviour in the adoption of innovation technology.We study consumption behaviour in systems with heterogeneous interacting agents. Two different models are introduced, respectively with long and short range interactions among agents. At any time step an agent decides whether or not to consume a good, doing so if this provides positive utility. Utility is affected by idiosyncratic preferences (noise) and costs as well as externalities from other agents. Agents are ranked in classes, with interactions among agents depending on the agents' ``distance'' (such as, for example, differences in wealth), and they recognize peer, distinction and aspiration groups. We simulate the system numerically for different choices of the parameters as well as for different class (wealth) distributions and identify different complex patterns: a steady state regime with a variety of consumption modes of behaviour, and a wave/cycle regime. The cases of fashion (fad) and value goods are both analyzed.The crucial point in this model is not the exact description of individual behaviour but the interrelation between individuals and the statistical properties of consumers' characteristics. We want to identify which are the relevant mechanisms that determine the large scale behaviour of aggregate consumption. In our model the macro-level organization, manifests in complex consumption patterns, which emerge purely from the micro-level interactions among agents, without the coordinating effect of any aggregate signal.Particular emphasis is given to the dynamical properties of the model, and we provide examples of complex patterns, such as non-periodic consumption cycles and turbulent behaviour with boom and busts in consumption activity. Our model bears resemblance with models of statistical mechanics of disordered systems and provides an example of how the development of appropriate numerical approaches may provide fundamental advances in the understanding of the complex behaviour that arise from the nonlinear spatio-temporal interactions among a large number of units.