Massless Particles in Arbitrary Dimensions

Various properties of two kinds of massless representations of the n-conformal (or (n+1)-De Sitter) group $\tilde{G}_n=\widetilde{SO}_0(2,n)$ are investigated for $n\ge2$. It is found that, for space-time dimensions $n\ge3$, the situation is quite similar to the one of the n=4 case for $S_n$-massless representations of the n-De Sitter group $\widetilde{SO}_0(2,n-1)$. These representations are the restrictions of the singletons of $\tilde{G}_n$. The main difference is that they are not contained in the tensor product of two UIRs with the same sign of energy when n>4, whereas it is the case for another kind of massless representation. Finally some examples of Gupta-Bleuler triplets are given for arbitrary spin and $n\ge3$.Comment: 33 pages, LaTeX2e. To be published in Reviews in Math. Phy

An extensible web interface for databases and its application to storing biochemical data

This paper presents a generic web-based database interface implemented in Prolog. We discuss the advantages of the implementation platform and demonstrate the system's applicability in providing access to integrated biochemical data. Our system exploits two libraries of SWI-Prolog to create a schema-transparent interface within a relational setting. As is expected in declarative programming, the interface was written with minimal programming effort due to the high level of the language and its suitability to the task. We highlight two of Prolog's features that are well suited to the task at hand: term representation of structured documents and relational nature of Prolog which facilitates transparent integration of relational databases. Although we developed the system for accessing in-house biochemical and genomic data the interface is generic and provides a number of extensible features. We describe some of these features with references to our research databases. Finally we outline an in-house library that facilitates interaction between Prolog and the R statistical package. We describe how it has been employed in the present context to store output from statistical analysis on to the database.Comment: Online proceedings of the Joint Workshop on Implementation of Constraint Logic Programming Systems and Logic-based Methods in Programming Environments (CICLOPS-WLPE 2010), Edinburgh, Scotland, U.K., July 15, 201

Masslessness in nn-dimensions

We determine the representations of the ``conformal'' group ${\bar{SO}}_0(2, n)$, the restriction of which on the ``Poincar\'e'' subgroup ${\bar{SO}}_0(1, n-1).T_n$ are unitary irreducible. We study their restrictions to the ``De Sitter'' subgroups ${\bar{SO}}_0(1, n)$ and ${\bar{SO}}_0(2, n-1)$ (they remain irreducible or decompose into a sum of two) and the contraction of the latter to ``Poincar\'e''. Then we discuss the notion of masslessness in $n$ dimensions and compare the situation for general $n$ with the well-known case of 4-dimensional space-time, showing the specificity of the latter.Comment: 34 pages, LaTeX2e, 1 figure. To be published in Reviews in Math. Phy

Fiscal Policy, Rent Seeking and Growth under Electoral Uncertainty Theory and Evidence from the OECD

We construct a general equilibrium model of economic growth and optimally chosen fiscal policy, in which individuals compete with each other for a share of government spending and two political parties can alternate in power according to an exogenous reelection probability. The main prediction is that uncertainty about remaining in power results in increased fiscal spending, which in turn distorts incentives by pushing individuals away from productive work to rent-seeking activities; then distorted incentives hurt growth. This receives empirical support in a dataset of 25 OECD countries over the period 1982-1996. In particular, electoral uncertainty leads to larger government consumption shares in GDP, which in turn exert an adverse effect on the ICRG index measuring incentives and this is bad for growth. Actually, estimation by IV methods and confidence intervals that are robust to (potentially) weak instruments, reveal that OLS under-estimates the effects of government spending on rent extraction activities and of such activities on economic growth.Fiscal policy; rent seeking; economic growth; elections.

The Role of Government in Anti-Social Redistributive Activities

It is known that anti-social redistributive activities (rent seeking, tax evasion, corruption, violation of property rights, delay of socially beneficial reforms, etc) hurt the macroeconomy. But it is less known what is the role of government size as a determinant of such activities. We use data from 64 counties (both developed and developing) in 5-year periods over 1980-2000. As a measure of anti-social activities, we use the ICRG index; as a measure of government size, we use the government share in GDP; and as a measure of government efficiency, we construct an index by following the methodology of Afonso, Schuknecht and Tanzi (2003). Our regressions show that what really matters to social incentives is the relation between size and efficiency. Specifically, while a larger size of government is bad for incentives when one ignores efficiency, the results change drastically when government efficiency is also taken into account. Only when our measure of size exceeds our measure of efficiency, larger public sectors are bad for incentives. By contrast, when efficiency exceeds size, larger public sectors are not bad; actually, in the case where efficiency is measured by government performance in the policy areas of administration, stabilization and infrastructure, larger public sectors significantly improve incentives.government and behaviour of agents, collective decision-making

Rent Seeking, Policy and Growth under Electoral Uncertainty: Theory and Evidence

We construct an otherwise standard general equilibrium model of economic growth and endogenously chosen fiscal policy, in which individuals compete with each other for extra fiscal transfers and two political parties compete with each other for staying in power. The main prediction is that relatively large public sectors in pre-election periods distort incentives by pushing individuals away from productive work to rent seeking activities. In turn, distorted incentives hurt growth. We test this prediction by using a panel data set of a group of 25 OECD countries over the period 1982-1996, as well as a cross-section of 108 industrial and developing countries over the decade 1990-2000. There is evidence that electoral and/or political instability cause relatively large public sectors, which in turn increase rent seeking (as measured by the ICRG index), and this is bad for economic growth.Political uncertainty, economic growth, incentives