Quasicrystals, model sets, and automatic sequences

We survey mathematical properties of quasicrystals, first from the point of view of harmonic analysis, then from the point of view of morphic and automatic sequences. Nous proposons un tour d'horizon de propri\'et\'es math\'ematiques des quasicristaux, d'abord du point de vue de l'analyse harmonique, ensuite du point de vue des suites morphiques et automatiques

Non-Gaussian eccentricity fluctuations

We study the fluctuations of the anisotropy of the energy density profile created in a high-energy collision at the LHC. We show that the anisotropy in harmonic $n$ has generic non-Gaussian fluctuations. We argue that these non-Gaussianities have a universal character for small systems such as p+Pb collisions, but not for large systems such as Pb+Pb collisions where they depend on the underlying non-Gaussian statistics of the initial density profile. We generalize expressions for the eccentricity cumulants $\varepsilon_2\{4\}$ and $\varepsilon_3\{4\}$ previously obtained within the independent-source model to a general fluctuating initial density profile.Comment: 14 pages. Minor revisio

Continuous description of fluctuating eccentricities

We consider the initial energy density in the transverse plane of a high energy nucleus-nucleus collision as a random field \rho(\x), whose probability distribution $P[\rho]$, the only ingredient of the present description, encodes all possible sources of fluctuations. We argue that it is a local Gaussian, with a short-range 2-point function, and that the fluctuations relevant for the calculation of the eccentricities that drive the anisotropic flow have small relative amplitudes. In fact, this 2-point function, together with the average density, contains all the information needed to calculate the eccentricities and their variances, and we derive general model independent expressions for these quantities. The short wavelength fluctuations are shown to play no role in these calculations, except for a renormalization of the short range part of the 2-point function. As an illustration, we compare to a commonly used model of independent sources, and recover the known results of this model

Correlations in the Monte Carlo Glauber model

Event-by-event fluctuations of observables are often modeled using the Monte Carlo Glauber model, in which the energy is initially deposited in sources associated with wounded nucleons. In this paper, we analyze in detail the correlations between these sources in proton-nucleus and nucleus-nucleus collisions. There are correlations arising from nucleon-nucleon correlations within each nucleus, and correlations due to the collision mechanism, which we dub twin correlations. We investigate this new phenomenon in detail. At the RHIC and LHC energies, correlations are found to have modest effects on size and eccentricity fluctuations, such that the Glauber model produces to a good approximation a collection of independent sources.Comment: minor improvements, 14 pages, 9 figure

Restricted and Unrestricted Dominance for Welfare, Inequality and Poverty Orderings

This paper extends the previous literature on the normative links between the measurement of poverty, social welfare and inequality. We show how, when the range of possible poverty lines is unbounded above, a robust ranking of absolute poverty may be interpreted as a robust ranking of social welfare, and a robust ranking of relative poverty may be interpreted as a robust ranking of inequality for any order of stochastic dominance. This interpretation is also valid when the maximum poverty line is bounded and for certain orders of stochastic dominance, so long as social welfare and inequality judgements are "censored". We also develop new criteria of restricted inequality dominance, and find that they warn against the use of some popular indices of relative poverty and censored inequality. Finally, we illustrate geometrically how the new criteria of restricted inequality dominance extends the rankings power of previously proposed dominance criteria.Welfare, Inequality, Poverty, Stochastic Dominance

Restricted and Unrestricted Dominance for Welfare, Inequality and Poverty Orderings

This paper extends the previous literature on the ethical links between the measurement of poverty, social welfare and inequality. We show inter alia, how, when the range of possible poverty lines is unbounded above, a robust ranking of absolute poverty may be interpreted as a robust ranking of social welfare, and a robust ranking of relative poverty may be intepreted as a robust ranking of inequality, and this, for any order of stochastic dominance.Welfare, Inequality, Poverty, Stochastic Dominance

Transverse energy fluctuations and the pattern of J/Psi suppression in Pb-Pb collisions

The NA50 collaboration has recently observed that the J/psi production rate in Pb-Pb collisions decreases more rapidly as a function of the transverse energy for the most central collisions than for less central ones. We show that this phenomenon can be understood as an effect of transverse energy fluctuations in central collisions. A good fit of the data is obtained using a model which relates J/psi suppression to the local energy density. Our results suggest that the J/psi is completely suppressed at the highest densities achieved in Pb-Pb collisions.Comment: v2, 4 pages, LaTeX, 3 eps figures include

J/Psi suppression in central Pb-Pb collisions

We discuss the recent NA50 J/Psi production data in Pb--Pb collisions, in particular the second drop at high transverse energies which correspond to the most central collisions. Using a model which relates the J/Psi suppression to the local energy density, we show that the data can be explained by taking into account transverse energy fluctuations at a given impact parameter. Predictions of this model for RHIC are briefly discussed.Comment: to appear in the Proceedings of Quark Matter'200