Assessing the performance of social spending in Europe

Based on the construction of a new composite index to assess the relative performance of welfare policies, we show that the variability of performances cannot be explained only by the amount of resources devoted to social policies, but also by its composition: countries with higher shares of social public expenditure, specifically aimed at reducing income concentration, obtain better results. This associates the traditional classification of the welfare systems to the performance obtained in the social sector

Defect Formation Rates in Cosmological First-Order Phase Transitions

In cosmological first-order phase transitions, the progress of true-vacuum bubbles is expected to be significantly retarded by the interaction between the bubble wall and the hot plasma. It has been claimed that this leads to a significant reduction in the number of topological defects formed per bubble, as a result of phase equilibration between bubbles. This claim has been verified for spontaneously-broken global symmetries. We perform a series of simulations of complete phase transitions in the 2+1-dimensional U(1)-Abelian Higgs model, for a range of bubble wall velocities, in order to obtain a quantitative measure of the effect of bubble wall speed on the number density of topological defects. We find that the number of defects formed is i) significantly lower in the local than the global case and ii) decreases exponentially as a function of wall velocity. Slow-moving bubbles also lead, however, to the nucleation of more bubbles before the phase transition is complete. Our simulations show that this is in fact the dominant effect, and so we predict {\em more} defects per unit volume as a result of the sub-luminal bubble wall terminal velocity.Comment: 9 pages, 5 figures. Replaced with version to appear in Physical Review

Transverse-momentum resummation for Higgs boson pair production at the LHC with top-quark mass effects

We consider Higgs boson pair production via gluon fusion in hadronic collisions. We report the calculation of the transverse-momentum ($q_T$) distribution of the Higgs boson pair with top-quark mass ($M_t$) effects fully taken into account. At small values of $q_T$ we resum the logarithmically-enhanced perturbative QCD contributions up to next-to-leading logarithmic (NLL) accuracy. At intermediate and large values of $q_T$ we consistently combine resummation with the ${\cal O}(\alpha_S^3)$ fixed-order results. After integration over $q_T$, we recover the next-to-leading order (NLO) result for the inclusive cross section with full dependence on $M_t$. We present illustrative numerical results at LHC energies, together with an estimate of the corresponding perturbative uncertainties, and we study the impact of the top-quark mass effects.Comment: 11 pages, 2 figures, matches version published in JHE

Inf-convolution and regularization of convex functions on Riemannian manifolds of nonpositive curvature

We show how an operation of inf-convolution can be used to approximate convex functions with $C^{1}$ smooth convex functions on Riemannian manifolds with nonpositive curvature (in a manner that not only is explicit but also preserves some other properties of the original functions, such as ordering, symmetries, infima and sets of minimizers), and we give some applications.Comment: 17 page