Star-Invertibility and tt-finite character in Integral Domains

Let $A$ be an integral domain. We study new conditions on families of integral ideals of $A$ in order to get that $A$ is of $t$-finite character (i.e., each nonzero element of $A$ is contained in finitely many $t$-maximal ideals). We also investigate problems connected with the local invertibility of ideals.Comment: 16 page

Stability and Clifford regularity with respect to star operations

In the last few years, the concepts of stability and Clifford regularity have been fruitfully extended by using star operations. In this paper we deepen the study of star stable and star regular domains and relate these two classes of domains to each other.Comment: 22 pages; Comm. Alg., 201

I beni culturali di interesse religioso nella nuova legislazione statale: le innovazioni nell'Intesa con la Conferenza episcoipale italiana

La nuova Intesa tra il Ministro per i Beni e le Attivit\ue0 culturali ed il Presidente della Conferenza episcopale italiana si \ue8 resa necessaria a seguito dell\u2019entrata in vigore del d.lgs. 22 gennaio 2004, n. 42 (Codice dei beni culturali e del paesaggio) e della l. cost. 18 ottobre 2001, n. 3 (modifiche al Titolo V della Costituzione). Sul piano strutturale il documento, in diverse circostanze, ripropone i contenuti sostanziali dell\u2019Intesa del 1996 (che trascurer\uf2 in quanto diffusamente trattati dalla dottrina) ma in pi\uf9 punti \uabaggiorna\ubb e \uabintegra\ubb, per usare la stessa terminologia adottata in sede di sottoscrizione, i contenuti della precedente Intesa. Pertanto in questa sede cercher\uf2 di evidenziare e circoscrivere alcune criticit\ue0 di sistema, se tali saranno anche nelle applicazioni, in rapporto alle intervenute innovazioni legislative

The Cosmic Ray Signature of Dark Matter Caustics

Gravitational collapse of dark matter, merger of dark matter haloes and tidal disruption of satellites are among processes which lead to the formation of fine and dense dark matter shells, also known as dark matter caustics. The putative weakly interacting species which may form the dark matter are expected to strongly annihilate in these dense regions of the Milky Way halo and generate in particular antiprotons and positrons. We derive the flux of these rare antimatter particles at the Earth and show that it depends significantly on the cut-off radius of the dark matter distribution at the galactic centre. Boost factors of ~30 are found with respect to a smooth NFW profile for high-energy antiprotons and low-energy positrons if this cut-off radius is taken to be 300 pc -- a somewhat extreme value though. This yields a detectable antiproton signal around hundreds of Gev in models where the annihilation cross section today is enhanced by non--perturbative effects as in the generic case of a heavy Wino. However, dark matter caustics cannot provide a better explanation for the HEAT excess reported above ~10 GeV than a smooth NFW or isothermal cored distribution.Comment: 16 pages, 11 figures, version to appear in MNRA

Galactic secondary positron flux at the Earth

Secondary positrons are produced by spallation of cosmic rays within the interstellar gas. Measurements have been typically expressed in terms of the positron fraction, which exhibits an increase above 10 GeV. Many scenarios have been proposed to explain this feature, among them some additional primary positrons originating from dark matter annihilation in the Galaxy. The PAMELA satellite has provided high quality data that has enabled high accuracy statistical analyses to be made, showing that the increase in the positron fraction extends up to about 100 GeV. It is therefore of paramount importance to constrain theoretically the expected secondary positron flux to interpret the observations in an accurate way. We find the secondary positron flux to be reproduced well by the available observations, and to have theoretical uncertainties that we quantify to be as large as about one order of magnitude. We also discuss the positron fraction issue and find that our predictions may be consistent with the data taken before PAMELA. For PAMELA data, we find that an excess is probably present after considering uncertainties in the positron flux, although its amplitude depends strongly on the assumptions made in relation to the electron flux. By fitting the current electron data, we show that when considering a soft electron spectrum, the amplitude of the excess might be far lower than usually claimed. We provide fresh insights that may help to explain the positron data with or without new physical model ingredients. PAMELA observations and the forthcoming AMS-02 mission will allow stronger constraints to be aplaced on the cosmic--ray transport parameters, and are likely to reduce drastically the theoretical uncertainties.Comment: 15 pages, 12 figures. The recent PAMELA data on the positron fraction (arXiv:0810.4995) have been included and the ensuing discussion has been extended. Accepted version in A&