Unital hyperarchimedean vector lattices

We prove that the category of unital hyperarchimedean vector lattices is equivalent to the category of Boolean algebras. The key result needed to establish the equivalence is that, via the Yosida representation, such a vector lattice is naturally isomorphic to the vector lattice of all locally constant real-valued continuous functions on a Boolean (=compact Hausdorff totally disconnected) space. We give two applications of our main result.Comment: 15 pages. Submitted pape

Mean-field phase diagram of the 1-D Bose gas in a disorder potential

We study the quantum phase transition of the 1D weakly interacting Bose gas in the presence of disorder. We characterize the phase transition as a function of disorder and interaction strengths, by inspecting the long-range behavior of the one-body density matrix as well as the drop in the superfluid fraction. We focus on the properties of the low-energy Bogoliubov excitations that drive the phase transition, and find that the transition to the insulator state is marked by a diverging density of states and a localization length that diverges as a power-law with power 1. We draw the phase diagram and we observe that the boundary between the superfluid and the Bose glass phase is characterized by two different algebraic relations. These can be explained analytically by considering the limiting cases of zero and infinite disorder correlation length.Comment: 10 pages, 10 figure

Dilution of zero point energies in the cosmological expansion

The vacuum fluctuations of all quantum fields filling the universe are supposed to leave enormous energy and pressure contributions which are incompatible with observations. It has been recently suggested that, when the effective nature of quantum field theories is properly taken into account, vacuum fluctuations behave as a relativistic gas rather than as a cosmological constant. Accordingly, zero-point energies are tremendously diluted by the universe expansion but provide an extra contribution to radiation energy. Ongoing and future cosmological observations could offer the opportunity to scrutinize this scenario. The presence of such additional contribution to radiation energy can be tested by using primordial nucleosynthesis bounds or measured on Cosmic Background Radiation anisotropy.Comment: 8 pages, no figures. Submitted the 17th of March to Modern Physics Letters

A systematic phenomenological study of the cos⁡2ϕ\cos 2 \phi asymmetry in unpolarized semi--inclusive DIS

We study the $\cos 2 \phi$ azimuthal asymmetry in unpolarized semi-inclusive DIS, taking into account both the perturbative contribution (gluon emission and splitting) and the non perturbative effects arising from intrinsic transverse motion and transverse spin of quarks. In particular we explore the possibility to extract from some information about the Boer--Mulders function $h_1^{\perp}$, which represents a transverse--polarization asymmetry of quarks inside an unpolarized hadron. Predictions are presented for the HERMES, COMPASS and JLab kinematics, where is dominated by the kinematical higher--twist contribution, and turns to be of order of few percent. We show that a larger asymmetry in $\pi^-$ production, compared to $\pi^+$ production, would represent a signature of the Boer--Mulders effect.Comment: 14 pages, 12 figure

A twisted conformal field theory description of the Quantum Hall Effect

We construct an effective conformal field theory by using a procedure which induces twisted boundary conditions for the fundamental scalar fields. That allows to describe a quantum Hall fluid at Jain hierarchical filling, nu=m/(2pm+1), in terms of one charged scalar field and m-1 neutral ones. Then the resulting algebra of the chiral primary fields is U(1)xW_m. Finally the ground state wave functions are given as correlators of appropriate composite fields (a-electrons).Comment: 11 pages, plain Late

Monitoraggio della diga “Castello” di Bivona (AG) con tecniche GNSS

Le dighe di grandi dimensioni, di terra o di cemento, sono infrastrutture che rivestono un ruolo critico nella fornitura idrica e nella produzione energetica. Come è noto in letteratura, il carico e lo scarico delle forze sottopone la diga a elevate sollecitazioni strutturali che devono essere monitorate. Queste possono essere dovute alle fluttuazioni del livello dell'acqua, all'assestamento della struttura, all'attività di frane situate nelle vicinanze o all'attività sismica. Rilevare preventivamente i potenziali problemi consente di adottare le misure necessarie per evitare che si verifichi una catastrofe, o mitigarne gli effetti. Il lavoro proposto è in corso di svolgimento presso il Dipartimento di Ingegneria Civile, Ambientale Aerospaziale, dei Materiali (DICAM) dell'Università degli Studi di Palermo e ha come scopo il monitoraggio della Diga “Castello”, sbarramento di materiali sciolti situato tra i comuni di Bivona e Alessandria della Rocca in provincia di Agrigento, mediante il posizionamento sul coronamento di tre ricevitori GNSS. Le antenne sono state monumentate su appositi pilastrini in acciaio fissati al suolo mediante piccola fondazione in cls; il rate impostato ai ricevitori è stato di 30 sec., l'angolo di cut-off di 10°. La campagna di rilevamento è in corso e ad oggi sono stati archiviati 12 mesi di dati con cadenza settimanale. Verificata la buona qualità dei dati a disposizione si è proceduto con l'elaborazione degli stessi mediante i software NDA Professional e Bernese GPS 5.0