A strong-coupling analysis of two-dimensional O(N) sigma models with N≥3N\geq 3 on square, triangular and honeycomb lattices

Recently-generated long strong-coupling series for the two-point Green's functions of asymptotically free ${\rm O}(N)$ lattice $\sigma$ models are analyzed, focusing on the evaluation of dimensionless renormalization-group invariant ratios of physical quantities and applying resummation techniques to series in the inverse temperature $\beta$ and in the energy $E$. Square, triangular, and honeycomb lattices are considered, as a test of universality and in order to estimate systematic errors. Large-$N$ solutions are carefully studied in order to establish benchmarks for series coefficients and resummations. Scaling and universality are verified. All invariant ratios related to the large-distance properties of the two-point functions vary monotonically with $N$, departing from their large-$N$ values only by a few per mille even down to $N=3$.Comment: 53 pages (incl. 5 figures), tar/gzip/uuencode, REVTEX + psfi

LAFOSSAITE E DIMORPHITE: DUE NUOVE SPECIE PER IL VESUVIO

La presenza di lafossaite, la cui località-tipo è il cratere de La Fossa all’Isola di Vulcano (Roberts et al., 2006), è stata rilevata su due piccoli campioni provenienti dal Vesuvio (eruzione del 1906), facenti parte di una vecchia collezione già appartenuta all’“Istituto Geomineralogico Italiano”, una società attiva negli anni ’20 del secolo scorso. Nei campioni esaminati la lafossaite forma minuscoli aggregati di cristalli cubici incolori, associati a realgar, dimorphite, anidrite e a un cloruro di tallio e arsenico attualmente in fase di studio. La dimorphite, la cui località-tipo è la Solfatara di Pozzuoli, fu descritta per la prima volta da Scacchi (1849) ed è associata a realgar e mascagnite

Parity effects in the scaling of block entanglement in gapless spin chains

We consider the Renyi alpha-entropies for Luttinger liquids (LL). For large block lengths l these are known to grow like ln l. We show that there are subleading terms that oscillate with frequency 2k_F (the Fermi wave number of the LL) and exhibit a universal power-law decay with l. The new critical exponent is equal to K/(2 alpha), where K is the LL parameter. We present numerical results for the anisotropic XXZ model and the full analytic solution for the free fermion (XX) point.Comment: 4 pages, 5 figures. Final version accepted in PR

Nuove specie minerali al Somma-Vesuvio: wulfenite

To the 247 species, of which 20 are doubtful, occurring at the Somma-Vesuvius volcanic complex, after the recent updating of the fluoro-edenite (despite the collecting ban) it has to be added the identification of a new common species, never occurred before. A sample belonging to Luigi Chiappino, found in 1989 at San Vito quarry, Ercolano, Napoli, was analyzed through SEM-EDX and the analysis identified the wulfenite on massive galena, as millimetrical, bipyramidal crystals, resinous, of yellow-orange colour, associated with calcite, cerussite and sphalerite

Ritrovamento di Atacamite in cristalli al Vesuvio

In the small vacuoles of an older lava from one of the quarries of Villa Inglese (Torre del Greco, Napoli) atacamite as crystalline have been discovered. This is a rare event in this volcanic complex

Nuovo ritrovamento di corindone al Monte Somma

After the occurrence described by of Balassone et al. (2001), a second finding of corundum, Al2O3, occurred in a small fragment of carbonatic rock at San Vito quarry, Ercolano, Napoli, Campania. It is the section of a 2 mm bluish crystal. The identification was done through SEM-EDX analysis at 30 kV excitation

Vulcano : tre secoli di mineralogia

Va ricordato, con immenso motivo di orgoglio e senza pecca di retorica, che il sito delle isole Eolie è “un eccezionale esempio dell’attività di costruzione e distruzione di isole operata dal vulcanesimo e testimoniano un fenomeno vulcanico tuttora in corso”, rivestendo “una importanza internazionale per la vulcanologia” e che, “studiate già a partire dal XVIII secolo, hanno fornito alle opere di vulcanologia la descrizione di due tipi di eruzione (vulcaniana e stromboliana)”, rappresentando da oltre due secoli, una tappa importante nella formazione di tutti i geologi: questa la motivazione suggellata dell’Unesco per il prestigioso riconoscimento attribuito all’arcipelago di “Patrimonio dell’Umanità”..

Nuove specie minerali al Somma-Vesuvio: fluoro-edenite

Despite the impossibility to make mineralogical researches on the field, the volcanic complex of Monte Somma-Vesuvius keeps surprising with new findings of mineral species for that locality. In an “old” sample belonging to Domenico Preite, picked up at Le Novelle quarry, Ercolano, Napoli, thanks to EDX and micro- FTIR analysis the fluoro-edenite was identified. This is the second Italian finding for the species after the one of the Etnean type locality of Monte Calvario, Biancavilla, Catania (Gianfagna & Oberti, 2001)

Critical renormalized coupling constants in the symmetric phase of the Ising models

Using a novel finite size scaling Monte Carlo method, we calculate the four, six and eight point renormalized coupling constants defined at zero momentum in the symmetric phase of the three dimensional Ising system. The results of the 2D Ising system that were directly measured are also reported. Our values of the six and eight point coupling constants are significantly different from those obtained from other methods.Comment: 7 pages, 2 figure

Two dimensional SU(N)xSU(N) Chiral Models on the Lattice (II): the Green's Function

Analytical and numerical methods are applied to principal chiral models on a two-dimensional lattice and their predictions are tested and compared. New techniques for the strong coupling expansion of SU(N) models are developed and applied to the evaluation of the two-point correlation function. The momentum-space lattice propagator is constructed with precision O(\beta^{10}) and an evaluation of the correlation length is obtained for several different definitions. Three-loop weak coupling contributions to the internal energy and to the lattice $\beta$ and $\gamma$ functions are evaluated for all N, and the effect of adopting the ``energy'' definition of temperature is computed with the same precision. Renormalization-group improved predictions for the two-point Green's function in the weak coupling ( continuum ) regime are obtained and successfully compared with Monte Carlo data. We find that strong coupling is predictive up to a point where asymptotic scaling in the energy scheme is observed. Continuum physics is insensitive to the effects of the large N phase transition occurring in the lattice model. Universality in N is already well established for $N \ge 10$ and the large N physics is well described by a ``hadronization'' picture.Comment: Revtex, 37 pages, 16 figures available on request by FAX or mai