Logarithmic Clustering in Submonolayer Epitaxial Growth

We investigate submonolayer epitaxial growth with a fixed monomer flux and irreversible aggregation of adatom islands due to their effective diffusion. When the diffusivity D_k of an island of mass k is proportional to k^{-\mu}, a Smoluchowski rate equation approach predicts steady behavior for 0<\mu<1, with the concentration c_k of islands of mass k varying as k^{-(3-\mu)/2}. For \mu>1, continuous evolution occurs in which c_k(t)~(\ln t)^{-(2k-1)\mu/2}, while the total island density increases as N(t)~(\ln t)^{\mu/2}. Monte Carlo simulations support these predictions.Comment: 4 pages, 2 figure

GHASP: an H{\alpha} kinematic survey of spiral and irregular galaxies -- IX. The NIR, stellar and baryonic Tully-Fisher relations

We studied, for the first time, the near infrared, stellar and baryonic Tully-Fisher relations for a sample of field galaxies taken from an homogeneous Fabry-Perot sample of galaxies (the GHASP survey). The main advantage of GHASP over other samples is that maximum rotational velocities were estimated from 2D velocity fields, avoiding assumptions about the inclination and position angle of the galaxies. By combining these data with 2MASS photometry, optical colors, HI masses and different mass-to-light ratio estimators, we found a slope of 4.48\pm0.38 and 3.64\pm0.28 for the stellar and baryonic Tully-Fisher relation, respectively. We found that these values do not change significantly when different mass-to-light ratios recipes were used. We also point out, for the first time, that rising rotation curves as well as asymmetric rotation curves show a larger dispersion in the Tully-Fisher relation than flat ones or than symmetric ones. Using the baryonic mass and the optical radius of galaxies, we found that the surface baryonic mass density is almost constant for all the galaxies of this sample. In this study we also emphasize the presence of a break in the NIR Tully-Fisher relation at M(H,K)\sim-20 and we confirm that late-type galaxies present higher total-to-baryonic mass ratios than early-type spirals, suggesting that supernova feedback is actually an important issue in late-type spirals. Due to the well defined sample selection criteria and the homogeneity of the data analysis, the Tully-Fisher relation for GHASP galaxies can be used as a reference for the study of this relation in other environments and at higher redshifts.Comment: 16 pages, 6 figures. Accepted for publication in MNRA

Dirac quantization of a nonminimal gauged O(3) sigma model

The (2+1) dimensional gauged O(3) nonlinear sigma model with Chern-Simons term is canonically quantized. Furthermore, we study a nonminimal coupling in this model implemented by means of a Pauli-type term. It is shown that the set of constraints of the model is modified by the introduction of the Pauli coupling. Moreover, we found that the quantum commutator relations in the nominimal case is independent of the Chern-Simons coefficient, in contrast to the minimal one.Comment: 7 pages, to appear in Modern Physics Letters

A low-energy effective Yang-Mills theory for quark and gluon confinement

We derive a gauge-invariant low-energy effective model of the Yang-Mills theory. We find that the effective gluon propagator belongs to the Gribov-Stingl type and agrees with it when a mass term which breaks nilpotency of the BRST symmetry is included. We show that the effective model with gluon propagator of the Gribov-Stingl type exhibits both quark and gluon confinement: the Wilson loop average has the area law and the Schwinger function violates reflection positivity. However, we argue that both quark and gluon confinement can be obtained even in the absence of such a mass term.Comment: 5 pages, no figures; accepted for publication in Physical Review D (Rapid Communication

The Contribution of the Smectic-Nematic Interface to the Surface Energy

The contribution of the smectic-nematic interface to the surface energy of a nematic liquid crystal sample is analyzed. By means of a simple model it is shown that the surface energy depends on the thickness of the region over which the transition smectic-nematic takes place. For perfectly flat substrates this thickness is of the order of the correlation length entering in the transition. An estimate of this contribution shows that it is greater than the one arising from the nematic-substrate interaction. Moreover, it is also shown that the surface energy determined in this way presents a non-monotonic behavior with the temperature.Comment: 10 pages, revte

Transition from small to large world in growing networks

We examine the global organization of growing networks in which a new vertex is attached to already existing ones with a probability depending on their age. We find that the network is infinite- or finite-dimensional depending on whether the attachment probability decays slower or faster than $(age)^{-1}$. The network becomes one-dimensional when the attachment probability decays faster than $(age)^{-2}$. We describe structural characteristics of these phases and transitions between them.Comment: 5 page

Dynamical effects of interactions and the Tully-Fisher relation for Hickson compact groups

We investigate the properties of the B-band Tully-Fisher (T-F) relation for 25 compact group galaxies, using Vmax derived from 2-D velocity maps. Our main result is that the majority of the Hickson Compact Group galaxies lie on the T-F relation. However, about 20% of the galaxies, including the lowest-mass systems, have higher B luminosities for a given mass, or alternatively, a mass which is too low for their luminosities. We favour a scenario in which outliers have been brightened due to either enhanced star formation or merging. Alternatively, the T-F outliers may have undergone truncation of their dark halo due to interactions. It is possible that in some cases, both effects contribute. The fact that the B-band T-F relation is similar for compact group and field galaxies tells us that these galaxies show common mass-to-size relations and that the halos of compact group galaxies have not been significantly stripped inside R25. We find that 75% of the compact group galaxies studied (22 out of 29) have highly peculiar velocity fields. Nevertheless, a careful choice of inclination, position angle and center, obtained from the velocity field, and an average of the velocities over a large sector of the galaxy enabled the determination of fairly well-behaved rotation curves for the galaxies. However, two of the compact group galaxies which are the most massive members in M51--like pairs, HCG 91a and HCG 96a, have very asymmetric rotation curves, with one arm rising and the other one falling, indicating, most probably, a recent perturbation by the small close companions.Comment: 15 pages, 4 figures, accepted for publication in the Astronomical Journa