Three-quark potentials in an SU(3)SU(3) effective Polyakov loop model

Three-quark potentials are studied in great details in the three-dimensional $SU(3)$ pure gauge theory at finite temperature, for the cases of static sources in the fundamental and adjoint representations. For this purpose, the corresponding Polyakov loop model in its simplest version is adopted. The potentials in question, as well as the conventional quark--anti-quark potentials, are calculated numerically both in the confinement and deconfinement phases. Results are compared to available analytical predictions at strong coupling and in the limit of large number of colors $N$. The three-quark potential is tested against the expected $\Delta$ and $Y$ laws and the $3q$ string tension entering these laws is compared to the conventional $q\bar{q}$ string tension. As a byproduct of this investigation, essential features of the critical behaviour across the deconfinement transition are elucidated.Comment: 28 pages, 18 figures, 4 tables; some text and a few references added; version accepted for publication on Nucl. Phys.

The Wishart short rate model

We consider a short rate model, driven by a stochastic process on the cone of positive semidefinite matrices. We derive sufficient conditions ensuring that the model replicates normal, inverse or humped yield curves

TMD PDF's: gauge invariance, RG properties and Wilson lines

The UV divergences associated with transverse-momentum dependent (TMD) parton distribution functions (PDF) are calculated together with the ensuing one-loop anomalous dimensions in the light-cone gauge. Time-reversal-odd effects in the anomalous dimensions are observed and the role of Glauber gluons is discussed. A generalized renormalization procedure of TMD PDFs is proposed, relying upon the renormalization of contour-dependent operators with obstructions.Comment: 4 pages, 1 figure. Talk presented at the International Workshop on Diffraction in High Energy and Nuclear Physics, La Londe-les-Maures, France, 9-14 Sept 2008. v2: 5 pages, preprint number and e-mail addresses adde

Features of elastic scattering at small t at the LHC

The problems linked with the extraction of the basic parameters of the hadron elastic scattering amplitude at the LHC are explored. It is shown that one should take into account the saturation regime which will lead to new effects at the LHC.Comment: 3. pages, 6 figures, talk on the International workshop on "Diffraction in High Energy Physics", La Londe-les-Maures, France (2008

Chandra studies of the globular cluster 47 Tucanae: A deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars, and new constraints to r-mode instability window

We combined Chandra ACIS observations of the globular cluster 47 Tucanae (hereafter, 47 Tuc) from 2000, 2002, and 2014-15 to create a deeper X-ray source list, and study some of the faint radio millisecond pulsars (MSPs) present in this cluster. We have detected 370 X-ray sources within the half-mass radius (2$'$.79) of the cluster, 81 of which are newly identified, by including new data and using improved source detection techniques. The majority of the newly identified sources are in the crowded core region, indicating cluster membership. We associate five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al. (2001). We present alternative positions derived from two methods, centroiding and image reconstruction, for faint, crowded sources. We are able to extract X-ray spectra of the recently discovered MSPs 47 Tuc aa, 47 Tuc ab, the newly timed MSP 47 Tuc Z, and the newly resolved MSPs 47 Tuc S and 47 Tuc F. Generally, they are well fit by black body or neutron star atmosphere models, with temperatures, luminosities and emitting radii similar to those of other known MSPs in 47 Tuc, though 47 Tuc aa and 47 Tuc ab reach lower X-ray luminosities. We limit X-ray emission from the full surface of the rapidly spinning (542 Hz) MSP 47 Tuc aa, and use this limit to put an upper bound for amplitude of r-mode oscillations in this pulsar as $\alpha<2.5\times 10^{-9}$ and constrain the shape of the r-mode instability window.Comment: 17 pages, 11 figures, 6 tables, Accepted for publication in MNRA

Tpz1TPP1 SUMOylation reveals evolutionary conservation of SUMO-dependent Stn1 telomere association

Elongation of the telomeric overhang by telomerase is counteracted by synthesis of the complementary strand by the CST complex, CTC1(Cdc13)/Stn1/Ten1. Interaction of budding yeast Stn1 with overhang-binding Cdc13 is increased by Cdc13 SUMOylation. Human and fission yeast CST instead interact with overhang-binding TPP1/POT1. We show that the fission yeast TPP1 ortholog, Tpz1, is SUMOylated. Tpz1 SUMOylation restricts telomere elongation and promotes Stn1/Ten1 telomere association,and a SUMO-Tpz1 fusion protein has increased affinity for Stn1. Our data suggest that SUMO inhibits telomerase through stimulation of Stn1/Ten1 action by Tpz1, highlighting the evolutionary conservation of the regulation of CST function by SUMOylation

Massive Stars in the Range 13−25M⊙\rm 13-25 M_\odot: Evolution and Nucleosynthesis. II. the Solar Metallicity Models

We present the evolutionary properties of a set of massive stellar models (namely 13, 15, 20 and 25 $\rm M_\odot$) from the main sequence phase up to the onset of the iron core collapse. All these models have initial solar chemical composition, i.e. Y=0.285 and Z=0.02. A 179 isotope network, extending from neutron up to $\rm ^{68}Zn$ and fully coupled to the evolutionary code has been adopted from the Carbon burning onward. Our results are compared, whenever possible, to similar computations available in literature.Comment: 42 pages, 18 figures, 26 tables, accepted for publicatin in ApJ

Urban strategies for the future development of Turin and Skopje: economic crisis and effectiveness of urban design

This paper focuses on the issues of effectiveness of the urban plans in the context of the contemporary European cities, considering mainly the subject of physical transformation of public space connected with building development. The comparison between Turin and Skopje aims to highlight the possible role of the urban design tools and planning (especially diachronic visioning), in the future of a sustainable growth of the urban European systems. The strategies of visioning of the urban plans require, to become effective, a strong liability coming from the political power and the economic feasibility: how can we consider the production of plans when this liability is going to lack? The crisis of the building sector in recent years along Europe has underlined some weaknesses of this approach to plans which had been a good instrument in a perspective of economic and physical growth. This paper assumes that the urban plan will continue to be a fundamental instrument for managing the future transformations of our cities, if we will be capable of rethinking it as a device for reassembling and including many other implications, beyond those which are usually considered by drawing the material shape of things. The paper will finally attempt to describe some strategies for rethinking the urban plan visioning from a methodological point of view

Self similar Barkhausen noise in magnetic domain wall motion

A model for domain wall motion in ferromagnets is analyzed. Long-range magnetic dipolar interactions are shown to give rise to self-similar dynamics when the external magnetic field is increased adiabatically. The power spectrum of the resultant Barkhausen noise is of the form $1/\omega^\alpha$, where $\alpha\approx 1.5$ can be estimated from the critical exponents for interface depinning in random media.Comment: 7 pages, RevTex. To appear in Phys. Rev. Let