26,060 research outputs found
Tetraquark Production in Double Parton Scattering
We develop a model to study tetraquark production in hadronic collisions. We
focus on double parton scattering and formulate a version of the color
evaporation model for the production of the and of the
tetraquark, a state composed by the quarks. We find that
the production cross section grows rapidly with the collision energy
and make predictions for the forthcoming higher energy data of the LHC.Comment: 13 pages, 3 figures. Corrections in the text and reference
Testing Intra-Industry Trade Between Portugal and Spain [1990-1996]
This paper shows how, in the period 1990-1996, economic integration between the two Iberian economies has deepened through intra-industry trade. The enquiry was led at the level of the main forty traded products. In this context, several tests have been made. Our analysis combines first the application of the Grubel and Lloyd index of the main forty products and the marginal intra-industry trade of Brulhart, and Brulhart and Elliot. On the basis of these indexes we defined our criterion for the selection of the competitive cluster of Portugal throughout the period. We have also considered the global intra-industry trade, in nominal and real terms, according to the method of Greenaway et al. In econometric terms we have tried to know which is the relation between the intra-industry trade index and the marginal intra-industry trade at the level of the main forty products, the results however were not unequivocal. The same is true as far as concerns the relation between the intra-industry trade index and the net export position at the level of the same products. Despite the fact that some attempts have been inconclusive, knowledge about Iberian trade has developed in a field essential to its upgrading, and the way is open for further research.intra-industry trade; marginal intra-industry trade; competitive cluster; net export position.
Morphology of low-redshift compact galaxy clusters I. Shapes and radial profiles
The morphology of clusters of galaxies may be described with a set of
parameters which contain information about the formation and evolutionary
history of these systems. In this paper we present a preliminary study of the
morphological parameters of a sample of 28 compact Abell clusters extracted
from DPOSS data. The morphology of galaxy clusters is parameterized by their
apparent ellipticity, position angle of the major axis, centre coordinates,
core radius and beta-model power law index. Our procedure provides estimates of
these parameters by simultaneously fitting them all, overcoming some of the
difficulties induced by sparse data and low number statistics typical of this
kind of analysis. The cluster parameters were fitted in a 3 x 3 h^-2 sqMpc
region, measuring the background in a 2 <R< 2.5 h^-1Mpc annulus. We also
explore the correlations between shape and profile parameters and other cluster
properties. One third of this compact cluster sample has core radii smaller
than 50 h^-1 kpc, i.e. near the limit that our data allow us to resolve,
possibly consistent with cusped models. The remaining clusters span a broad
range of core radii up to 750 h^-1 kpc. More than 80 per cent of this sample
has ellipticity higher than 0.2. The alignment between the cluster and the
major axis of the dominant galaxy is confirmed, while no correlation is
observed with other bright cluster members. No significant correlation is found
between cluster richness and ellipticity. Instead, cluster richness is found to
correlate, albeit with large scatter, with the cluster core radius.[abridged]Comment: 23 pages, 17 figures, accepted for publication in MNRAS. Full paper
including full resolution figures 2 and 9 at
http://www.eso.org/~vstrazzu/P/ME1030fv.pd
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