A possible explanation why the Theta+ is seen in some experiments and not in others

To understand the whole set of positive and null data on the Theta+(1530)-production, we suggest the hypothesis that multiquark hadrons are mainly generated from many-quark states, which emerge either as short-term hadron fluctuations, or as hadron remnants in hard processes. This approach allows us to describe both non-observation of the Theta+ in current null experiments and peculiar features of its production in positive experiments. Further, we are able to propose new experiments that might be decisive for the problem of the Theta+ existence. Distributions of the Theta+ in such experiments can give important information both on higher Fock components of conventional hadrons and about structure and hadronization properties of hadron remnants produced in hard processes. We also explain that description of multiquark hadrons may require a modified form of the constituent quark model, with quark masses and couplings being intermediate between their values for the familiar constituent quarks and the current ones.Comment: 18 pages. Some changes in the text; experimental suggestions collected in a special subsection, references added and refreshe

Resonances, and mechanisms of Theta-production

After explaining necessity of exotic hadrons, we discuss mechanisms which could determine production of the exotic Theta-baryon. A possible important role of resonances (producing the Theta in real or virtual decays) is emphasized for various processes. Several experimental directions for studies of such resonances, and the Theta itself, are suggested. We briefly discuss also recent negative results on the Theta-baryon.Comment: 6 page

NICMOS Snapshot Survey of Damped Lyman Alpha Quasars

We image 19 quasars with 22 damped Lyman alpha (DLA) systems using the F160W filter and the Near-Infrared Camera and Multiobject Spectrograph aboard the Hubble Space Telescope, in both direct and coronagraphic modes. We reach 5 sigma detection limits of ~H=22 in the majority of our images. We compare our observations to the observed Lyman-break population of high-redshift galaxies, as well as Bruzual & Charlot evolutionary models of present-day galaxies redshifted to the distances of the absorption systems. We predict H magnitudes for our DLAs, assuming they are producing stars like an L* Lyman-break galaxy (LBG) at their redshift. Comparing these predictions to our sensitivity, we find that we should be able to detect a galaxy around 0.5-1.0 L* (LBG) for most of our observations. We find only one new possible candidate, that near LBQS0010-0012. This scarcity of candidates leads us to the conclusion that most DLA systems are not drawn from a normal LBG luminosity function nor a local galaxy luminosity function placed at these high redshifts.Comment: 31 pages, 8 figures, Accepted for Feb. 10 issue of Ap

Physical activity, fitness and adiposity: immigrants versus spanish scholars (Actividad física, condición física y adiposidad: inmigrantes versus escolares españoles)

The objective was to analyse the associations of physical fitness and patterns of physical activity with adiposity in native and foreign. This study was performed with 612 school students (8-10 years). Anthropometric measurements, physical fitness and activity patterns were studied. The results showed that students who practiced more physical activity had lower body mass index and higher levels of fitness. Immigrants had lower adiposity and higher participation in sport activities than native students. No differences between native and foreing students in levels were found, except for immigrant girls, who showed greater lower body strengh than the natives ones. In conclusion, immigrants from this study appear to have a healthier fitness, physical activity and adiposity than natives. El objetivo fue analizar las asociaciones entre los niveles de condición física, patrones de actividad física y adiposidad del alumnado nativo e inmigrante. Se estudiaron 612 niños (8-10 años) de colegios públicos, valorándose mediante pruebas antropométricas, condición física y cuestionario de hábitos de actividad física. Se observó que el alumnado que realizaba mayor actividad física presentaba menor índice de masa corporal y mayor condición física. El alumnado inmigrante presentó menor adiposidad y mayor participación en actividades deportivas. No encontramos diferencias en condición física, salvo en chicas inmigrantes, con mayor fuerza del tren inferior. En conclusión, los inmigrantes del presente estudio parecen poseer un perfil más saludable de condición física, actividad física y adiposidad que los nativos

Pentaquark baryons in SU(3) quark model

We study the SU(3) group structure of pentaquark baryons which are made of four quarks and one antiquark. The pentaquark baryons form {1}, {8}, {10}, {10}-bar, {27}, and {35} multiplets in SU(3) quark model. First, the flavor wave functions of all the pentaquark baryons are constructed in SU(3) quark model and then the flavor SU(3) symmetry relations for the interactions of the pentaquarks with three-quark baryons and pentaquark baryons are obtained.Comment: REVTeX, 36 pages, 8 figures, references added, section for mass sum rules is added, to appear in Phys. Rev.

The ρ\rho Meson Light-Cone Distribution Amplitudes of Leading Twist Revisited

We give a complete re-analysis of the leading twist quark-antiquark light-cone distribution amplitudes of longitudinal and transverse $\rho$ mesons. We derive Wandzura-Wilczek type relations between different distributions and update the coefficients in their conformal expansion using QCD sum rules including next-to-leading order radiative corrections. We find that the distribution amplitudes of quarks inside longitudinally and transversely polarized $\rho$ mesons have a similar shape, which is in contradiction to previous analyses.Comment: 21 pages, latex2e, requires a4wide.sty and epsf.sty, 6 PS figures include

K*(892)0 Production in Relativistic Heavy Ion Collisions at sqrt(s_NN) = 130 GeV

Preliminary results on the K*(892)0 -> pi + K production using the mixed-event technique are presented. The measurements are performed at mid-rapidity by the STAR detector in sqrt(s_NN) = 130 GeV Au-Au collisions at RHIC. The K*0 to negative hadron, kaon and phi ratios are obtained and compared to the measurements in e+e-, pp and pbarp at various energies.Comment: 8 pages, 3 figures, proceedings of Strange Quarks in Matter (SQM2001), Frankfurt am Main, Germany, to be published in J. Phys.

On photoexcitation of baryon antidecuplet

We show that the photoexcitation of the baryon antidecuplet, suggested by the soliton classification of low-lying baryons, is strongly suppressed on the proton target. The process occurs mostly on the neutron target. This qualitative prediction can be useful in identifying the non-exotic members of the antidecuplet in the known baryon spectrum. We also analyze the interrelation between photocouplings of various baryon multiplets in the soliton picture and in the nonrelativistic quark model.Comment: 9 pages, one Latex figur

CLASH-VLT: The stellar mass function and stellar mass density profile of the z=0.44 cluster of galaxies MACS J1206.2-0847

Context. The study of the galaxy stellar mass function (SMF) in relation to the galaxy environment and the stellar mass density profile, rho(r), is a powerful tool to constrain models of galaxy evolution. Aims. We determine the SMF of the z=0.44 cluster of galaxies MACS J1206.2-0847 separately for passive and star-forming (SF) galaxies, in different regions of the cluster, from the center out to approximately 2 virial radii. We also determine rho(r) to compare it to the number density and total mass density profiles. Methods. We use the dataset from the CLASH-VLT survey. Stellar masses are obtained by SED fitting on 5-band photometric data obtained at the Subaru telescope. We identify 1363 cluster members down to a stellar mass of 10^9.5 Msolar. Results. The whole cluster SMF is well fitted by a double Schechter function. The SMFs of cluster SF and passive galaxies are statistically different. The SMF of the SF cluster galaxies does not depend on the environment. The SMF of the passive population has a significantly smaller slope (in absolute value) in the innermost (<0.50 Mpc), highest density cluster region, than in more external, lower density regions. The number ratio of giant/subgiant galaxies is maximum in this innermost region and minimum in the adjacent region, but then gently increases again toward the cluster outskirts. This is also reflected in a decreasing radial trend of the average stellar mass per cluster galaxy. On the other hand, the stellar mass fraction, i.e., the ratio of stellar to total cluster mass, does not show any significant radial trend. Conclusions. Our results appear consistent with a scenario in which SF galaxies evolve into passive galaxies due to density-dependent environmental processes, and eventually get destroyed very near the cluster center to become part of a diffuse intracluster medium.Comment: A&A accepted, 15 pages, 13 figure

On asymmetry in inclusive pion production

On the basis of the mechanism proposed for one-spin asymmetries in inclusive hadron production we specify an $x$--dependence of asymmetries in inclusive processes of pion production. The main role in generation of this asymmetry belongs to the orbital angular momentum ofquark-antiquark cloud in internal structure of constituent quarks. The $x$--dependence of asymmetries in the charged pion production at large $x$ reflects the corresponding dependence of constituent quark polarization in the polarized proton.Comment: LaTeX, 8 pages, 3 figures. One figure added, as it appears in Phys. Rev.