Production of exotic charmonium in γγ\gamma \gamma interactions at hadronic colliders

In this paper we investigate the Exotic Charmonium (EC) production in $\gamma \gamma$ interactions present in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC) energies as well as for the proposed energies of the Future Circular Collider (FCC). Our results demonstrate that the experimental study of these processes is feasible and can be used to constrain the theoretical decay widths and shed some light on the configuration of the considered multiquark states.Comment: 7 pages, 2 figures, 3 tables. v2: Revised version published in Physical Review

Collaboration networks from a large CV database: dynamics, topology and bonus impact

Understanding the dynamics of research production and collaboration may reveal better strategies for scientific careers, academic institutions and funding agencies. Here we propose the use of a large and multidisciplinar database of scientific curricula in Brazil, namely, the Lattes Platform, to study patterns of scientific production and collaboration. In this database, detailed information about publications and researchers are made available by themselves so that coauthorship is unambiguous and individuals can be evaluated by scientific productivity, geographical location and field of expertise. Our results show that the collaboration network is growing exponentially for the last three decades, with a distribution of number of collaborators per researcher that approaches a power-law as the network gets older. Moreover, both the distributions of number of collaborators and production per researcher obey power-law behaviors, regardless of the geographical location or field, suggesting that the same universal mechanism might be responsible for network growth and productivity.We also show that the collaboration network under investigation displays a typical assortative mixing behavior, where teeming researchers (i.e., with high degree) tend to collaborate with others alike. Finally, our analysis reveals that the distinctive collaboration profile of researchers awarded with governmental scholarships suggests a strong bonus impact on their productivity.Comment: 8 pages, 8 figure

Thermodynamic potential with correct asymptotics for PNJL model

An attempt is made to resolve certain incongruities within the Nambu - Jona-Lasinio (NJL) and Polyakov loop extended NJL models (PNJL) which currently are used to extract the thermodynamic characteristics of the quark-gluon system. It is argued that the most attractive resolution of these incongruities is the possibility to obtain the thermodynamic potential directly from the corresponding extremum conditions (gap equations) by integrating them, an integration constant being fixed in accordance with the Stefan-Boltzmann law. The advantage of the approach is that the regulator is kept finite both in divergent and finite valued integrals at finite temperature and chemical potential. The Pauli-Villars regularization is used, although a standard 3D sharp cutoff can be applied as well.Comment: 16 pages, 5 figures, extended version, title change

Chemical control of stem-end rot on mango fruits in the San Francisco river Valley.

The objective of this study was to assess the efficacy of some fungicides in reducing the incidence of stem-end rot when applied after flowering onset

Vacuum polarization on the spinning circle

Vacuum polarization of a massive scalar field in the background of a two-dimensional version of a spinning cosmic string is investigated. It is shown that when the `radius of the universe' is such that spacetime is globally hyperbolic the vacuum fluctuations are well behaved, diverging though on the `chronology horizon'. Naive use of the formulae when spacetime is nonglobally hyperbolic leads to unphysical results. It is also pointed out that the set of normal modes used previously in the literature to address the problem gives rise to two-point functions which do not have a Hadamard form, and therefore are not physically acceptable. Such normal modes correspond to a locally (but not globally) Minkowski time, which appears to be at first sight a natural choice of time to implement quantization.Comment: 3 pages, no figures, REVTeX4, published versio

Spin-phonon coupling in multiferroic RCrO3_3 (R-Y, Lu, Gd, Eu, Sm): A Raman study

Raman study on a select few orthochromites, RCrO$_3$ (R = Y, Lu, Gd, Eu and Sm) shows that the phonon behavior at TN in compounds with magnetic R-ion (Gd and Sm) is remarkably different from that of non-magnetic R-ion (Y, Lu and Eu). While anomalies in most of the observed phonon frequencies in all these compounds may result from the distortion of CrO$_6$ octahedra due to size effect and magnetostriction arising from Cr-ordering, the anomalous behavior of their linewidths observed at TN for the compounds with only magnetic R-ion suggests spin-phonon coupling. The presence of spin-phonon coupling and the anomalies in the low frequency modes related to R-ion motion in orthochromites (R = Gd and Sm) support the suggestion that the coupling between 4f-3d moments play important role in inducing switchable electric polarization.Comment: 6 pages (two column format), 7 figures; The updated version of the manuscript can be found at Euro. Phys. Lett. 101, 17008 (2013

Note on the point-splitting procedure to evaluate vacuum fluctuation in certain cylindrically symmetric backgrounds

We revisit two-point function approaches used to study vacuum fluctuation in wedge-shaped regions and conical backgrounds. Appearance of divergent integrals is discussed and circumvented. The issue is considered in the context of a massless scalar field in cosmic string spacetime.Comment: REVTeX file, 7 page

Variabilidade genética de isolados de Armillaria sp. da região sul do Brasil.

Resumo

Aplicação de abamectina como alternativa de controle químico do nematoide-das-galhas em melão.

O objetivo do trabalho foi avaliar o efeito da abamectina na redução populacional de M. incognita, na cultura do melão