Influence of a dynamical gluon mass in the pp and (p)over-bar-p forward scattering

We compute the tree level cross section for gluon-gluon elastic scattering taking into account a dynamical gluon mass, and show that this mass scale is a natural regulator for this subprocess cross section. Using an eikonal approach in order to examine the relationship between this gluon-gluon scattering and the elastic pp and (p) over barp channels, we found that the dynamical gluon mass is of the same order of magnitude as the ad hoc infrared mass scale m(0) underlying eikonalized QCD-inspired models. We argue that this correspondence is not an accidental result, and that this dynamical scale indeed represents the onset of nonperturbative contributions to the elastic hadron-hadron scattering. We apply the eikonal model with a dynamical infrared mass scale to obtain predictions for sigma(tot)(pp,(p) over barp), rho(pp,(p) over barp), slope B-pp,B-(p) over barp, and differential elastic scattering cross section d sigma((p) over barp)/dt at Tevatron and CERN-LHC energies.

Rho-omega mixing and the Nolen-Schiffer anomaly in relativistic nuclear models

We calculate within the framework of relativistic nuclear models the contribution of the ρ0 - ω mixing interaction to the binding energy differences of the mirror nuclei in the neighborhood of A = 16 and A = 40. We use two relativistic models for the nuclear structure, one with scalar and vector Woods-Saxon potentials, and the Walecka model. The ρ0 - ω interaction is treated in first order perturbation theory. When using the Walecka model the ρ- and ω-nucleon coupling constants are the same for calculating bound state wave functions and the perturbation due to the mixing. We find that the relativistic results on the average are of the same order as the ones obtained with nonrelativistic calculations.

A new limit of the AdS(5) x S-5 sigma model

Using the pure spinor formalism, a quantizable sigma model has been constructed for the superstring in an AdS(5) X S-5 background with manifest PSU(2,2 vertical bar 4) invariance. The PSU(2,2 vertical bar 4) metric g(AB) has both vector components gab and spinor components g, 3, and in the limit where the spinor components g, 3 are taken to infinity, the AdS5 X S5 sigma model reduces to the worldsheet action in a flat background. In this paper, we instead consider the limit where the vector components g(ab) are taken to infinity. In this limit, the AdS5 X S5 sigma model simplifies to a topological A-model constructed from fermionic N=2 superfields whose bosonic components transform like twistor variables. Just as d=3 Chern-Simons theory can be described by the open string sector of a topological A-model, the open string sector of this topological A-model describes d=4 N=4 super-Yang-Mills. These results might be useful for constructing a worldsheet proof of the Maldacena conjecture analogous to the Gopakumar-Vafa-Ooguri worldsheet proof of Chern-Simons/conifold duality.

Melatonin decreases breast cancer metastasis by modulating Rho-associated kinase protein-1 expression

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Perturbative super-Yang-Mills from the topological AdS 5 × S 5 sigma model

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Charge-symmetry breaking, rho-omega mixing, and the quark propagator

The momentum dependence of the ρ0-ω mixing contribution to charge-symmetry breaking (CSB) in the nucleon-nucleon interaction is compared in a variety of models. We focus in particular on the role that the structure of the quark propagator plays in the predicted behaviour of the ρ0-ω mixing amplitude. We present new results for a confining (entire) quark propagator and for typical propagators arising from explicit numerical solutions of quark Dyson-Schwinger equations We compare these to hadronic and free quark calculations The implications for our current understanding of CSB experiments is discussed.

In vitro production of bovine embryos using Sigma antioxidant supplement®, α-tocopherol and L-ascorbic acid

This study tested the effect of Sigma antioxidant supplement®, α-tocopherol (vitamin E) and L-ascorbic acid (vitamin C) in the culture medium of bovine embryos. In experiment 1, in vitro produced bovine zygotes were cultured in Human Tubal Fluid (HTF): Eagle’s Basic Medium (BME) with: Group 1 – 50 µm vitamin C; Group 2 – 200 µm vitamin E; Group 3 – 25 µm vitamin C and 100 µm vitamin E; Group 4 – 1 µl/ml Sigma antioxidant supplement®; and the Control group – HTF:BME only. In experiment 2, embryos were cultured in high or low oxygen tension with HTF:BME + Sigma antioxidant supplement® or in HTF:BME alone (Control). The data were analyzed using ANOVA followed by Tukey’s test. The results of experiment 1 showed a negative effect (P < 0.05) of vitamin E on blastocyst production in Group 2 (19.7 ± 0.1%). This effect was reduced in Group 3 by the addition of vitamin C (26.1 ± 0.2%). The use of vitamin C alone (34.9 ± 0.3%) or the Sigma antioxidant supplement® (33.3 ± 0.7%) did not increase (P > 0.05) the number of blastocysts produced compared with the control group (30.1 ± 0.5%). During experiment 2, there was no effect (P > 0.05) from the culture medium or the O2 concentrations used, indicating that the reduction of the O2 concentration did not improve blastocyst production.