A comparative study of two 47 Tuc giant stars with different s-process enrichment

Here we aim to understand the origin of 47 Tuc's La-rich star Lee 4710. We report abundances for O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Co, Ni, Zn, Y, Zr, Ba, La, Ce, Pr, Nd, and Eu, and present a detailed abundance analysis of two 47 Tuc stars with similar stellar parameters but different slow neutron-capture (s-)process enrichment. Star Lee 4710 has the highest known La abundance ratio in this cluster ([La/Fe] = 1.14), and star Lee 4626 is known to have normal s-process abundances (e.g., [Ba/Eu]$<0$). The nucleosynthetic pattern of elements with Z$\gtrsim$56 for star Lee 4710 agrees with the predicted yields of a $1.3M_{\odot}$ asymptotic giant branch (AGB) star. Therefore, Lee 4710 may have been enriched by mass transfer from a more massive AGB companion, which is compatible with its location far away from the center of this relatively metal-rich ([Fe/H]$\sim-0.7$) globular cluster. A further analysis comparing the abundance pattern of Lee 4710 with data available in the literature reveals that nine out of the $\sim200$ 47 Tuc stars previously studied show strong s-process enhancements that point towards later enrichment by more massive AGB stars.Comment: ApJL in press. 6 pages, 4 figure

Effects of an extra Z′Z' gauge boson on the top quark decay t−−>cγt --> c \gamma

The effects of an extra $Z'$ gauge boson with family nonuniversal fermion couplings on the rare top quark decay $t --> c$gamma$are first examined in a model independent way and then in the minimal 331 model. It is found that the respective branching fraction is at most of the order of$10^{-8}$for$m_{Z'}=500$GeV and dramatically decreases for a heavier$Z'$boson. This results is in sharp contrast with a previous evaluation of this decay in the context of topcolor assisted technicolor models, which found that$B(t --> c \gamma)\sim 10^{-6}$for$m_{Z'}=1$ TeV.Comment: New paragraphs included to clarify our results, conclusion remains unchange

Inference of mixed information in Formal Concept Analysis

Negative information can be considered twofold: by means of a negation operator or by capturing the absence of information. In this second approach, a new framework have to be developed: from the syntax to the semantics, including the management of such generalized knowledge representation. In this work we traverse all these issues in the framework of formal concept analysis, introducing a new set of inference rules to manage mixed (positive and negative) attributes.TIN2014-59471-P of the Science and Innovation Ministry of Spain, co-funded by the European Regional Development Fund (ERDF). UNIVERSIDAD DE MÁLAGA. Campus de Excelencia Internacional Andalucía Tech