Measurement of associated production of vector bosons and top quark-antiquark pairs in pp collisions at √s=7 TeV

The first measurement of vector-boson production associated with a top quark-antiquark pair in proton-proton collisions at √s=7 TeV is presented. The results are based on a data set corresponding to an integrated luminosity of 5.0 fb-1, recorded by the CMS detector at the LHC in 2011. The measurement is performed in two independent channels through a trilepton analysis of tt̄Z events and a same-sign dilepton analysis of tt̄V (V=W or Z) events. In the trilepton channel a direct measurement of the tt̄Z cross section σtt̄Z=0.28-0.11+0.14 (stat)-0.03+0.06 (syst) pb is obtained. In the dilepton channel a measurement of the tt̄V cross section yields σtt̄V=0.43-0.15+0.17 (stat)-0.07+0.09 (syst) pb. These measurements have a significance, respectively, of 3.3 and 3.0 standard deviations from the background hypotheses and are compatible, within uncertainties, with the corresponding next-to-leading order predictions of 0.137-0.016+0.012 and 0.306-0.053+0.031 pb. © 2013 CERN. Published by the American Physical Society.

Temario provisional anotado y organización del Vigesimoprimer Período de Sesiones = Annotated provisional agenda and organization of work of the Twenty-first Session = Ordre du jour provisoire annoté et organisation de la Vingt-et-unième Session

Incluye Bibliografía

El desarrollo de la producción y la utilización de la energía en América Latina: sus posibilidades y problemas: resumen del informe preliminar = A summary of the preliminary report on the development of energy production and utilization in Latin America: Possibilities and problems

Incluye Bibliografía

Desarrollo latinoamericano y la coyuntura económica internacional: Segunda evaluación regional de la Estrategia Internacional de Desarrollo, parte 1: desarrollo económico y social de América Latina = Latin American development and the inernational economic situation, part 1: economic and social development of Latin America

Incluye Bibliografía

El desarrollo social de América Latina en la postguerra = The social development of Latin America in the post-war period

Publicado sólo en español por Solar/Hachette de Buenos Aires