Studying the Wtb vertex structure using recent LHC results

The Wtb vertex structure and the search for new anomalous couplings is studied using top quark measurements obtained at the LHC, for a center-of-mass energy of 8 TeV. By combining the latest and most precise results on the single top quark production cross section and the measurements of the W-boson helicity fractions (F0 and FL), it is possible to set new limits, at a 95% C.L., on the real and imaginary components of the new couplings. The combination of the LHC observables clearly improves the limits obtained when using the individual results alone. The updated measurements of the W-boson helicity fractions and the s+t channels’ electroweak single top quark production, at the Tevatron, improve the LHC limits when a world combination of all observables (LHC+Tevatron) is performed.

This work was partially supported by Fundacao para a Ciencia e Tecnologia, FCT (Project No. CERN/FP/123619/2011, Grant No. SFRH/BI/52524/2014 and Contract No. IF/00050/2013). The work of M. C. N. Fiolhais was supported by LIP-Laboratorio de Instrumentacao e Fisica Experimental de Particulas, Portugal (Grant No. PestIC/FIS/LA007/2013). The authors would like to thank the support of CRUP (Conselho de Reitores das Universidades Portuguesas) through Accao integrada Ref. E 2/09 and the MAP-Fis Program (the Joint Doctoral Programs of the Universities of Minho, Aveiro and Porto, http://www.map.edu.pt/fis/home). Special thanks go to Juan Antonio Aguilar-Saavedra for all the fruitful discussions and a long-term collaboration.