[Seminars] HEP Seminar TODAY

[Holly Hernandez]

HIGH ENERGY PHYSICS SEMINAR TODAY

Monday January 5, 2015
LASR 162
4:15pm

Speaker: Ho Ling Li (UChicago)

Title: Search for W’ —> tb in the hadronic final state at ATLAS

Abstract: Before 2014, the search for a massive W' gauge boson in the decay channel of tb was only carried out with top decaying leptonically into lνb. This talk presents the first result on W' -> tb with top decaying hadronically into qqb, performed with data corresponding to 20.3/fb of integrated luminosity collected by the ATLAS detector at the LHC in pp collisions at a center-of-mass energy of sqrt(s) = 8 TeV. This analysis searches for W' with masses above 1.5 TeV, where the W' decay products have large momentum. Novel jet substructure techniques are used to identify jets from high momentum top quarks to ensure high sensitivity, independent of W' mass, up to 3 TeV; b-tagging is also used to identify jets originating from bottom quarks. The data is consistent with the Standard Model background-only expectations, and 95% Confidence Level limits are set on the W' -> tb cross section times branching ratio ranging from 0.16 pb to 0.33 pb for left-handed W' bosons, and ranging from 0.10 pb to 0.21 pb for right-handed W'. In addition, 95% Confidence Level limits are set on the W'-boson coupling to tb as a function of the W' mass using a model independent effective field theory approach. The outlook of this search will also be discussed.