2017 Theses Doctoral

A search for new diboson resonances in the boosted semi-leptonic final state at √s = 13 TeV with the ATLAS detector

Carbone, Ryne Michael

A search is presented for new resonances decaying to a pair of boosted Standard Model bosons, WV, where the W boson decays leptonically (W → lν, with l = e, µ) and the other weak boson, V (V=W,Z), decays hadronically (V → qq¯
0/qq¯, with q, q0 = u, d, c, s, b). The data were collected with the ATLAS detector at the CERN Large Hadron Collider, during the 2015 and 2016 periods of pp collisions, at a center-of-mass energy √s = 13 TeV, and correspond to a total integrated luminosity of 36.1 fb^−1.
The hadronic decay of the boosted $V$ boson is reconstructed as a single large-radius jet, and the leptonic decay of the W boson is reconstructed as a lepton and missing transverse energy. The search is sensitive to resonances produced with quark-antiquark fusion, gluon-gluon fusion, and vector-boson fusion. No significant excesses are observed above the Standard Model background prediction. Upper limits on production cross section times branching ratio to WV are set at a 95 % confidence level for selected benchmark signal models. Models of a neutral, narrow scalar boson (spin-0), charged and neutral vector bosons (spin-1) coupling to the Standard Model gauge bosons, and a neutral Randall-Sundrum bulk graviton (spin-2) are considered. The search significantly improves the limits produced in recent searches.