Aachen 2019 – scientific programme

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T: Fachverband Teilchenphysik

T 14: Elektroschwache Wechselwirkung

T 14.4: Talk

Monday, March 25, 2019, 16:50–17:05, S14

Observations of massive gauge boson scattering in the like-charged WWjj final state and the WZjj final state with the ATLAS detector at the LHC — •Tim Herrmann, Carsten Bittrich, Stefanie Todt, Franziska Iltzsche, Abhishek Nag, Joany Manjarres, and Michael Kobel — TU Dresden, Germany

Scattering of massive gauge bosons (VBS) is predicted by the Standard Model but was not observed by independent experiments before. There are new observations from the ATLAS experiment at LHC of VBS in the WZjj (5.35 σ) and WWjj (6.9 σ) same sign final state. It is the first observation of VBS in the WZjj final state.

VBS gives insights into and probes the electroweak symmetry breaking of the SM. It is sensitive to quartic and triple gauge couplings and s- and t-channel gauge boson exchanges. The measured differential cross sections are sensitive to the strengths of these contributions.

Data taken in 2015 and 2016 at a center of mass energy of (s)^1/ = 13 TeV at the ATLAS detector at the LHC with a total luminosity of 36.1 fb⁻¹ are analyzed.

For the WZjj final state multivariate methods (BDT) together with a template fit to the BDT shape are used to separate signal from backgrounds and to determine the significance.

The WWjj same sign final state has the best signal to background ratio. A cut-based selection involving data driven background estimation methods for non-prompt leptons and charge flips is applied to establish the signal. The significance is determined with a template fit involving seven control regions and 25 bins in the signal region.